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Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 71
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 72
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 73
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 74
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 75
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 76
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 77
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 78
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 79
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 80
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 81
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 82
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 83
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 84
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 85
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 86
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 87
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 88
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 89
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 90
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 91
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 92
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 93
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 94
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 95
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 96
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 97
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 98
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 99
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 100
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 101
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 102
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 103
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 104
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 105
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 106
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 107
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 108
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 109
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 110
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 111
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 112
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 113
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 114
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 115
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 116
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 117
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 118
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 119
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 120
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 121
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 122
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 123
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 124
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 125
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 126
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 127
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 128
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 129
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 130
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 131
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 132
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 133
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 134
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 135
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 136
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 137
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 138
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 139
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 140
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 141
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 142
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 143
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 144
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 145
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 146
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 147
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 148
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 149
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 150
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 151
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 152
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 153
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 154
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 155
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 156
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 157
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 158
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 159
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 160
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 161
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 162
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 163
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 164
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 165
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 166
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 167
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 168
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 169
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 170
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 171
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 172
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 173
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 174
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 175
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 176
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 177
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 178
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 179
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 180
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 181
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 182
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 183
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Page 184
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 185
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 186
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
×
Page 187
Suggested Citation:"Recovery of Motor Function." National Research Council. 1957. Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries. Washington, DC: The National Academies Press. doi: 10.17226/18485.
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Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Chapter HI RECOVERY OF MOTOR FUNCTION Melvin D. Yahr and Gilbert W. Beebe A. INTRODUCTION Of all the functions subserved by the peripheral nerves, that of movement is perhaps the most strategic to adequate performance by the affected limb, and is certainly the most susceptible of reliable assessment. Although practical function involves a great deal more than the strength of discrete movements, the latter provide an excellent approach to the investigation of the basic sources of variation in the regeneration of peripheral nerves. Only from such knowledge can the surgeon hope to plan effectively for the care of the individual patient with an injury to a peripheral nerve, whether it be an injury of war or the result of an ordinary accident. The surgeon needs to know what results to expect from his efforts at repair, and from his decisions not to resect and suture, and to know this not only in terms of the probability that a particular result will fall at one point or another on some scale of relative excellence but also in terms of those characteristics of injury and alternatives in management which tend to determine end result. Strength of movement constitutes a valuable statistical device for describing variation and for ferreting out factors which play a significant part in it, and it is appropriate, therefore, that the motor chapter contain a systematic study of the factors associated with variation in regeneration. There are, of course, other interests in regeneration but in the main these require more specialized study than seems feasible on the basis of the clinical records of military hospitals and the follow-up studies provided by a large cooperative investigation. The theoretical basis for understanding peripheral nerve regeneration is naturally of great concern to the surgeon, but it is too much to expect that his clinical observations on regeneration will contribute more than indirectly to the advancement of such theoretical knowledge. In the plan of the chapter there is first a methodological part in which are described the various methods used in the assessment of motor regenera- tion. There follows an essentially descriptive treatment of the statistical data on motor recovery in representative samples of peripheral nerve injuries treated by suture or by lysis. The two remaining parts of the chapter are rather more analytical in nature, being directed at some of the factors which have been thought to influence regeneration, factors which 71

are of such nature as to be identifiable in clinical material, e. g., length of surgical gap, and type of suture material. Since adequate reinnervation is but one determinant of satisfactory muscular movement, complete absence of movement is compatible with alternative explanations of very different implications for regeneration. Parallel electrical studies are of value in determining when absence of movement probably connotes failure of regeneration and when other factors are involved. Electrical data constitute the subject of a subsequent chapter which includes an analysis of the relation between voluntary movement and that induced by electrical stimulation. B. METHODS OF EVALUATING MOTOR FUNCTION Most of the skilled acts which are affected by peripheral nerve injury depend upon the coordinated movement of sets of muscles innervated by more than one peripheral nerve. In order to assess the regeneration of a particular peripheral nerve it is imperative that the examiner isolate the movements of those muscles which were affected by the injury. The basic motor examination, in turn, consists of evaluating the movements of such individual muscles as act alone, or of groups of cooperating muscles innervated by a single nerve. In the analysis of such motor function one may pass in review the ratings on each muscle or seek some method of combining the information about the entire set of affected muscles. Al- though both methods have been followed in the present study, chief atten- tion has been accorded to the individual muscle; methods of describing the set of affected muscles, e. g., by averaging, have seemed essentially arbitrary in principle and without any real advantage except the convenience of a smaller bulk of data. Examiners differ as to their willingness to infer the power of a specific muscle from the strength of a certain movement, and the choice of muscles for routine testing in the present study represents some compromise among the responsible investigators. An initial list of movements was agreed upon at the Hot Springs meeting discussed earlier, but as the examination forms and coding sheets were developed a number of changes seemed necessary and the final list appears in table 48. The abductor pollicis brevis was not originally accepted as a standard muscle for purposes of testing, but in two centers this muscle was routinely examined and it appears in the final analysis of individual muscles. The muscles marked for intensive study represent a further selection on the basis of representativeness, ease of examination, and accuracy of assessment. At the time of the Hot Springs meeting it was proposed that the observa- tions on each muscle extend to a tracing of the motion as a curve in space as well as to the measurement of its strength. Each aspect of the motion would then be expressed quantitatively, as a fraction of the normal, and the product of these two fractions would be taken as the final measure of performance for the individual muscle. In the end, however, agreement was reached on a much simpler plan in which attention was confined to n

Table 48.—Standard Muscles Chosen JOT Routine Follow-up Study, by Nerve and by Proximal or Distal Location Nerve Muscle Proximal Distal Median Flexor Carpi Radial is Flexor Pollicis Longus.1 Flexor Digitorum Profundus 2.' Abductor Pollicis Brevis.1 Ulnar Flexor Carpi Ulnaris. Abductor Digiti Quinti 1 Flexor Digitorum Profundus 4 and 5.' Adductor Pollicis. 1st Dorsal Interosseus.1 Radial Triceps. Bracbioradialis. Extensor Carpi Radialis.1 Extensor Digitorum Communis.1 Extensor Carpi Ulnaris. Extensor Pollicis Longus.1 Extensor Pollicis Brevis. Tibial and Sciatic- Gastrocnemius-Soleus.1 Tibialis Posticus. Flexor Digitorum Longus.1 Flexor Hallucis Longus.1 Interossei (any intrinsic muscle). tibial. Peroneal and Sciatic- peroneal. Tibialis Anticus.1 Extensor Digitorum Longug.1 Extensor Hallucis Longus.1 Peroneus Longus.1 1 Muscles chosen for most intensive analysis; the abductor pollicis brevis did not appear in the original standard list and does not figure in either the count of affected muscles now contracting or in the average power of distal muscles. strength of movement. For each affected muscle the examiner was re- quired first to observe voluntary movement visually, and second, if move- ment against resistance was possible, to estimate its strength in quantitative terms, using the spring-scale technique of Lewey (41) or the Newman Myometer (57). The visual observations were classified in accordance with the following scheme: 1. No voluntary contraction is perceptible. 2. Perceptible contraction only. 3. Movement, but not against gravity. 4. Movement against gravity, but not against resistance. 5. Movement against resistance. This classification, it may be noted, is essentially that used by the British Medical Research Council (70) except that in the latter classification movement against resistance is subdivided into "some" and "powerful" resistance. In the present study the power of muscles capable of movement 403930—57- 73

against resistance was scaled in a roughly quantitative fashion, as already indicated, the normal homologous muscle serving as the control. It was thus possible to express strength of movement as a percentage of normal; the muscle unable to move against resistance is rated 0 on this quantitative scale, even if it be capable of movement against gravity. Although a 100-point scale was employed by examiners in making the quantitative ratings, when the resulting data were first tabulated it was found that the ratings centered on multiples of 5 and the scale was accordingly reduced to 20-odd intervals: 00, 01 to 02, 03 to 07, etc. There are certain inherent limitations in the method of examination adopted for the present study. The examiner must be quite expert if he is to guard against substitution and trick movements and he must be well aware of the problem of anomalous innervation. The patient must be a cooperative individual who, through muscle retraining, is capable of volun- tarily activating the muscle. Every examiner has seen patients with good muscle mass and evidence of nerve regeneration, but who have not relearned use of the muscle. This is especially true in the hand where long flexors and extensors are substituted for the small intrinsic muscles of the hand. Not infrequently is the extensor digitorum substituted for the abductor digiti quinti as an abductor of the fifth digit when evidence of regeneration is cited for this muscle. The patient without retraining in the use of the latter muscle continues to substitute the movement acquired during the phase of denervation. In addition, many patients are unable to initiate an isolated movement of a muscle, such as abduction of the fifth digit utilizing the abductor digiti quinti as a prime mover, but will utilize this muscle with good power in association with other muscles when making a fist. During examination, an interval of instruction may enable a patient to contract a muscle against resistance which earlier he was unable to move at all. There are three main factors to be considered in motor recovery following peripheral nerve injury: (1) growth of nerve fibers in both length and diameter; (2) preservation of muscle mass; and (3) retraining in the use of previously denervated muscles. The longer the period of denervation the greater will be the attendant atrophy in affected muscles, and the poorer the level of physical therapy directed at muscle reeducation the more often will voluntary activation fail even in the presence of adequate reinnervation and minimal muscular atrophy. In the upper extremity, where dexterity of movement is a major goal of treatment, physical therapy is characteristically intensive. In the lower extremity weight-bearing and gross movement are the objectives and are early accomplished by the use of a brace or other supporting device. The natural consequence is a less intensive program of muscle reeducation on the part of the physical ther- apist and a lesser expenditure of effort by the patient to relearn the use of reinnervated muscles. Most patients indulge in a passive program of watchful waiting with massage and/or electrical stimulation the only ther- apeutic effort. It is not unusual to see a patient still resorting to a foot- 74

drop brace in the presence of adequate peroneal regeneration, for example. In preparing a summary of the history for both clinical and statistical purposes, care was taken to determine precisely which muscles had been paralyzed by injury and remained so prior to such surgical intervention as was undertaken. In addition, to guard against extraneous influences on the movement of muscles the examiner was required to classify each muscle according to the following scheme: 1. Affected by injury or operation, nerve branch sacrificed. 2. Affected, working tendon transplant. 3. Affected, loss of muscle or tendon substance by direct injury. 4. Affected, with none of the above special features. Only muscles in the fourth category are studied in this chapter. Several methods have been used to combine the observations on individual muscles into various patterns representing, say, all affected muscles on a limb, or all the distal muscles. These auxiliary measures are as follows: 1. Arithmetic average of relative power of groups of affected muscles, separated into distal and proximal groups. 2. Number of affected muscles in standard list (table 48) which now contract, separated into distal and proximal groups. 3. British assessment of motor recovery, an adaptation of the scale used by the Nerve Injuries Committee of the Medical Research Council of Great Britain. In the first two indices each affected muscle has equal weight, but a dis- tinction is made between the proximal and the distal muscles. In the British assessment consideration is given to both proximal and distal muscles and to the entire range of movement and power; it is most useful in high lesions affecting both proximal and distal muscles. The categories of the British scale as used in this study differ slightly from those most recently published (70) by the British group and are as follows: 0. No contraction. 1. Return of perceptible contraction in the proximal muscles. 2. Proximal muscles acting against gravity, no return of power in intrinsic muscles. 3. Proximal muscles acting against gravity, perceptible contraction in intrinsic muscles. 4. Return of function in both proximal and distal muscles of such an extent that all important muscles are of sufficient power to act against resistance. 5. Return of function as in category 4, with the addition that some synergic and isolated movements are possible. 6. Complete recovery. The most recent British scale subdivides category 3, providing for those cases of ulnar injury in which there is recovery in all the ulnar intrinsic muscles as distinguished from those in which there is merely a nicker of action in the hypothenar muscles alone. Also, the British group employs the assessment scale in precisely this form for upper extremity cases only, whereas in this study it has been employed for all nerves without modifi- cation. In the grading of peroneal and tibial lesions the British group rarely encountered cases other than those of category 1 above, and so sub- divided this category by averaging the ratings of the individual muscles on 75

a scale of 0 to 5, corresponding roughly to those employed here in observing the contraction and movement of individual muscles. The presentation of a single case will suffice to illustrate the similarities and differences among the several motor indices routinely utilized in the present study. Case 2080: A radial nerve suture, lower third of the arm, with seven muscles affected, the results of the motor examination at follow-up being as follows: Brachioradialis: Movement against resistance not tested. Extensor carpi radialis: Movement against resistance, measured at 50 percent of normal. Extensor digilorum: Movement against resistance, measured at 65 percent of normal. Extensor carpi ulnaris: Movement against resistance, measured at 0 percent of normal (perceptible movement was, however, present). Abductor pollicis longus: Movement against resistance, measured at 25 percent of normal. Extensor pollicis longus: Movement against resistance, measured at 27 percent of normal. Extensor pollicis brevis: Movement against resistance, measured at 25 percent of normal. The average power ratings are as follows: Proximal muscles: 30-39 percent. Distal muscles: 20-29 percent. The numbers of affected muscles in the standard list capable of contraction, similarly, are: Proximal muscles: 4. Distal muscles: 3. The British assessment is grade 4 on the scale employed here. C. DESCRIPTION OF MOTOR RECOVERY It will be recalled, from the description of the sampling plan on pages 5-13, that the entire sample of 2,720 men studied here includes many with injuries or other characteristics of special interest, and by that token, of possibly atypical prognosis. In planning the tables for this descriptive part of the chapter, therefore, it was considered desirable to restrict the selection of cases to those in the representative sample. The analysis in chapter II (pp. 31-53), showing the differences among groups of cases drawn from the three major groups of rosters, further documents the need for this distinction which was made as follows: 1. All sutured cases were taken from the Army Peripheral Nerve Registry; and 2. Cases from the Registry were excluded if they fell outside the sampling area for the center to which they had been allocated. In addition, about 25 percent of the cases had no follow-up and for any particular muscle the number of injuries available for study depends upon the site of lesion. The descriptive data will be presented in two parts, the first pertaining to the individual muscles and the second to groups of muscles, either proximal, distal, or all combined. All data on individual muscles or groups 7*

thereof are confined to cases in which these muscles were affected by the original injury. 1. Individual Muscles Although some average value may be the most important characteristic of the detailed distribution tabulated for each muscle, such averages provide no information about the often great individual variation seen in particular muscles. Figure 10 provides a graphic summary of the variation observed in the recovery of the abductor pollicis brevis. Relative strength of movement is scaled along the abscissa, and the height of the bars denotes the relative frequency with which muscles were observed to respond with a given strength of movement. The tallest bar, for the interval 0 to 12 percent of normal strength, is divided into three components: 19.5 percent with no contraction at all, 37.5 percent with visible contraction, but not against resistance, and 6.7 percent with movement against resistance rated at 12 percent or less of normal, or 64 percent in all. The remaining 36 percent scatter widely over the range of relative power above 12 percent. The upper line provides a cumulative distribution of the relative frequencies denoted by the vertical bars. The device of the cumulative distribution has been adopted in figure 11 to conserve space and to facilitate visual comparison of the distributions obtained for the various muscles studied here; the underlying data appear in table 49 in the same form except that a distinction is made among muscles unable to contract, those with visible contraction but not against resistance, and those contracting only weakly against resistance. Several properties of cumulative distributions generally may be noted as a guide to the interpretation of figure 11: (a) a rectangular, or flat, distribution having the same relative frequency in every region of the strength scale would appear as a straight line from the origin to the upper right corner; (b) if one cumulative distribution lies everywhere above another it is because the former distribution is more concentrated at the lower end of the strength scale; (c) the cumulative curve rises over a region only to the extent that the underlying distribution contains fre- quencies there, so that a rapid rise in a region denotes some concentration of cases there and a plateau denotes an absence of cases; and (d) a very favorable curve would start near the origin, remain fairly close to the abscissa over much of the range of relative power, and increase rapidly only in the region of normal relative power. As plotted in figure 11, each distribution shows the percentage of affected muscles rated at a specified relative strength or less, the strength being indicated by the horizontal axis. The proximal muscles, in the main, are more variable in their strength of movement and are less concentrated at the lower end of the strength scale. In none of the distributions of figure 11 is the increase a very sharp one in the range of 90 to 100 percent of normal, and in most instances there is little or no increase at all in this region because very few muscles were observed to have normal power 5 years after suture. For only 5 of the 23 muscles do more than 5 percent of the measurements of strength fall in the 77

region of 90 to 100 percent of normal: flexor pollicis longus, flexor digi- torum profundus 2, flexor digitorum profundus 4 and 5, extensor carpi radialis, and gastrocnemius and soleus. These are the most proximal muscles in their respective sets, but not every set is represented because in this series the tibialis anticus, representing peroneal and sciatic-peroneal muscles, does not recover normal power with even this small frequency. At the other end of the scale one finds that the distributions for the most distal muscles in each set usually start with 50 percent or more rated 0 in power, indicating that in 50 percent or more of the cases there is inability to move the muscle against resistance. In the muscles innervated by the peroneal and sciatic-peroneal, however, failure to move against resistance is found in over half the cases for every one of the four muscles charted in figure 11. Although the interest here is in the individual muscle, some comparison among muscles is helpful in understanding the variation in results which may be expected following suture. In the median set, for example, the flexor pollicis longus and the flexor digitorum profundus 2 have almost identical distributions, while that for the abductor pollicis brevis is much less favor- able. The disparity, it may be noted, is not simply confined to the propor- tion of cases in which movement against resistance was possible, but extends to the measured strength of those cases in which such movement was seen. Thus, it was observed that for muscles with movement against resistance, power was 80 percent or better in about 22 percent of the flexor pollicis longus muscles and in only 2 percent of the abductor pollicis brevis muscles. Another noteworthy feature of the distributions exhibited in figure 11 for sutured lesions is that they rarely climb steeply, as such curves do when cases are concentrated at a particular point along the horizontal axis, but usually rise gently and somewhat after the fashion of a rectangular distri- bution, which follows a straight line when plotted in cumulative form. That is, examiners failed to note any real concentration of cases at any point except 0 on the power scale; if movement was made against resist- ance, its measured power might fall anywhere along the scale with almost equal probability. The average power for all the sutured lesions affecting a given muscle is shown in table 50 in systematic form. All the standard muscles are rep- resented, not merely the 23 chosen for most intensive study. Average power is expressed in two forms: (a) all examined cases are included, a 0 rating being assigned to those in which there was no voluntary movement against resistance; and (b) the average pertains only to those in which there was voluntary movement against resistance. The averages are arith- meticaverages, and for descriptive purposes one might in some instances prefera median average value as somehow more representative, particu- larly in the face of a concentration of cases at 0. However, the mean or arithmetic average is an easier statistic to work with in many ways and has been used routinely in this study. Approximate medians may be read off figure 11 as the point on the horizontal axis at which the cumulative dis- 7*

Figure 10. Strength of Movement of the Abductor Pollicis Brevis Following Com- plete Suture of Median Nerve, Strength of Movement Against Resistance, as Percentage of Normal PERCENTAGE 20 40 6O 80 STREH8TH OF MOVEMENT ABAIN3T RESISTANCE: PERCENTAGE OF NORMAL - 50 - 40 - 30 - 20 - 10 100 79

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tribution passes the 50-percent mark on the vertical axis. Thus the median average for the abductor pollicis brevis is at 0, whereas the mean is 14 percent. In view of the poor showing of lower extremity muscles in figure 11, where the impression is based chiefly upon failure to move against resist- ance, it is of special interest to note, in table 50, that these muscles do not appear at such a disadvantage when the comparison is confined to muscles capable of contracting against resistance. That is, the factors responsible for poor motor return in the lower extremity determine chiefly whether there will be contraction against resistance; if such contraction is present, actual power is not very different from that for the muscles of the upper extremity. Table 50 is a reference table, summarizing a great deal of the motor data from the present study. It pertains to all complete sutures in the rep- resentative sample, regardless of site of lesion, type of injury to the nerve, and the like. Site of lesion was classified in accordance with the scheme already pre- sented in chapter II. Although the full detail is of interest, most of the information implicit in knowledge of site is contained in the distinction between high and low sites as defined for this study, i. e., high lesions are those occurring at or above the elbow or, in the lower extremity, involving the sciatic, and low lesions are those below the elbow or below the bifur- cation of the sciatic into peroneal and tibial nerves. Accordingly, syste- matic high-low comparisons are presented first; these appear in table 51 for complete sutures only. No comparison has been made for the radial since virtually all lesions studied here are high. Since only about 85 per- cent of the muscles whose voluntary movement was observed by examiners were actually measured as to strength, any machine table with information on both aspects of motor performance might carry two different numbers differing, on the average, by the indicated amount. Although all compu- tation has of course been based on precisely correct counts of cases, it seemed unnecessary to include both numbers in the tables and accordingly, whenever two counts might have been used, the smaller number (N) was chosen for presentation. There are three aspects to the comparison detailed in table 51.

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Table 50.—Mean Power of Affected Muscles Following Complete Suture Nerve and muscle Number of cases Mean power as percent- age of normal All cases Cases with movement against resistance Median Fl. car. rad Fl. poll. long Fl. dig. prof. 2 Opponens Abd. poll. brev Ulnar Fl. car. uln Fl. dig. prof. 4 & 5 Abd. dig. V Add. poll 1st dors. inteross Radial Triceps Brachiorad Ext. car. rad Ext. dig Ext. car. uln Abd. poll. long Ext. poll. long Tibial Gastroc. & sol Tib. post Fl. dig. long Fl. hall. long Interon Sciatic-tibial Gastroc. & sol Tib post Fl. dig. long Fl. hall. long Inteross Peroneal Tib. ant Ext. dig. long Ext. hall. long Peron. long Sciatic-peroneal Tib. ant Ext. dig. long Ext. hall. long Peron. long 141 103 155 187 124 253 304 425 393 305 39 111 175 167 177 113 169 32 37 53 54 76 125 129 133 133 120 128 137 134 135 166 167 165 168 55.99 33.16 31.13 23.69 13.67 59.57 33.92 9.63 23.66 10.90 57.05 48.56 41.26 28.08 36.07 14.69 19.14 55.94 35.68 10.09 9.44 3.36 46.08 18.72 3.31 2.82 .42 17.38 8.61 6.68 17.00 5.91 2.25 2.36 4.26 46.78 45.95 ') 33.24 44.07 24.81 ') 28.42 C) 49.12 44.66 C) C) 36.76 63.93 0) 35.67 34.00 P) 58.77 ) 36.67 31.25 0) 46.35 31.89 35.80 42.50 31.65 23.50 27.79 26.52 1 Not calculated.

11 * * * * 55 * * ^ -•-1 * * 8 •. CO * • * * E <5 * '§ J q •- u > »• o n in CN oo in 11 o m CN NO NO CO CO CN ON CO O 5 8 0-1 co m c-. 4 ft S-| 3 § s s Ij - NO Sm n •* CO CN 00 oo ?° 2 § in -— 8. a "^ r* m o- •«• OJ CO co CO 5, c O D a n CO O CO CN O co in in NO m in ON NO * 00 ON NO oN 5 NO 3§ 00 CN ri 0 CO | NO •* NO 4 o ON in m CN n NO 00 NO CO ON CO CN H m m m co o ON co 1 ^H T-1 &j. CN m n Tf in •* O 9 ON Q CN 5 01 CN 00 3 S CO •* n t~- OO m oo in |f •* n CN o- m o oN CN NO ON 00 ^- m in ^ VI 1 ON ON ON ON 00 ON ON NO NO m 00 CO CO CO in ao r* ON NO n CN r- co co CO * NO t^ '§ * •* ON NO 2 r- •* m in o bo r- O oo •* m oo o •* & 0 0 •S 0 CN CN CO 00 ON t~- NO r*- r- r- r*~ NO in n NO Tk 0! §5 NO •* in cO cO CO co m 00 CO $ CO s °- 3 S NO •* CN CO CN m m c | c 1 a NO ^ 00 CN •* co CO t~- NO NO 0 01 •* NO ON ON 00 CN m 01 CN "1 ON ON o r~ CO 1 | n r- CN 00 CN CN! n n c* 00 00 NO 00 CO ci -f m CN m co •3 s s^? CN in CN 21 S m 11 NO NO n NO NO m M y oo 00 ij - NO CO o ill NO 00 ON 00 o- m oo oo r- o- NO CO ON ON ^ 00 •u- oo oo r- -^• 00 ON NO & a *• w fl ft 8 CJ Bk -S - CO O O t~- NO NO CO O ON NO 00 NO CN r- •* in ON CO CO CO S N* 15 r- o n n NO CN CN CO ^ 'I 1 1 f 9 I 1 N ?! i| 1 II . : : : t m n I CN 5 Add. poll 1st dors* inteross Inteross o *§ -° 8 bo I ^m Sy p. 53 Q bb g a §! •o '•v a-d •• -! i < So »S E O < o P E 91

s 1 § i \ * » » » » » * » 1 u T I •*•• °-- •a 3 •a , o I • m ON o o in N co oo oo m *O i. u g.l 9 ^o *^ in CN jS * i « ^'i "a * i s * S « 1 1 s . CO •-H 00 O 1 -c* •a < 3 *-t *-1 j I >- fll £ oi ? o m in ^ *-• •M •Jj u 8 bo Oi 1 1 oo r- •* m i » CN CO CO CO 1 | » in O cN eN ^o m t^ m (e 1 ^ o « c *-• co r^ NO I p C C S CO CM CN CN » *S 2 ro ^ asri s D• ta " a Q = O r0 § B . ON CM CO CM £ X '8 ^ 3 in cvi CM •* i 1 1 X) g •>.* Is CO ^ CO C^ C7N ON CO CM =3 .£> gig1 oo CM in in m ••j- co in J g c- o' I J2 £ 2 K 8 vJ -. NO r- m oo 8 .§ NO NO NO NO 5 1 | | JS O ^ » 1 *y || So 1 •a 1 | •2 -S \ J5 •§ § a § 3 g fe o & Q JH «v C v- >. [ f. bo ° 5 a § „ 0 3 n 3-. % G -0 _w t tJ« *^ ^ 3 2 W ^ J3 fl - „

a. The percentage with at least a perceptible contraction, given for the 23 muscles most intensively studied; b. The mean power, expressed as a percentage of normal power, of all cases tested, rating as 0 all those in which there was no movement against resistance; and c. The mean power of only those in which there was movement against resistance. Systematic tests of significance have been made only on the basis of the second of these, the results of which appear in the last column of the table and are uniformity in favor of the low lesions, although not significantly so in all instances. The percentage contracting, on the other hand, does not differ so characteristically between high and low lesions, impressive differences being found only in the lower extremity. The mean power for cases in which there was movement against resistance does not distinguish high and low lesions quite as sharply as the mean for all examined cases, but the general picture is the same except for the tibial, where the propor- tion of muscles moving against resistance is so small for the flexor digitorum longus and the flexor hallucis longus that the corresponding mean values are subject to quite large sampling errors. If one plots the two mean values for each muscle and site of lesion in a correlation diagram, a rather smooth curve will be found to fit the data for the muscles of the upper extremity, suggesting that high-low differences are equally well described in terms of either index. This is not true of the lower extremity for which, in addition, any fitted curve would follow a different path, since it is primarily the mean relative power for all cases which is depressed in the lower extremity. On the whole the data for complete sutures suggest the following general conclusions: a. Motor recovery is better after low lesions than after high, but in the upper ex- tremity the advantage is greatest in the most proximal muscles and doubtful in the most distal. b. In the upper extremity the advantage of the lower lesions is less a matter of the ability of muscles to contract than of actual strength of movement. c. The advantage of the tibial over the sciatic-tibial lesions is chiefly a matter of ability to contract rather than strength of movement, but the peroneal exceed the sciatic-peroneal cases not only in regard to the proportion contracting but also strength of movement for those able to contract. Although the amount of information on lysed cases is not nearly so large as that for the sutured cases it seems important to present it here. Table 52 presents a summary of the data on the representative sample of lysed cases. There was too little information on the median to justify its presentation, the great majority of lysed median lesions having been high in their loca- tion, and not all the ulnar muscles are represented by enough cases to merit separate presentation. The only suggestion of a site effect in table 52 derives from the tibial which is not represented by very many low lesions, and statistical tests do not give this suggestion much weight. It would appear, therefore, that the effect of gross site of lesion is particularly large only for the sutured lesions, not for the lysed. 93

Table 52.—Mean Power of Affected Muscles Following Neurolysis, by Gross Site of Lesion High lesions Low lesions Nerve and muscle Statistical tests ' Number of cases Mean power, all cases Number of cases Mean power, all cases Ulnar Abd. dig. V 57 33.42 27 36.67 NSI Add poll 52 45.00 27 56.85 NSI Peroneal Tib. ant 45 33.78 23 33.91 NSI 35 37.71 25 40.20 NSI Ext dig. long 32 30.63 23 33.70 NSI Ext. hall. long 33 24.24 24 19.58 NSI Peron. long 35 36.29 22 38.64 NSI Tibial Gastroc. & sol 44 64.55 15 64.67 NSI Tib. post 44 39.32 14 49.64 NS Fl. dig. long 48 23.23 16 32.50 NSI Fl. hall. long 47 21.49 18 32.50 NS 38 8.42 14 16.43 NSI 1 Results of statistical tests are abbreviated as follows: NSI=Not significant, by inspection only. NS=Not significant, by formal test. Further detail on the effect of site of lesion is presented in table 53 for sutured cases only. As in table 51, three different indices of motor recovery are employed, although statistical tests were confined to the average power of all tested muscles, whether or not able to contract against resistance. In the median there is no evidence of any uniform gradient associated with site; in the proximal muscles the lowest lesions do best, and in the distal muscle site seems relatively unimportant. There is a suggestion, however, that recovery of the abductor pollicis brevis may be notably poor in the quite high lesions of shoulder and upper third of arm. In the proximal median muscles both the probability of any visible contraction and the power of any contraction against resistance appear to depend on site of lesion. In the ulnar the situation is only roughly similar. For the flexor digitorum profundus there is no real evidence that site has a strong influence on any of the several motor indices. In the abductor digiti quinti, on the other hand, all three indices are sensitive to site, and there is some suggestion of a gradient, with the poorest results found in the highest lesions. Although the statistical tests on the first dorsal interosseus are less

conclusive than those on the abductor digiti quinti, the data are roughly similar. A word is required here on the nature and limitations of the statistical tests employed. It is a cardinal principle in the theory of testing hypoth- eses that the hypothesis be framed independently of the data upon which it is tested. In the present application, the hypothesis chosen for testing, in advance of the calculation of the motor indices, was merely that recovery is independent of site. The probability results obtained in these tests, then, apply only to this hypothesis and not to others which might reason- ably have been proposed. In only one of the radial muscles, the extensor digitorum communis, do the data of table 53 suggest any important variation with site of lesion. Both the proportion contracting and the power of muscles moving against resistance increase as the lesion advances distally, but only for power is the observed variation statistically significant by the criterion employed here. The peroneal and sciatic-peroneal nerves are studied separately, with the sites as shown in table 53. Statistically significant variation was noted only for the tibialis anticus in sciatic-peroneal lesions and for the extensor digitorum longus in peroneal lesions. Apart from the high-low difference already discussed the only evidence of any general effect of site is seen in the proportion of sciatic-peroneal muscles able to contract at least mini- mally; power seems surely involved only in the tibialis anticus. The varia- tion seen in the peroneal is unimpressive, for the statistical conclusion of heterogeneity in the extensor digitorum longus rests upon rather slender grounds. In the tibia! and sciatic-tibial nerves, as may be seen from table 53, site of lesion seems to be clearly a factor in the probability of contraction for the flexor digitorum longus and the flexor hallucis longus, but not in the relative strength of the muscles able to move against resistance. Type of lesion was classified in accordance with the scheme presented in chapter II, but in this clinical series the type of lesion cannot be divorced from surgical handling. The surgeon who appraises an injured nerve will generally confine his intervention to a neurolysis only if the nerve remains in continuity and appears relatively undamaged, and will perform a com- plete suture on a lesion in continuity only if he believes considerable dam- age to have been done. Accordingly, the comparisons permitted by the clinical material are as follows: a. Within the set of complete sutures, and on the basis of the operator's observation of the gross external appearance of the lesion and the appearance of the cross section, a distinction may be made between apparently complete and apparently incomplete lesions. b. Complete sutures, partial sutures, and lyses may be compared with the under- standing that it is primarily the type of lesion which distinguishes these three operation groups. c. Within the set of lysis cases, a distinction may be made between nerves judged essentially normal and those thought by the operator to exhibit some scarring or neuroma formation. 95

^ O CN r- o T-I O t- m co cs m in o d T^ tn « co CM CN CM 2 O CO •* 00 CO ^-i * •- CO * 8-* NO m CM CO t^ o NO d o CO CM 5 •- i i m co oo CO CN! cs CO 2 00 O r* * NO r* O * »H CO -* o m CM * O ON O 00 f •o CM CM' m m NO r*- oo oo ^ *-v oo CO CM' ^ CM •CH •& ij - m ^ m ON CO T* •* CNl 15 in ON NO ON •* CM -s.lc.-e* 2 oo •— tc S ^•^Nj. 1 ct^ | 1 ^B cf s >^ A M CO T-I m o oo ~ CM' CO CO ON 00 £ oo m O ON r- n oo ••j- in r- •* CM CNl 0N J5S CO *-! CO ON CO m co 8 T-H OO CM O * m oo NO CO • * CM s I a 3 ll 0 -O e Si S I Lower % 1 Middle % Statistical I u a 2 •3

These different comparisons will be discussed in turn. Lesions treated by complete suture were classified as either complete divisions, partial divisions, or neuromas in continuity, but in tabulations on type of injury these three groups were reduced to a dichotomy between complete and incomplete lesions. Neuromas in continuity dominate the incomplete lesions; in the entire set of 2,556 sutures among all 3,656 lesions studied here, 68 percent were classified as complete divisions, 6.5 percent partial divisions, 25 percent neuromas in continuity, and 0.5 percent other or unspecified types of lesion. Table 54 provides a complete summary of the information available on type of lesion, and provides no evidence of any effect of type of lesion, provided a complete suture was done. Only in 3 out of 36 tests was a significant discrepancy noted, and the differences between pairs of means do not seem especially one-sided in their distribution. Table 54.—Mean Power of Affected Muscles Following Complete Suture, by Type of Lesion Complete lesions Incomplete lesions ' Statis- tical tests' Nerve and muscle Number of cases Mean power all cases Number of cases Mean power all cases Median Fl car rad 98 73 107 131 85 56.28 31.99 31.78 20.69 12.47 30 22 54.67 36.59 26.43 31.59 14.44 NS NS NS FI. poll. long . . Fl. dig. prof. 2 35 41 27 Opponens * Abd. poll. brev NS Ulnar 180 217 308 278 230 58.97 35.03 8.62 22.82 10.76 55 66 91 91 60 61.45 30.33 12.82 NS Fl. dig. prof. 4&5 NS NS NS NS Abd. dig. V Add poll 25.88 12.08 1st dors. inteross Radial Xriceps 27 83 132 126 135 85 126 77 50.37 43.67 39.51 27.30 33.78 14.94 18.06 15.00 12 72.08 63.04 46.63 30.49 43.45 13.93 22.33 15.26 * * NS NS NS NS NS NS Brachiorad . 28 43 41 42 28 43 19 Ext. car. rad Ext. dig Ext. car. uln Ext. poll. brev See footnotes at end of table. 100

Table 54.—Mean Power of Affected Muscles Following Complete Suture, by Type of Lesion—Continued Complete lesions Incomplete lesions ' Nerve and muscle Statis- tical tests' Number of cases Mean power all cases Number of cases Mean power all cases Peroneal Tih* ^nt 78 83 81 84 14.81 7.47 6.11 50 54 53 51 21.40 10.37 7.55 22.65 NS Ext. dig. long NS NS Ext. hall. long Peron. long . . . 13.57 * Tibial Gastroc. & sol 18 21 34 35 52 62.50 40.24 12.21 9.57 3.46 14 16 19 19 24 47.50 29.69 6.32 9.21 3.13 NS NS NS NS NS Tib. post Fl. dig. long F). hall long Inteross Sciatic-peroneal Tib. ant 116 116 113 115 5.39 50 51 52 53 7.13 2.16 3.65 5.28 NS NS Ext. die. lone . . 2.28 1.77 3.78 F-xt. ha"- l«"g * NS NS Peron. long . . Sciatic-tibial Gastroc. & sol 87 91 93 93 86 46.67 16.65 2.04 2.15 0.58 38 38 40 40 34 44.74 23.68 6.25 4.38 0.00 NS NS NS Tib. post FL dig. long n. hall. long ...... NS NS Inteross 1 For the median and ulnar, incomplete lesions are confined to neuromas in con- tinuity; for other nerves they include partial divisions. 1 Results of statistical tests arc abbreviated as follows: NS = Not significant *=Significant at .05 level. Lysed and completely sutured cases are compared in table 55; separate comparisons are made in table 55 for high lesions and for low lesions in the case of muscles in which there are important high-low differences, since sutured and lysed cases are not always homogeneous as to the pro- portions classified as high and low. Although the only probabilities shown in table 55 are based on tests of means for all cases, including as 0 those not contracting against resistance, parallel tests were also done on 101

f I 3- cS § g <* ll •§ a .8P c3 i m P CO g I o> 3 * IX IX 1 1 S o o o r*- m c o 00 C^ O ON ON ON OO*-*OOT-iOOCOOOO in co co T-I •-i CM T* ONONONOOONOOONOO o ON o CM CM CM CNl *-• CN) T^ cO ON ••f vO m CM C^ cO cO vd O CO §r- cN o - m C M ov *-• T*•^* NO iO O CM T}- co CO •* O **• 00 CM 00 ui O cO ON C^ ON 00 O 00 ^ ON d 10 Tf *-i • 00 ON r*^ ^ ^-i r- oo o in cO CM 00 ON m co CM •-i c s ^H c*^ vO NO TH •* O O ON ON B. S S d . V 4) Q 1 • Pf*l3 •s •s 2 8 •S. e M 101

•s* « * w * « » Z * ~ •*• — «i ON !*• NO NO NO t- o o oo •* CNI t-- m NO CN cO ^-• 00 CO Csl CNl §O o o •-i*-i co r* r* §vo o\ go 10 vo O Ov ON 8 8 o ^- 00 e*l 00 ^i 1-H •«* oo m • m NO NO ON CS «1 Csl 00 CN] T-l C*J ON! O r* cO 00 •* NO 00 C*i CN! O §^C OO 1-H *-l 8 OO O t^ ON Tf ON NO NO CN! O C•1 ^ CO ON ON ON co Csl NO NO 1-H NO m TH NO NO CO O . Si 3 i I c. a* 3 •£ oo O O oo oo m § ° J3 ** *• C H««(ii B> o 3 £ bo S^^-2 3 T3 X c ji - « 8 H « « (SJ O H E E^ 103

the proportions contracting and with about the same results. It is readily apparent from table 55 that the advantage of the lysed cases is twofold— the probability of contraction is higher and the muscles which do contract against resistance have more power. It is also of interest to note that the advantage is not limited to proximal muscles, but extends with equal force to distal muscles. The comparisons in terms of mean power obscure the fact that the sutured and lysed cases both extend over the entire range of power from 0 to 100 percent, differing only in their relative concentra- tion at different regions of the scale. The lysed cases studied here, it may be noted, are those in which the clinical record contained definite evidence of denervation immediately prior to operation. By way of interpretation it may be noted that neurolysis in any particular form is done whenever the surgeon believes that the total situation promises a higher degree of recovery if he virtually leaves the nerve alone than if he subjects it to resection and suture. The details of this complex evaluation are discussed in chapter XII. The statistics presented here simply reflect the soundness of the surgical judgment and must not be considered a comparison of competing forms of surgical therapy. In a study of late results there is no way to evaluate the possible role of neurolysis in the relief of acute nerve-segment compression, as by a band of scar tissue. The cases with neurolyses may even appear in a slightly more favorable light in such a survey than they should, since instances of mistaken judgment will often lead to resection and suture after a long delay, a delay which would tend to lower the average results of suture. In the representative sample only 1 percent of the first complete sutures had been preceded by lyses. The excellent recovery of the neurolysed cases does demonstrate that some lesions causing total dysfunction can, in due time, permit far better regeneration than can be effected by suture. This recognition by the surgeon at nerve operation is the critical point at issue, and the criteria governing his decision are discussed in chapter XII. The magnitude of the discrepancy between lysed and sutured lesions is by no means uniform for all nerves and muscles and for the several indices of recovery. For sutured lesions of the upper extremity the average percentage with at least minimal contraction is, on the average, about 94 percent of that observed for parallel lysed cases, but for the lower extremity no simple average will describe the relationship, and no curve fits the data well. The average power of muscles capable of movement against resistance following suture is about 74 percent of parallel values for lysed lesions, but the scatter is too great for any single average, or any fitted curve, to have much meaning. Partial sutures were, of course, done only rarely and on lesions which operators regarded as surely partial in extent. Table 56 provides com- parative data for complete sutures, partial sutures, and lyses, for those nerves for which there were at least 10 cases with partial suture. Although no formal tests were done on these data, there is a clear suggestion that 403930—57 -9 10S

a ial sutures occupy a position intermediate between complete sutures and lyses. For the 20 muscles included in table 56 the average ranks of the three treatment groups10 are Complete suture 1.2 Partial suture 1.9 Lysia 2.9 where 3 represents the greatest average power. Most lysed cases were described by surgeons as "normal nerve compressed by scar," but a significant number were called neuromas in continuity and a few partial divisions, and it is of interest to explore the prognostic significance of these descriptions by the operator. In the statistical tests, which are summarized in table 57, it was assumed that cases classified as "normal nerve compressed by scar" must be at least as good as those called neuromas or partial lesions; that is, one-tailed tests n were done. Even on the more powerful one-tailed basis, however, only 3 of the 17 differences were found to be significant, and although the mean is usually higher for the nerves operators regarded as normal in appearance, one can hardly call the evidence in their favor conclusive. Of equal interest is the fact that relative power is usually less than 50 percent even in muscles affected by lesions in normal-appearing nerves; the highest mean is 75 percent. Plainly the operator was unable to detect the damage done to the grossly intact nerve. Age at injury is sharply restricted, not merely by the fact of military service but even more particularly by the fact that the men were predominantly battle casualties. The possible effect of age was sought only for ulnar lesions and by correlating age and relative power. None of the resulting correlation coefficients was impressive, and although several of them seemed significantly different from 0 in the narrow sense of a statistical test, their overall average is only +0.12, too low to be of any real interest and contrary to expectation in sign. 2. Groups of Muscles The previous section is concerned entirely with the individual muscle. Two methods of grouping have been attempted, chiefly for descriptive purposes: (a) that in which the affected muscles on the limb of a particular individual are characterized as a group; and (b) that in which representa- tive muscles innervated by a given nerve are averaged on the basis of average values for each muscle. 10 Each set of 3 means was ranked 1, 2, and 3, where 1 represents the lowest and 3 the highest, mean power, and the 20 such ranks for each operation-group were then averaged to the figures shown. " Most statistical tests on two sample means, percentages, etc. done in testing hypoth- eses for this study are two-tailed* i. e., the null hypothesis will be rejected whenever the difference is sufficiently large, regardless of its direction, but one-tailed tests have been performed in certain instances when one was willing to reject the null hypothesis only if the difference lay in a predetermined direction. 10*

Table 56.—Mean Power of Affected Muscles Following Definitive Operation, by Type of Operation Type of operation Nerve and muscle Complete suture Partial suture Neurolysis Number of cases Mean power, all cases Number of cases Mean power, all cases Number of cases Mean power, all cases Median Fl. car. rad 141 103 155 187 124 55.99 33.16 31.13 23.69 13.67 10 9 12 17 10 60.50 16.67 18.33 32.06 21.50 53 47 59 62 43 73.40 64.47 57.03 36.61 23.14 Fl. poll* long Fl. die. prof. 2 Abd. poll. brev Radial Ext. car. rad 175 167 177 113 169 96 41.26 28.08 36.07 14.69 19.14 15.05 10 12 46.00 43.75 47.27 20.00 16.25 14.29 23 29 26 18 28 16 58.70 51.90 53.85 35.56 32.68 34.38 Ext. dig Ext. car. uln 11 10 12 Abd. poll. long Ext. poll long Ext. poll. brev 7 Peroneal Tib. ant 128 137 134 135 17.38 8.61 6.68 17.00 16 19 20 11 44.69 18.16 14.50 41.82 25 23 24 22 40.20 33.70 19.58 38.64 Ext. dig long .... Ext. hall long Sciatic-tibial 125 129 133 133 120 46.08 18.72 3.31 2.82 .0048 11 12 12 12 10 55.91 33.75 13.75 11.25 2.00 44 44 48 47 38 64.55 39.32 23.23 21.49 8.42 Tib post Fl. dig long Fl. hall. long 107

Table 57.—Mean Power of Affected Muscles Following Definitive Neurolysis, by Type of Lesion Normal nerve compressed by scar Neuroma and partial division Statistical tests i Nerve and muscle Number of cases Mean power, all cases Number of cases Mean power, all cases Median Fl. car. rad 35 75.14 63.45 60.95 40.64 22.95 23 23 27 29 26 71.30 68.70 54.07 35.52 31.92 NS NS NS NS NS Fl. dig. prof. 2 29 37 39 22 Abd. poll. brev Ulnar Fl. car. uln 29 35 47 44 39 65.86 61.43 37.02 52.73 35.38 26 28 37 33 28 57.69 49.64 33.65 47.12 35.71 NS NS NS NS NS Fl. dig. prof. 4&5 Abd. dig. V Add. poll 1st dors. inteross Sciatic-peroneal Tib. ant 23 20 57.17 40.75 43.75 14 14 13 18.21 18.57 24.62 ** Ext. dig. long NS Pcron. long 24 * Sciatic-tibial 32 34 34 23 72.50 25.74 22.94 10.87 14 15 15 15 53.21 12.00 10.67 5.00 * NS NS Fl. hall. long Inteross * 1 Tests were one-tailed, attributing to chance any apparent advantage of neuromas and partial lesions except that tests on median muscles were done on three means corresponding to normal nerve, neuroma, and partial division, and without regard to the pattern of variation among them. Results are abbreviated as follows: NS=Not significant *= Significant at .05 level **=Significant at .01 level.

The simplest pattern of recovery for the individual patient is the count of affected muscles which at follow-up were found to contract. The mus- cles considered are those listed in table 48, except that the abductor pollicis brevis was not used, and separate counts were made for the proximal and distal muscles as well as for both proximal and distal combined. In com- plete lesions, the number of affected muscles is determined, of course, by level of injury and by the particular selection of representative muscles for this study. For complete sutures, table 58 summarizes the tabulated data in distribution form, for those numbers of affected muscles which are rep- resented by sufficient cases to warrant study. In the median, ulnar, and radial it is most usual for all affected proximal muscles to contract, the per- centages ranging from about 75 to 90. In the peroneal and tibial lesions all affected proximal muscles were found to contract in about 50 percent of the cases, and in the sciatic about 25 to 30 percent. Only in the peroneal and sciatic-peroneal is there an appreciable percentage in which none of the affected proximal muscles contracts. The distal muscles are often single muscles, and the concept of pattern applies here only to the ulnar and radial, with three distal muscles each. The distributions seem only somewhat less favorable than those for the proximal muscles. Table 58 also contains the distributions for proximal plus distal muscles. It must be borne in mind that the number affected is, of necessity, the most distal set of that number in the standard list. Thus a complete median lesion with a single standard muscle affected is a low lesion, and the muscle necessarily the opponens. Two features of table 58 are worthy of some discussion. One is the fact that the percentage of ulnar and radial lesions in which all affected proximal muscles contract does not vary much by the number of proximal muscles affected, while for proximal plus distal muscles such is not the case. Two factors play a role in this discrepancy. First, all proximal muscles tend to contract to such an extent that it makes little difference how many are combined into a set; all are high lesions and site is not critical. Second, when proximal and distal muscles are combined, sets of cases with different numbers of affected muscles now vary considerably by site of lesion, which of course has a large effect upon the probability that distal muscles, at least, will contract. In the ulnar, for example, the only cases with all five standard muscles affected are those with site at or above the upper third of the forearm. Another feature of interest in table 58 is the evidence it provides that the recovery patterns of affected sets of muscles are not chance patterns, but that the affected muscles are correlated with one another in their likelihood of recovery. This is shown roughly in table 59 by the comparison of the proportions observed with no and with all affected muscles contracting and the proportions expected if the likelihood of recovery were independ- ent from muscle to muscle. The expected values are crude in that site of lesion was not taken into account in their calculation, but the effect of this

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Table 59.—Observed and Expected Percentages of Complete Lesions With All and With No Affected Muscles Contracting at Follow-up Percentages of lesions Number of Number of Observed Expected Nerve affected lesions muscles No All No All muscle muscles muscle muscles contract- contract- contract- contract- ing ing ing ing Median 4 94 4. 3 67.0 0.0 64.0 Ulnar . . . 3 59 8. 5 83.0 0. 3 63. 5 4 24 0.0 87.5 0.0 59.8 5 222 1.4 69.8 0.0 57.7 Radial 6 16 6.2 75.0 0.0 39.6 7 62 4.8 70.9 0.0 36.5 8 24 0.0 62.5 0.0 36.5 Peroneal 4 137 21.2 47.4 1. 1 19.2 Soiatic-peronral . 4 170 35.9 31.8 6.8 4.9 refinement would not be great, and would increase some discrepancies while decreasing others. The proportion of affected muscles found to contract is not a powerful tool for exploring the effects of various characteristics of the lesion, but in view of the interest which attaches to the comparison of lysed and sutured lesions table 60 has been prepared to make this comparison on the basis of proximal muscles. The lysed cases have some advantage in every set of cases and although the difference is not always statistically significant there can be no doubt of a general discrepancy of important magnitude, most marked in the lower extremity. Groups of muscles have also been characterized, for a single individual, by the mean power of all affected proximal muscles and of all affected distal muscles. As indicated by table 58, the latter index is of particular interest in ulnar and radial lesions, since each of these is represented by three distal muscles. Table 61 contains a summary of all the data on the proximal muscles affected by complete sutures, and shows the average power of the affected proximal muscles on a given limb to be a highly variable quantity. There is little difference among the three major nerves in the upper extrem- ity, but of course their distributions are much more tavorable than those for nerves of the lower extremity. The two tibial components are definitely superior to their peroneal counterparts, and the common peroneal has a definite advantage over the sciatic-tibial. Gross site of lesion was also studied, in sutured lesions, on the basis of the average power of proximal muscles, with a result consistent with that obtained with the individual muscles. Type of lesion was ob- 112

Table 60.—Comparison of Lysed and Completely Sutured Lesions as to Percentage With All Affected Proximal Muscles Contracting at Follow-up Number of affected muscles Completely sutured Lysed Nerve Number of lesions Percentage with all muscles contracting Number of lesions Percentage with all muscles contracting Median . . ... 3 106 317 105 49 34 132 137 170 75.5 89.0 81.0 79.6 52.9 23.5 47.4 31.8 49 72 8 10 16 48 21. 35 89.8 97.2 100.0 100.0 93.8 64.6 71.4 80.0 Ulnar 2 4 5 4 4 4 4 Radial Tibial Sciatic- tibial Peroneal Sciatic-peroneal Table 61.—Percentage Distribution of Completely Sutured Lesions by Mean Relative Power of Affected Proximal Muscles Mean power Nerve M U R P T SP ST 0-9 11.2 12 5 18 0 51 2 21 6 80 1 31 5 10-19 13.0 8.6 7.9 16 3 27 5 9 3 23 8 20-29 9.9 9.6 9.0 11.4 11. 8 4 6 18.5 30-39 8.7 8.3 9.0 5.7 5.9 1. 3 7 7 40-49 16. 1 10.2 12.4 7.3 13.7 2.6 6.2 50-59 7.5 12.2 12.4 4.9 5 9 2 0 6 2 60-69 15.5 10.9 14.6 1.6 3.9 0 2 3 70-79 3.7 9.9 7.9 1.6 5.9 0 1 5 80-89 4. 3 7.9 5. 1 0 2.0 0 8 9. 9 9 9 3 9 o 2 0 0 1 5 Total 99.8 100.0 100. 2 100 0 100. 2 99. 9 100 0 Number of cases. . . . 161 303 178 123 51 151 130 served to have no effect on the mean values for complete lesions. Lysed and sutured cases, however, were observed to differ quite significantly and table 62 presents some comparative data in support of this conclusion. Statistical tests of homogeneity were usually made on the basis of a more detailed classification of relative power than is provided by table 62. The third evaluation of the pattern of motor recovery for the individual case was made on the basis of the modified British classification of motor 113

recovery already discussed. Great importance must be attached to this assessment as being the most summary motor statement on the regeneration of the nerve as a whole. It may, however, be debated whether the classi- fication, in the sense of a scale, has precisely the same meaning for every major nerve to allow meaningful comparisons among nerves. Table 63 provides information on the British classification for all complete sutures and separately for high and low sutures on the median and ulnar nerves. The importance of at least gross site of lesion is reflected in the distributions of table 63. Lower lesions always do somewhat better, although in the ulnar the difference between high and low lesions is the least of all. To the extent that the ulnar, median, and radial may be compared on the basis of this scale, the radial makes by far the best showing if the com- parison is confined to high lesions. Ulnar lesions are similar to median if they are high, but below the elbow they do not do nearly so well. The tibial lesions appear to recover better than the peroneal, in these com- parisons, and the sciatic-tibial better than the sciatic-peroneal. Table 62.—Comparison of Lysed and Completely Sutured Lesions as to Per- centage With Stated Average Power of All Affected Proximal Muscles Range of relative Lysed Per- Sutured Per- Nerve power compared Number centage Number centage of with of with lesions stated lesions stated average average power power Median . . An 71 7 1 A1 jt n Ulnar f.A 1 -in-a Radial 11 A7 7 i 70 Peroneal 25 T> 0 1 7^ Tibial 10 70 o Sciatic-peroneal 33 75 R 1 51 1Q 0 Sciatic-tibial 20 or more 44 75.0 130 44.6 The distributions of table 63 bear little relation to the 5 year results recently published by the British group, and although such discrepancies can hardly be explained they can at least be exhibited and center variation in the United States material explored. In addition, there are a few small differences between the 1954 British version of the classification and the United States modification adopted for this study in 1949, and clarity will be served by presenting the two classifications in parallel, as follows: 114

U. S. Modification 0. No contraction. British* 1954 0. No contraction. 1. Return of perceptible contraction, proximal muscles only. 1. Return of perceptible contraction, proximal muscles only. 2. Proximal muscles acting against gravity, no return of power in intrinsic muscles. 1 +. (Median) Proximal muscles able to contract against gravity, but par- alysis of the thenar muscles. 1 + . (Ulnar) Proximal muscles able to contract against gravity, but par- alysis of the intrinsic muscles of the hand. 3. Proximal muscles acting against gravity, perceptible contraction in intrinsic muscles. 2. Return of perceptible contraction in both proximal and distal. + . (Ulnar) Recovery in all ulnar in- trinsics, more than mere flicker in hypothcnar muscles. Return of function in both proxi- mal and distal muscles of such extent that all important muscles are of sufficient power to act against re- sistance. 3. Return of function in both proximal and distal muscles of such extent that all important muscles are of sufficient power to act against re- sistance. 5. Return of function as above, with the addition that some synergic and isolated movements are possible. 4. Same as category 3, with addition that all synergic and isolated move- ments are possible. 6. Complete recovery. 5. Complete recovery. Detailed comparisons of the United States and British results are made in tables 64, 65, and 66 for the median, ulnar, and radial nerves. The only consistent difference involving all three nerves pertains to the complete failures—although there are not many in the United States series there are none in the British. The United States ratings are considerably more favorable for the median and ulnar, the British for the radial. The differ- ence between the two series of ulnar lesions may be influenced in part by the failure of the United States modification to contain a counterpart of the British rubric 2+. The fact of considerable variation between the two series lends additional interest to the extent of the variation noted among the five United States centers. The general subject of center variation in the United States series was discussed in chapter I (pp. 21—22). The comparison of centers in this respect was made on the basis of all lesions treated by complete suture in an effort to make it as powerful as possible, but at the cost of some loss of homogeneity in the underlying clinical material. Table 67 provides the data resulting from this study. Subdivision of the United States sample in this way naturally subjects the distributions to much greater sampling error, but it seems clear that the differences between the United States and British series are of the same order of magnitude as those seen among II*

Table 63.—Modified British Classification of Motor Recovery Following Complete Suture, by Nerve Nerve and gross site Percentage distribution on British classification ' Total cases 0 1 2 3 4 5,6 Total Median: High 1.6 5.5 13.7 16.9 11.0 25.0 22.9 24.0 37.9 34.2 36.3 27.4 13.0 23.1 7.6 13.2 29.8 29.4 29.6 31.7 38.3 34.6 24.4 18.1 16.5 5.9 5.9 12.9 99.9 100.0 100.0 100.0 100.1 100.0 100.0 100.0 100.1 99.9 100.0 124 109 233 240 193 433 197 138 91 170 136 Low 31.2 21.5 10.4 16.1 12.9 21.3 7.2 7.7 1.8 2.2 Total 3.4 2.5 4.7 3.5 4.6 20.3 15.4 37.6 6.6 7.3 8.3 1.6 5.3 8.1 28.3 15.4 32.9 18.4 14.2 9.2 5.2 7.4 14.2 13.0 22.0 14.1 53.7 Ulnar: High Total Radial Peroneal Tibial 1 The rubrics of classification are as follows: 0 No contraction at all 1 Return of perceptible contraction, proximal muscles only 2 Proximal muscles acting against gravity, no return of power in intrinsic muscles 3 Proximal muscles acting against gravity, perceptible contraction in intrinsic muscles 4 Return of function in both proximal and distal muscles of such an extent that all important muscles are of sufficient power to act against resistance 5 Return of function as in 4* with the addition that some synergic and isolated movements are possible 6 Complete recovery. Table 64.—Comparison of United States and British Ratings of Motor Recovery, Complete Sutures on Median Nerve Code symbols Percentage distributions United States modification British, 1954 United States cross section British, 5-year results 0 0 3.4 0 1 1 7.3 3.8 2 1 + 14.2 32.8 3 2 24.0 30.7 4 3 29.6 14.1 5+6 4+5 21.5 18.6 Total 100.0 100.0 Number of lesions. . . . 233 290 1U

the five United States centers. It will be noted, however, that each of the United States centers classified at least a few cases as absolute failures. In general the variability seen among centers in the classification of motor recovery in this fashion greatly exceeds that observed in determina- tions on the relative power of individual muscles. Table 65.—Comparison of United Stales and British Ratings of Motor Recovery, Complete Sutures on Ulnar Nerve Code symbols Percentage distributions United States modification British, 1954 United States cross section British, 5-year results 0 0 3.5 0 1 1 5.3 0 2 1 + 7.4 5.3 3 2,2+ 36.3 75.5 4 3 34.6 14.3 5+6 4+5 12.9 4.9 Total 100.0 100.0 Number of lesions .... 433 384 Table 66.—Comparison of United States and British Ratings of Motor Recovery, Complete Sutures on Radial Nerve Code symbols Percentage distributions United States modification British, 1954 United States cross section British, 5-year results 0 0 4.6 0 1 1 8.1 10.5 2 1 + 14.2 0 3 2 27.4 28.0 4 3 24.4 24.6 5+6 4+5 21.3 36.9 Total. . 100.0 100.0 Number of lesions .... 197 114 M7

Table 67.—British Classification of Motor Recovery Following Complete Suture, by Center Percentage distribution as to motor recovery ' Total number of lesions Center 0 1 2 3 4 5 6 Total 1. Median Boston 0 13 0 21.7 34 8 17.4 13 0 0 99.9 46 Chicago 3.8 11.5 19 2 23.1 19.2 19.2 3.8 99.8 26 New York 6.7 6.7 10.6 39.4 30.8 4.8 1.0 100.0 104 Philadelphia 9.3 5.1 14.4 25.4 22.9 22.0 .8 99.9 118 San Francisco 0 2.2 8.7 2.2 52.2 32.6 2.2 100. 1 46 Total 5.6 6. 8 13 8 27.6 28 2 16.8 1.2 100.0 340 2. Ulnar Boston 5 9 8.8 16 2 27 9 33 8 7.4 0 100 0 68 Chicago 5 4 5.4 3 6 19 6 62 5 1.8 1.8 100. 1 56 New York 4. 1 2.7 5.4 57.4 29. 1 1.4 0 100. 1 148 Philadelphia 2.9 3.4 7.3 37.6 28.8 19.0 1.0 100.0 205 San Francisco 1.2 4.9 1.2 33.3 42.0 16.0 1.2 99.8 81 Total 3.6 4.3 6 6 39 2 34 8 10.8 .7 100.0 558 3. Radial Boston 9.3 5.6 25 0 19.4 27 8 13 9 0 100 0 36 Chicago 6.7 6.7 16.7 16.7 23.3 20 0 10 0 100 1 3O New York 4.3 10.6 8.5 40.4 31.9 4.3 o 100.0 94 Philadelphia 3.0 7.5 17.9 20.9 19.4 31.3 0 100.0 67 0 11.4 8.6 25 7 28 6 22 9 2.9 100 1 35 Total 4.2 8.8 14. 1 27.9 26 7 16 8 1.5 100 0 262 1 See table 63 for the rubrics of classification. The influence of type of lesion was also explored by means of the modified British classification, with the same conclusion as that already reached on the basis of individual muscles, namely, that severed nerves and lesions in continuity, both sutured, are indistinguishable at follow-up. Incomplete lesions treated by lysis, however, were found to differ quite significantly from those treated by complete suture. Table 68 presents the data on lyses which may be compared with the information of table 63 on complete sutures. It was noted on page 105 that comparisons of sutured and lysed

lesions in terms of mean relative power at follow-up tended to obscure the important fact that the distributions do not lie in different regions of the power scale but are merely concentrated differently. The full distributions of tables 63 and 68 will permit further analysis of sutures and lyses along these lines, e. g., to show how often lysis was followed by recovery which seems poorer than that usually expected from suture. Further information on the influence of site is contained in table 69 for complete sutures on the median, ulnar, and radial. In the median it would appear that the influence of site does not follow a simple gradient, but is specific in the region of the forearm, wrist, and hand, lesions in the lower one-third of the forearm making the best recovery. There were in the entire sample 42 so-called multiple lesions, or injuries to more than one site on a single nerve, of which 26 involved severance plus another injury and 32 were completely sutured. Among the latter there were 28 with follow-up adequate to permit coding of the modified British motor classification, with the result shown in table 70. Although all but one nerve is represented and the cases are very few, it is plain that the multiple lesions did much less well than other sutures. If the expected distribution of these 28 cases is calculated from the data of table 63, one finds the overall discrepancy exhibited in table 71. Table 68.—Modified British Classification of Motor Recovery Following Neurolyris, by Nerve Percentage distribution on British classification ' Nerve and gross site Total cases 0 1 2 3 4 5,6 Total Median: High 0 6.7 1.3 4.7 0 3.8 12.5 6.7 11.4 14.1 20.0 15.2 29.7 0 24.1 39.1 66.7 44.3 100.1 100.1 100.1 64 15 79 Low Total Ulnar: High 1.4 0 1.0 6.1 8.0 0 7.9 0 1.4 0 1.0 6.1 8.0 8.3 10.5 14.0 2.8 6.1 3.8 6.1 12.0 16.7 15.8 24.0 19.7 24.2 21.2 18.2 20.0 16.7 15.8 34.0 31.0 27.3 29.8 33.3 36.0 29.2 31.6 16.0 43.7 42.4 43.3 30.3 16.0 29.2 18.4 12.0 100.0 100.0 100.1 100.1 100.0 100.1 100.0 100.0 71 33 104 33 25 24 38 50 Low Total Radial Peroneal Tibial Sciatic -peroneal Sciatic-tibial 1 See table 63 for the rubrics of classification. 119

Table 69.—Modified British Classification of Motor Recovery Following Complete Suture,1 by Specific Site of Lesion, for Median, Ulnar, and Radial Nerves Specific site Percentage distribution on British classification ' Total cases Median 0 1 2 3 4 5,6 Total Shoulder, upper }i arm . Middle J-£ arm 3.7 5.4 16.7 12.5 22.2 17.9 29.6 16.7 11.2 5.4 100.1 100 1 54 56 23 2 35 7 Lower J£ arm 0.0 5.0 10.0 32. 5 32 5 20 0 100.0 40 Elbow* upper }{ forearm . Middle ^ forearm 7.3 7.3 0.0 18.2 7.7 25.5 23. 1 27.3 32.7 14.5 30.8 100.1 100. 1 55 52 Lower % forearm, wrist, hand 5.8 9.2 2.3 9.2 29.9 27.6 21.8 100.0 87 Total 5.8 7.0 14.0 27. 3 28. 5 17.4 100.0 344 Ulnar 0 + 1 2 3 4-6 Total Upper }£ arm 24. 14 10. 34 39.66 25.86 100. 00 58 Middle f t arm 11.48 11.48 36.07 40.98 100. 01 61 4 29 5 71 45 71 44 29 100.00 70 Elbow .... 4 00 10 00 28 00 58 00 100.00 50 Middle % forearm and 6.90 0 32.76 60.34 100.00 58 5 93 7 41 3 48 51 85 100 00 135 Total 8.80 7.41 36.34 47.45 100.00 432 Radial 0 1 2 3 4 5 + 6 Total Shoulder, upper }{ arm . Middle }{ arm 5.2 3.9 10.3 20.7 13.6 31.0 22.4 10.3 17.5 99.9 58 103 8.7 21.4 35.0 100. 1 Lower % arm and below. 3.8 8.5 10.4 32.1 21.7 23.6 100.1 106 Total 4. 1 9.0 13.9 27.7 27.0 18.4 100. 1 267 1 Material on the ulnar nerve is restricted to Army Registry cases within the sampling area, but for the median and radial nerves this restriction was not made here. 1 See table 63 for rubrics of classification. For describing the average recovery of lesions upon the major nerves use has also been made of the arithmetic averages of several performance characteristics of the individual muscles chosen as most representative for each nerve. Each nerve is represented by 3 or 4 such muscles as described 120

Table 70.—Modified British Classification of Motor Recovery Following Complete Suture, Multiple Lesions Only, by Nerve British motor classification No. of injured nerves, by nerve M U R P T SP No contraction 4 2 1 1 2 1 1 1 Perceptible contraction proximal only * 1 1 1 Proximal against gravity, perceptible contraction in intrinsics 3 4 1 1 1 Proximal and distal against resistance 1 As above, plus some synergic and isolated movements . . Total . . . . . . 1 8 12 3 1 2 2 Table 71.—Effect of Multiple Lesions Per Nerve on Motor Recovery, Lesions With at Least One Complete Suture, All Major Nerves Combined British motor classification Number of injured nerves Observed Expected At best perceptible contraction in proximal muscles 14 4.80 Proximal against gravity, no more than perceptible contraction in distal 7 11.15 Both proximal and distal against resistance ... . . 7 12.04 Total 28 27.99 in the footnote to table 72. Distal muscles are represented only for the upper extremity, the ulnar having 2, the median and radial 1 each, and on that account alone the averages of table 72 will seem an arbitrary basis for comparing the several nerves. However, such comparisions are of dubious meaning at best; one is primarily interested in the overall picture for a particular nerve, and for this purpose the device has whatever merit inheres in the selection of the muscles upon which it is based. In the first column of table 72 appears the average percentage of muscles exhibiting at least a perceptible contraction. It was obtained by averaging the separate three or four values for the particular muscles selected as representative, giving each such muscle equal weight. Other columns were obtained in a similar fashion. As in the tables on individual muscles two averages are given for relative power, one for all muscles regardless of their ability to contract and the other for only those muscles found capable of contracting against resistance. 408880—87- -10 111

Table 72.—Summary of Motor Recovery Based on Average Performance of Selected Muscles,1 by Nerve and Type of Operation Average percentage of muscles contracting Mean relative power Nerve and gross site Muscles contracting against resistance Total Against resistance All muscles Complete sutures Median, High 85 00 57 00 20 00 37 98 Low . . 89. 50 71 50 36 50 49 27 Total 86.50 61.70 25.98 41.99 Ulnar, High 85.66 50.80 15. 98 29.58 Low 90 76 57 62 21 48 53.83 Total 88 00 54 00 18 15 32 43 Radial 88.71 68 31 29.46 43.51 Peroneal 66.66 31.69 16.56 52.18 Tibial 75.69 51.95 25. 15 44.53 Sciatic-peroneal 48.23 14 47 3 69 36 49 Sciatic-tibial 50 05 33 24 17.40 42.23 1 Veurolyses Median High 91 47 80 71 48 87 59 76 96.67 65.57 44 64 69 03 Total 92. 10 79. 30 51.54 60.22 Ulnar, High. . 96 55 79 76 42 31 54 93 Low 89 63 78 02 36 36 48 01 Total 96.60 80.80 41.23 53 85 Radial 92.70 83.34 47.76 56.61 81. 15 63.25 33.03 51.66 Tibial 96.29 79.47 43.22 53.85 Sciatic-peroneal 88. 16 61.75 32.22 54.50 Sciatic-tibial 78.00 57.91 36.42 65.36 1 The muscles averaged are those described in the footnote to table 48, including the abductor pollicis brevis. 3. Summary All the motor indices employed here in describing motor recovery yield consistent results, but the observations made on individual muscles affected by representative lesions treated by suture or neurolysis have been most extensively studied. There is certainly a great deal of inherent variability in the material. Study of the individual muscles shows some concentration at 0 power, varying by muscle and by nerve, but otherwise a fairly uniform distribution of values over much of the range of relative power. Essentially 122

normal power, say 90 percent or more of that of the control limb, is rela- tively rare. There is considerable similarity in adjacent muscles innervated by the same nerve, but on the whole the proximal muscles make much the better return within any set specific to a single nerve, and there is great variation from one set to another and especially between those of the upper and those of the lower extremity. In addition, site of lesion is observed to exert a profound influence upon motor recovery following complete suture, distal lesions doing far better than proximal, especially from the standpoint of the more proximal muscles. Gross site of lesion has no apparent influence on motor recovery following neurolysis, however. Among upper extremity sutures the advantage of the more distal lesions is less a matter of the ability of muscles to contract than of actual strength of movement. Among sutures on lesions of the lower extremity the pattern is more complex: tibial lesions are favored over sciatic-tibial only as to the likelihood of contraction, not as to actual strength of any movement, while peroneal lesions recover better than sciatic-peroneal in both aspects. Recovery following complete suture is not reliably associated with the apparent character of the lesion. The same conclusion applies to neuroly- sis. Lysed, partially sutured, and completely sutured lesions recover in that order, the advantage of lysed lesions being quite large. The factor of age, in young men wounded in combat, would not be expected to exert any effect upon motor recovery and none was observed. D. INFLUENCE OF ASSOCIATED INJURIES, INFECTIONS, AND THERAPEUTIC PROCEDURES To explore the possible influence of associated injuries and complications, all roster and sampling restrictions were removed in favor of full utilization of all available case material. In most instances the exploration was con- fined to a study of the data on individual muscles, especially the smaller set described in table 48. The specific conditions which were explored for their effect on motor recovery are the following: Associated nerve injury. Bone and joint injury, and type of healing. Infection of sufficient degree to delay repair. Associated arterial injury. Plastic repair at site of nerve suture. It should be emphasized that it is the movement of individual muscles which is studied here, not motor function in the synergistic sense. For the most part these conditions were investigated only for complete sutures. Two of them, at least, namely, infection and bone injury, are confounded with time, in that presence of the condition tends to delay repair in any case, and some consideration must be given to untangling any effects which may be confounded in this way. 123

1. Associated Nerve Injury Because of the specificity of the tests of motor recovery, it was not antici- pated that associated nerve injuries would have any appreciable effect upon motor recovery and comparatively little study has been made of the problem. High median lesions, treated by complete suture, were sub- divided into those with and those without a complete suture on the ulnar, and although no consistent pattern of superiority was noted for the pure median lesions when all 5 muscles were studied, the advantage of the 2 distal muscles (opponens and abductor pollicis brevis) seems clear enough (table 73). Table 73.—Percentage of Affected Muscles Contracting and Mean Power Following Complete Suture of High Median Lesions, by Presence of Associated Ulnar Lesion Also Completely Sutured Present Complete ulnar suture Absent Median muscle Statistical tests1 Percent- age con- tracting against resistance Percent- age con- tracting Num- ber of cases Mean power, all cases Num- ber of cases against resistance Mean power, all cases A B 49 34 49 41 33 89 84 65 45 26 57.4 41.0 25.4 11.1 8.0 40 28 39 35 26 90 64 63 63 67 60.4 25.9 16.9 23.6 21.0 NS NS Fl poll. long NS NS NS NS Fl. prof. ind NS ** ** * 1 Two series of tests (one-tailed) were done, one on the percentage contracting against resistance (col. A), the other on mean power (col. B). Results of statistical tests are abbreviated as follows: NS=Not significant *=Significant at .05 level **=Significant at .01 level. A somewhat similar study was made of sciatic lesions, those with com- plete sutures on both sciatic components being contrasted with those in which only one component was completely sutured (table 74). In the sciatic-peroneal comparisons there is no suggestion that the complete sciatic lesions did not do as well as those requiring suture of the sciatic-peroneal component only. However, in the sciatic-tibial comparisons there is ade- quate evidence that, in the flexor digitorum longus and the flexor hallucis longus, complete sciatic lesions actually do less well than those requiring suture of the sciatic-tibial component only. The advantage of the incom- 124

plete lesions is not shown by the comparison of mean values for these muscles, but these tests are rather insensitive in this particular instance, and more reliance may be placed on the comparison of percentages con- tracting against resistance. Table 74.—Percentage of Affected Muscles Contracting Against Resistance and Mean Power Following Complete Suture, Complete and Incomplete Sciatic Lesions Compared Complete Incomplete Statistical tests' Muscle Percent- age con- tracting against resistance Percent- age con- tracting against resistance Num- ber of cases Mean power, all cases Num- ber of cases Mean power, all cases A B Peroneal Tib. ant ... 144 142 143 142 18.6 10.3 7.6 18.1 5.80 1.76 1.50 4.08 73 75 72 74 16.2 9.2 2.97 1.73 2.50 2.84 NS NS NS NS NS Ext. dig. long NS NS Ext. hall. long 9.6 14.5 Peron. long NS Tibial Oastroc. & sol 134 144 143 81.0 6.2 4.9 42.35 2.40 1.61 30 32 32 81.2 18.8 21.9 53.17 4.22 5.47 NS * NS NS NS Fl hall long ** 1 Two series of tests (one-tailed) were done, one on the percentage contracting against resistance (col. A), the other on mean power (col. B). Results of statistical tests are abbreviated as follows: NS=Not significant *=Significant at .05 level **=Significant at .01 level. 2. Associated Bone and Joint Injury Peripheral nerve injuries are commonly accompanied by injuries to bones and joints, and their management complicated thereby. As explained in chapter II, attention was paid not only to the presence of such associated injuries but also to their outcome, and both aspects are examined here. The investigation was done on the basis of individual muscles, both power and ability to contract being examined in detail. Neither aspect of motor recovery appears to have been influenced, in any general way, by the presence of such injuries or by the character of their healing. Table 75 summarizes the available data on presence of bone injury. In a few of the 125

Table 75.—Percentage of Affected Muscles Contracting and Mean Power Following Complete Suture, by Presence of Associated Bone and Joint Injury Nerve Muscle Absent Bone injury * Present Statis- tical tests' N % X N % X A B Median, high . . . Median, low. . . . Ulnar, high FL poll. long Fl. dig. prof. 2 Abd. poll. brev. . . . Fl. poll. long Fl. dig. prof. 2 .... Abd. poll. brev. . . . Fl. dig. prof. 4 & 5 . Abd. dig. V 80 116 75 16 22 41 160 184 134 46 115 87 80 78 78 70.8 63.1 41.3 76.5 79.2 55.1 30.88 21.72 12.73 49.06 53.86 18.29 29.16 5.57 7.50 39.13 11.00 10.52 43.94 31.99 18.91 17.45 8.77 7.01 17.39 50.67 6.00 6.28 5.23 2.38 1.98 4.66 45.52 3.02 2.62 18 60.0 57.6 27.3 69.0 85.7 46.2 16.11 18.17 6.67 35.74 47.16 12.03 31.29 8.94 8.35 38.56 13.20 13.88 35.66 20.48 15.37 15.74 9.84 8.71 18.19 67.67 12.29 11.14 4.54 1.06 2.09 2.25 42.72 1.67 1.27 NS NS NS NS NS 30 21 27 37 59 97 108 82 64 144 107 152 146 148 54 61 58 58 15 24 22 65 66 67 65 46 51 51 NS NS NS NS NS NS NS NS NS NS NS NS NS * ** NS NS NS NS NS NS NS NS NS NS NS NS NS NS NS Ulnar, low Radial Peroneal 1st dors. inteross. . . Fl. dig. prof. 4 & 5 . Abd. dig. V 32.4 37.8 NS 1st dors. inteross. . . Ext. car. rad Ext dig . ... 44.4 46.6 NS 87.0 70.8 58.0 81.2 54.6 46.8 NS * Ext. poll long .... NS Tib. ant ins Ext. dig. long Ext. hall. long. . . . Peron long 114 112 111 30 45 42.2 41.0 NS NS Tibial Gastroc. & sol. ... Fl. dig. long .... Fl. hall. long 47 16? 21.3 42.3 Sciatic-peroneal . Sciatic-tibia! Tib. ant Ext. dig. long Ext. hall. long. . . . Peron. long 162 159 162 124 151 20.7 9.0 5.9 • NS Gastroc. & sol. ... Fl. dig. long Fl hall long 130 8.4 1 Symbols used in headings are defined as follows: N=Number of injured nerves %= Percentage contracting against resistance X = Mcan relative power, all cases. > Results of statistical tests are abbreviated as follows: NS=Not significant *= Significant at .05 level **=Significant at .01 level. Probabilities were obtained as follows: A represents test of proportions with no con- traction, with contraction but not against resistance, and with contraction against resistance; B represents two-tailed test on means. 126

tests on the effect of the mere presence of such associated injuries, including those on two radial muscles, individually significant differences are noted, but too few to support the notion of any general effect. One could neither affirm nor deny an effect confined to the radial without paying more attention to specific site of injury, with which bone injury is confounded. Abnormal healing was so rare as to permit of investigation at only a few points, and these are given in detail in table 76. The data there provide no reason for believing that the character of healing exerted a real effect on motor recovery. 3. Chronic Infection Delaying Repair Although infection was not a frequent problem, it complicated the management of lesions on every nerve with sufficient frequency to permit a systematic study of the effect associated with it. Table 77 shows this effect to be a real one, especially in the upper extremity. Since in the ulnar the effect is seen only in the proportion making some contraction, however weak, the detail of the table extends to both the percentage making any movement and the percentage moving against resistance, and to both the mean power for all muscles and that for only those able to contract against resistance. As a rough measure of the magnitude of the effect one may take the difference between (or alternatively the ratio of) the two percentages contracting against resistance for any muscle. If these be averaged one finds that in lesions complicated by infection muscles contract against resistance only about two-thirds as often as muscles not so complicated. Table 76.—Percentage of Affected Muscles Contracting and Mean Power Following Complete Suture, by Type of Healing of Associated Bone and Joint Injury Nerve Muscle Normal ' Healing Other i Statis- tical tests ' N % X N % X A B Median Ulnar (high).. Radial Fl. poll. long Fl dig prof. 2 32 49 75.0 73.6 48.2 17 18 31 34 41 35 54 52 52 47.1 72.7 29.0 NS NS NS Abd. poll. brev 56 63 36.63 27.50 NS Fl. dig. prof. 4 & 5 . . Abd dig V .... 67 30.32 9.93 9.57 36.53 19.95 16.30 33.09 7.32 6.71 34.07 21.44 13.65 NS NS NS NS NS NS Ext. car. rad 47 98 94 96 18.2 85.0 52.0 49.0 10.3 74.1 59.3 42.6 * NS NS NS Ext. dig Ext. poll. long 1 The abbreviations used here are the same as those of table 75, and probabilities were obtained in the same way. 127

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Since the criterion of infection involves a delay in repair, and differences of considerable magnitude are observed in association with both infection and, as shown below, time itself, an effort was made to ascertain whether the apparent effect of infection could be explained on the basis of a delay in repair. The investigation was confined to three radial muscles and is summarized in table 78. Plainly most if not all of the discrepancy associ- ated with infection can be explained on the basis of delay in repair, and to the extent that the radial may be taken as representative it would appear that effect of infection is probably confined to the delay in repair it generally produces. In the radial this delay was appreciable; the average interval from injury to definitive suture is 151 days for lesions without infection and 386 for those with infection. The calculated values of table 78 are based on linear regression lines for power and day of operation, which for the radial seem technically satisfactory, and provide estimates of power for sutures done at day 386, which is the average for lesions with infection. Table 78.—Observed Average Power of Representative Radial Muscles Following Complete Suture, by Presence of Infection at Site of Lesion, and Calculated Power for Sutures Delayed to Same Extent as Lesions With Infection Observed mean power, by presence of infec- tion Calculated mean power, suture done at 386 days Radial muscle Absent Present Ext car. rad 40.38 26.12 18.08 18.75 6.84 1.75 20.5 10.2 7.2 Ext. dur. . * Ext poll long ... Mean day of repair 151 386 386 4. Associated Arterial Injury Among lesions in the upper extremity, and especially in high median injuries, associated arterial injury was common, but varying greatly by specific site of injury. For this reason alone peripheral nerve lesions will seem to be adversely affected by associated arterial injuries unless differences in site are taken into account. When site is controlled in some detail, as in table 79, the weight of the evidence seems to favor the view that an associated arterial lesion affects motor recovery adversely. Since there are only six independent sets of cases for specific sites, and recovery in one muscle is not independent of that in another in the same man, the aggregate amount of independent information is not large, but the observed discrep- ancies at the higher sites have a probability of less than .01. One might wish to discount evidence based solely upon differentials in relative power, on the ground that arterial injuries would often, and independently of any 1*0

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nerve injury, result in some loss of muscle power. However, the evidence in favor of an effect is not confined to relative power, but extends to both minimal contraction and contraction against resistance. Although one would perhaps not expect the effect of a delay in repair to be confounded with that of arterial injury, it is nevertheless of interest to note that time plays no part in producing these differentials. The mean day of definitive suture is as shown in table 80 for each nerve, in relation to arterial injury. There is even some suggestion that definitive sutures were done a little earlier on lesions with associated arterial injury. If the percentages con- tracting against resistance are employed in developing an estimate of the average magnitude of the effect of arterial injury, one finds that muscles affected by such injuries contract against resistance with only 82 percent of the frequency observed for muscles not so affected and of comparable site. Table 80.—Associated Arterial Injury and Average Days From Injury to Definitive Suture, by Nerve and Gross Site Mean day of repair Nerve and gross site Arterial injury absent Arterial injury present Median* high 154 184 150 170 139 Radial all 175 Since the evidence is clear that arterial injury plays a role in motor recovery, and that arterial injury is confounded with site, the effect of site upon motor recovery merits review on the basis of cases with no as- sociated arterial lesion. This may also be done from table 79, which parallels table 53 presented earlier in the discussion of the effect of specific site upon motor recovery. Very litde change is introduced by this refine- ment; muscles for which motor recovery varies by site in table 53 look about the same in table 79, largely because of the superior performance of low lesions. 5. Plastic Repair at Site of Nerve Suture Such repairs were abstracted from the clinical records, it may be recalled, whenever a definitive major plastic procedure had been done at the site of the nerve injury, regardless of indications, provided it was performed before regeneration of the nerve following definitive suture. Such repairs were not done often enough to permit any very powerful exploration of their effect, even in this large series. Only in median, ulnar, and peroneal lesions may they be studied fruitfully. In the peroneal their deleterious 134

effect seems plain enough; in the median and ulnar the evidence is less compelling, but somewhat in support of the conclusion that the effect is a general one. Table 81 contains the data studied in connection with this problem. The data are so few, and so variable by nerve and by muscle, that little purpose is served by an estimate of the average magnitude of the effect, and somewhat different results are obtained by different methods of estimation. However, it may be said that muscles affected by plastic repair contract against resistance about 80 percent as often as those not so affected. For low median and all peroneal lesions some exploration was made on the possible confounding of plastic repair with delay in nerve suture, but none was found. The differences in date of definitive suture are statistically insignificant and too small to produce large effects. 6. Summary In reviewing the records of the original injury and its management, the opportunity was taken to record those associated injuries and procedures which might influence nerve regeneration and muscle strength, and these have now been intensively studied for evidence of variation in capacity of muscles to contract and in their relative power. It should be emphasized that the study of associated injuries is here confined to their influence upon the strength of certain representative movements, and that a movement which is not possible because of defects in a joint, or destruction of muscle or tendon, is excluded from consideration. Associated nerve injuries have not been subjected to the intensive study accorded other associated conditions, but evidence from both upper and lower extremity lesions suggests that the recovery of one nerve is probably prejudiced by injury to another. Following high median suture recovery of distal muscles (opponens and abductor pollicis brevis) was definitely poorer in men who also had ulnar sutures on the same limb. No effect of associated sciatic-tibial sutures could be demonstrated for limbs with sciatic-peroneal sutures, but the recovery of tibial muscles was much poorer following suture of both sciatic branches than following suture of the sciatic-tibial alone. Associated bone and joint injuries were systematically investigated both as to presence and as to character of healing, but without developing statistically significant evidence of any influence upon motor recovery. Chronic infection was noted only if sufficiently prolonged to delay repair, and although statistically significant differences were found, suggesting an average loss of one-third in the expected percentage of muscles capable of contracting against resistance, an investigation on three radial muscles strongly suggests that most or all of this large effect may be explained solely on the basis of the delay in repair. Evidence is lacking, therefore, of any specific deleterious effect attributable to infection. 133

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Comcomitant arterial injuries appear to be associated with an average loss of about one-seventh in the expected percentage of muscles contracting against resistance, and no evidence was obtained that delay in definitive nerve suture plays any role in this relationship. In the peroneal, and to some extent also in the median and ulnar, a plastic procedure performed at the site of nerve injury prior to nerve regeneration was found to be associated with an average loss of about one-fifth in the expected percentage of muscles contracting against resist- ance. Any delay in definitive nerve suture associated with such plastic repair is of too little moment to play any role in this relationship. E. INFLUENCE OF TECHNICAL ASPECTS OF MANAGE- MENT Although the greatest immediate interest in a follow-up study on peripheral nerve injuries attaches to any conclusions which may be drawn in the area of management, it is precisely in this area that it is most difficult to draw clear and simple conclusions. The reason, of course, is that man- agement is not experimental but therapeutic in intent, so that the choice of procedures immediately becomes entangled with prognosis. Nevertheless, because of the great practical importance of information about the manage- ment of peripheral nerve injuries, because the difficulty is not peculiar to this series but extends to any not frankly experimental in nature, and because the present series is large enough to allow the use of statistical devices for coping with confounding where such seems indicated, the major characteristics of treatment have been studied systematically in the expecta- tion that useful, if not always unequivocal, conclusions might be forth- coming. For the most part, the elements of treatment have been studied individually, more than one being introduced only in connection with efforts to cope with serious confounding. A much more complex, multi- variate analysis might have been attempted, but its possible usefulness was suggested only late in the study when the funds for statistical work had been very largely expended, and the statistician believed that the additional information it would provide might well prove to be small. In the analysis of treatment factors the entire series was used, regardless of roster and sampling area. 1. Number of Operations Particular importance attaches to the definition of an "operation" em- ployed in this study, and the reader is referred to page 40 for a dis- cussion of the principles involved in the coding of operations. Not more than half of the definitive sutures with more than one operation had more than one suture; for each nerve usually half or more had a lysis before or after suture, or a so-called significant cuff removal. Since one would expect 138

lesions with more than one operation to have a poorer prognosis than those with a single, the data of table 82 offer no surprise, unless it be that the advantage enjoyed by lesions operated on but once is not larger. Without any estimate of how badly the cases reoperated upon would have fared had the second procedure not been done, there is lacking any statistical basis for assessing its benefit. There were 10 lesions with 4 operations each, and table 83 provides a summary of the sequence of operations in each instance and of such follow- up information as became available. Although few in number, these cases constitute strong evidence, if any were needed, that repeated suture need not be self-defeating; most of these had 3 complete sutures and some recov- ery was noted in 8 of the 9 with follow-up data. 2. Days from Injury to Definitive Repair Time intervening between injury and repair was studied more intensively than any other single characteristic, not only because of the importance accorded it in the surgical literature but also because it was found to be confounded with so many other factors in the study. In the previous section it was seen that associated injuries often greatly delay definitive repair, and it is to be expected that various aspects of management will change as time progresses without definitive repair. A circumstance which a priori would be expected to exert a great influence upon the relation between recovery and time to definitive repair is the fact that the lesion which was observed not to be doing well would often be resutured. Since resuture would necessarily take place at a later date, a connection would seem established between cases of poor prognosis and long interval, but the evidence of the present series is that any such connection may do no more than exaggerate slightly the intrinsic relation between time and motor recovery. The basic evidence of relationship between motor recovery and interval from injury to definitive operation appears in figure 12. The average relative strength of any muscle varies somewhat with timing of definitive repair in relation to date of injury. However, the association is not a very strong one and criteria of statistical significance are not always met by the data. Although Pearsonian (product-moment) correlation co- efficients were not routinely calculated, for 2 radial muscles they are shown in table 84, by site, for complete radial sutures. It is in the radial muscles that the correlation is most obvious, however, as may be seen from the correlation ratios 12 presented in table 85. Although the relationship is a quite definite one, therefore, it is variable from nerve to nerve and even within the set of muscles innervated by a particular nerve, and none too strong at best. 1J If the regression relationship between two variables is precisely linear, the cor- relation ratio and the Pearsonian (product-moment) correlation coefficient are the same. 13*

Table 82.—Mean Power of Affected Muscles After Complete Suture, by Number of Operations Performed Number of operations Statis- tical tests' Nerve, site* and muscle One Two or more Number of cases Mean power Number of cases Mean power High median Fl. poll. long 81 123 27.96 22.11 10.46 17 23 20 29.12 15.00 15.00 NS Fl. dig. prof. 2 NS NS Abd. poll. brev 76 Low median Abd poll brev 84 13.27 16 21.56 NS High ulnar Fl dig prof. 4 & 5 207 32.27 7.92 8.76 52 61 22.79 3.77 5.11 * * NS Abd. dig V. 233 174 44 Low ulnar Fl dig prof 4&5 92 203 154 39.82 13.14 12.82 18 57 41 33.61 9.21 10.61 NS Abd dig. V NS NS 1st dors inteross Radial Ext car. rad 192 189 192 38.70 26.19 17.08 40 35 34 37.63 15.29 14.12 NS Ext. dig NS Ext. poll. long * Peroneal Tib ant . 115 120 117 114 20.91 10.75 8.80 22.94 47 55 53 55 7.02 5.64 4.91 6.73 ** * Ext. dig. long Ext. hall. long NS ** Sciatic-peroneal Tib. ant 177 177 176 176 5.74 2.57 2.56 4.86 50 51 50 51 2.50 0 .10 .88 NS Ext dig long * * * Ext hall. long Peron. long Sciatic-tibial Gastroc & sol 135 143 142 47.37 2.69 2.50 35 39 39 34.71 2.44 1.28 * NS NS Fl. hall. long 1 Results of statistical tests are abbreviated as follows: NS=Not significant. *«= Significant at .05 level. **= Significant at .01 level. All tests here are one-tailed.

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12 (p. 3). Mean Relative Power in Relation to Interval From Injury to Definitive Suture, by Nerve and Muscle—Radial 100 200 300 400 500 600 700 800 DAYS FROM INJURY TO OPERATION 900 1000 The proportion of muscles capable of contraction was not studied as systematically as mean power, but table 86 contains the information which is available on certain median and ulnar muscles following definitive suture. Plainly the effect of time extends to both the likelihood of perceptible contraction and the likelihood of movement against resistance, but again, as in the observations on relative power, the effect is not seen either in all nerves or in all muscles, and tends to be especially marked in muscles innervated by the radial and the peroneal. Also, the effect often seems greatest in the most distal muscles. 144

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Table 84.—Correlation Coefficients Between Relative Power of Muscle Movement and Time From Injury to Definitive Suture, by Site, Two Radial Muscles Site of lesion in arm Correlation between rela- tive power and time from injury to definitive suture Ext. car. rad. Ext. dig. Upper third —.20 '—.30 Middle third '— .41 '— . 38 '—.36 '—.28 * Significant at .05 level. * Significant at .01 level. Table 85.—Correlation Ratios Between Relative Power and Days From Injury to Definitive Suture, by Nerve and by Muscle Nerve, site* and muscle Correlation ratio ' Nerve, site, and muscle Correlation ratio ' Median, high Fl. dig. prof. 2 Radial, all — Continued Ext. dig .304 .404 Abd. poll. brev .385 .335 Median* low Fl. poll. long Peroneal, all Tib. ant .401 .408 Ext. dig. long .407 Ulnar, low Ext. hall. long .300 .294 468 Radial, all Sciatic-tibial Gastroc. & sol .322 Ext. car. rad .422 1 Shown only for those muscles in which the ratio differs significantly (P<.05) from 0. The confounding of time and associated injuries has already been men- tioned. For 1 representative muscle innervated by each of 4 nerves a special study was made on the correlation of time and muscle power for cases with and without each of several associated conditions. In general, as may be seen from table 87, the (Pearsonian) correlation coefficient is the same, whether calculated for cases with or without each of the associated conditions. 147

Table 86.—Relation Between Interval From Injury to Definitive Suture and Capacity to Contract Affected Muscles, by Nerve and Muscle Num- ber of cases i Percentage contracting, by days from injury to final suture Percentage contracting against resistance, by days from injury to final suture Nerve, gross site, and muscle 1-99 100- 179 180 or more 1-99 100- 179 180 or more Median, low Opponens 160 114 93.7 88.9 83.9 83.1 76.3 65.6 66.7 51.6 55.4 Abd. poll. brev 87.5 62.5 44. 1 Ulnar, high Fl. dig. prof. 4&5 278 301 232 95.4 97.0 87.2 76.4 85.6 80.8 76.3 75.9 31.8 37.3 79.2 40.4 32.6 66.7 Abd. dig. V 87.5 82.1 31.7 38.2 Ulnar, low Abd. dig. V 265 205 92.2 91.7 91.8 89.3 88.3 79.3 46.9 50.0 44.0 41.7 43.8 40.2 1 The total number of tested muscles, and thus the sum of the bases for the several percentages for each muscle and not for any single percentage. On the premise that complete and incomplete lesions might differ con- siderably as to the extent of distal regeneration expected from lengthening the interval from injury to suture, several muscles were chosen for a special study of the role of type of lesion: Median: abductor poll iris brevis, for which a gross relationship with time seemed clear, especially in high lesions. Ulnar: abductor digiti V, for which no evidence of relationship had previously been found. Radial: extensor carpi radialis, extensor digitorum, and extensor pollicis longus, for each of which a quite marked correlation with time had been found. The investigation provided no reason for believing that type of lesion played any role in the relation between time and ultimate muscle power. Table 88 presents parallel mean values for complete and incomplete lesions, both completely sutured. Several aspects of the management of the lesion were considered from the standpoint of their possible effect on the relation between recovery and time to repair. The echelon of repair was one of these, since all overseas sutures were of necessity done early. Three representative muscles were studied in this connection: extensor carpi radialis, abductor pollicis brevis, and peroneus longus (for peroneal lesions only, i. c., those below 148

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Table 88.—Comparison of Mean Relative Muscle Power of Complete and Incomplete Lesions, Both Completely Sutured, by Interval From Injury to Definitive Suture, by Nerve and Muscle A. Radial Muscles Days from injury to definitive repair Ext. car. rad. Ext. dig. Ext. poll. long. Com- plete lesions Incom- plete Com- plete lesions Incom- plete lesions Com- plete lesions Incom- plete lesions lesions 0-99 52.4 38.1 26.9 56.4 42.2 37.0 36.9 28.0 13.8 43.2 25.6 15.3 21.7 20.1 9.3 32.8 13.9 100-139 1 40 or more 16.1 B. Ulnar, abd. dig. V C. Median, abd. poll. brev. Days from injury to definitive repair Com- plete Incom- plete lesions Days from injury to definitive repair Com- plete lesions Incom- plete lesions lesions 0-59 9.5 7.3 0-99 19.5 19.2 60-119 8.4 12.8 100-159 10.3 18.2 120-179 8.5 14.2 160-219 13.3 14.7 1 80-239 9 1 12 0 5.6 12 0 240 or more ... 7.4 10.0 the branching of the sciatic). When overseas sutures were removed from the series the association between time and muscle recovery remained unchanged. Table 89 contains the data underlying this conclusion. Another aspect of treatment thought to introduce some bias into the data has already been mentioned, namely the fact that the date of definitive repair was necessarily advanced for cases requiring reoperalion. Accord- ingly, a study was made on the basis of time to first suture, but again the relationship to time appears in full force. In part this is because so many resutures were actually done fairly early in the Z/I following suture over- seas. Table 90 presents the relation between motor recovery and time to first suture, in terms of capacity to contract against resistance as well as mean power of all muscles, whether contracting against resistance or not. Since, as will be shown later, both the interval from injury to suture and the surgical gap are quite reliably associated with ultimate muscle power, both factors were explored simultaneously on the basis of the extensor carpi radialis and the extensor digitorum, with attention to the site of injury. For time and gap themselves the Pearsonian correlation coefficients are all significant at the .01 level:

Table 89.—Percentage of Affected Muscles Contracting Against Resistance, Follow- ing Complete Suture in £//, by Time From Injury to Definitive Suture Nerve and muscle Percentage contracting* by days from injury to suture 0-99 100- 139 140- 179 180- 259 260 or more Median Abd poll brev . ... 47.1 92.3 66.7 39.1 36.4 82.4 35.3 23.5 80.9 36.1 18.2 56.8 13.0 Radial Pcroneal Ext. car. rad Peron. long 86.2 53.6 Table 90.—Percentage of Affected Muscles Contracting and Mean Power Following Complete Suture, by Time From Injury to First Complete Suture Days from injury to suture Num- ber of cases Percent- age con- tracting against resistance Mean relative power* all cases Nerve Site Muscle Median High. . . Fl. poll. long. . . . 1-99 34 82.4 38.4 100-179 49 67.3 26.6 180-279 17 47.1 20.6 280 or more 9 66.7 16.2 Fl. dig. prof. 2 . . 1-99 100-179 50 68 76.0 52.9 26.77 16.77 180-279 22 54.5 23.81 >280 15 66.7 15.83 Abd. poll. brev. . 1-99 100-179 35 42 51.4 38.1 17.80 8.68 180-279 16 25.0 8.13 >280 9 11.1 5.00 Low. . . Fl. poll. long. . . . 1-99 100-179 9 11 77. 8 90.9 43.13 59.50 180-279 16 68.8 37.33 >280 9 44.4 21.67 Fl. dig. prof. 2 . . 1-99 100-179 13 92.3 50.00 53.13 17 88.2 180-279 24 79.2 46.82 >280 11 72.7 44.44 Abd. poll. brev. . 1-99 100-179 28 29 64.3 18.25 17.86 51.7 180-279 30 40.0 15.56 Ulnar High... Fl. dig. prof. 4 >280 1-99 26 104 42.3 73.1 6.04 23.57 &5. 100-179 95 80.0 37.96 180-279 52 69.2 31.90 >280 27 66.7 23.80 131

Table 90.—Percentage of Affected Muscles Contracting and Mean Power Following Complete Suture, by Time From Injury to First Complete Suture—Continued Days from injury to suture Num- ber of cases Percent- age con- tracting against resistance Mean relative power* all cases Nerve Site Muscle Ulnar High. . Abd dig V 1-99 106 28.3 5.73 100-179 102 42.2 8.93 180-279 60 33.3 7.17 >280 33 36.4 5.45 1st dors. inteross. 1-99 80 36.3 8.66 100-179 83 31.3 7.93 180-279 44 43.2 9.76 >280 25 36.0 3.54 Ulnar Low . . . Fl. dig. prof. 4 1-99 35 77. 1 38.86 & 5. 100-179 42 78.6 41.10 180-279 27 85.2 37.09 >280 11 81.8 37.00 Abd. dig. V 1-99 73 45.2 11. 16 100-179 98 49.0 13.21 180-279 67 47.8 13.02 >280 27 33.3 10.58 1st dors. inteross. 1-99 55 41.8 13.49 100-179 75 42.7 11.99 180-279 56 51.8 15.00 >280 19 15.8 3.68 Radial All. .. . Ext. car. rad .... 1-99 83 95.2 52.46 100-179 93 83.9 36.80 180-279 51 78.4 30.22 >280 28 53.6 18.33 Ext. dig . . . 1-99 79 77.2 37.28 100-179 90 63.3 23.71 180-279 45 40.0 13.56 >280 24 29.2 9.13 Ext. poll. long. . . 1-99 78 64.1 23.77 100-179 90 60.0 16.76 180-279 46 30.4 9.67 >280 25 20.0 6.25 Peroneal All Tib. ant 1-99 59 49.2 25.95 100-179 50 34.0 13.40 180-279 42 28.6 12.50 >280 15 20.0 2.69 Ext. dig. long. . . 1-99 60 45.0 17.89 100-179 56 25.0 5.71 180-279 46 19.6 5.22 >280 17 5.9 1.18 Ext. hail. long... 1-99 59 35.6 13.2i 100-179 54 16.7 3.1i 180-279 45 17.8 7.78 >280 17 5.9 2.06 Pcron. long. . . . . 1-99 61 57.4 30. 34 152

Table 90.—Percentage of Affected Muscles Contracting and Mean Power Following Complete Suture, by Time From Injury to First Complete Suture—Continued Days from injury to suture Num- ber of cases Percent- age con- tracting against resistance Mean relative power* all cases Nerve Site Muscle Peroneal All Peron. long. . . . 100-179 54 37.0 11.04 180-279 45 33.3 13.26 >280 17 23.5 4.67 Tibial All Gastroc. & sol ... 1-99 18 88. 9 59 44 100-179 16 93.8 55.33 180-279 10 80.0 47.22 >280 4 100.0 70.00 Fl. dig. long. . . . 1-99 21 19.0 5.24 100-179 25 32.0 6.88 180-279 17 23.5 12.94 >280 11 54.5 10.00 Fl. hall. long. . . . 1-99 20 20.0 5.75 100-179 26 38.5 10.21 180-279 17 23.5 9.69 >280 10 30.0 2.78 Sciatic-pero- All Tib. ant 1-99 71 19.7 5.23 neal. 100-179 92 19.6 5.61 180-279 40 15.0 5.13 >280 26 19.2 2.31 Ext. dig. long. . . 1-99 71 14.1 3.24 100-179 94 12.8 2.06 180-279 40 5.0 .88 >280 27 3.7 .19 Ext. hall. long. . . 1-99 68 13.2 3.60 100-179 93 9.7 1.87 180-279 40 5.0 1.00 >280 27 0 0 Peron. long 1-99 72 22. 2 5. 21 100-179 92 16.3 3.65 180-279 40 17.5 4.50 >280 27 7.4 .93 Sciatic-tibial . . All Gastroc. & sol... 1-99 58 82.8 48.06 100-179 80 85.0 51.07 180-279 33 72.7 33.17 >280 17 70.6 26.00 Fl. dig. long .... 1-99 58 12.1 3.53 100-179 78 6.4 1.88 180-279 32 6.3 2.97 >280 17 5.9 2.06 Fl. hall. long 1-99 57 10.5 3.51 100-179 78 9.0 2.01 180-279 32 3.1 1.56 >280 17 0 0 403930—07- -12 153

Correlation between Site of radial lesion time and gap Upper third, arm +.70 Middle third, arm + .27 Lower third* arm +. 54 If the influence of gap is removed by the method of partial correlation no great change is observed in the correlation between time and power, as may be seen in the parallelism between the two sets of coefficients in table 91. The correlations between time and gap and between gap and power are not high enough to exert any great influence upon the relationship between time and power which remains the most important relationship of the three. Table 91.—Correlation Between Relative Power and Time From Injury to Definitive Suture, Directly and With Influence of Gap Removed, Two Radial Muscles, by Site Correlation coefficients for time and relative power Radial muscle and lite of lesion Directly Influence of gap removed Ext. car. rad. -.20 -.41 -.36 -.10 -.36 -.38 Lower third arm Ext. digitorum Upper third, arm ... -.30 -.38 -.28 -.15 -.35 -.30 VfirMlf third, arm Lower third, arm Estimation of the average magnitude of the effect of delayed repair will depend in part upon whether one believes the effect to be the same for all nerves and which index of motor recovery is employed. To portray an average line of relationship for each nerve, and for all nerves combined, figure 13 has been prepared, for lesions sutured only once, by expressing the average strength of any set of cases located on the time scale as a percentage of the average for all cases, regardless of date of repair of the particular lesion. It seems plain that the relationship is linear and that the best time to repair in general is the earliest time feasible. Figure 13 suggests, for example, that muscles innervated by nerves sutured in the interval from 280-399 days after injury will have about half the power observed for muscles innervated by nerves sutured within the first 100 days. If optimum power is taken as 100 percent for immediate sutures, then on the average 154

there is a loss of 1 percent about every 6 days. Alternatively, one may take the linear regression equations fitted to the data on several radial muscles, which yield about the same results. These equations are, where Y denotes relative power and X number of days from injury to suture: Figure 13. Average Relative Muscle Power in Relation to Time From Injury to First Suture, by Nerve PERCENT OF NORMAL POWER HIGH MEDIAN 150 - .t fc;„.;.„ :.i i t . f L SCIATIC PEKOHEAL SCIATIC TIBIAL UDIAL LOW MEDIAN LOW ULNAR TIBIAL ALL NERVES PERCENT OF NORMAL POWER 1200 150 100 150 100 100 100 11 1 1 t 1 100 200 300 400 5OO 600 0 100 200 3OO 400 SOO 6OO 700 DAYS FROM INJURY TO FIRST SUTURE 1S5

Ext. car. rad Y=51.40-.0800X Ext. dig Y=34.62-.0632X Ext. poll. long Y=23.07-.0412X Since the optimum power is indicated by the intercept value in each case, the relative losses at the end of 100 days are 16, 18, and 18 percent for the 3 muscles in turn, which is very close to the value of about 17 percent obtained by rough graphic interpolation from figure 13, panel for all nerves combined. It must be emphasized, however, that any such average con- ceals the variation among muscles, and particularly the fact that the effect tends to be strong in those innervated by the radial and peroneal, and weak or even absent in the ulnar and tibial muscles. Alternatively, if one con- siders as the index of motor recovery the percentage of muscles capable of movement against resistance, the effect is fairly similar. A comparison appears in table 92 for all nerves combined. Table 92.—Average Motor Recovery and Time From Injury to First Suture, for Two Indices of Motor Recovery, All Nerves Combined Relative motor recovery Days from injury to first suture Average strength of all muscles Average percentage contracting against resistance 1-99 100 84 74 51 43 100 94 76 73 34 100-179 180-279 280-399 400 or more A surgical qualification is needed to balance the foregoing statistical analysis which ignores the important fact, established in chapter II, that about half of the very early or emergency sutures required resuture. Also, the emergency sutures per se were not isolated for separate study and presentation in the foregoing analyses, but grouped with other early sutures. Accordingly, a supplementary analysis was made in which first sutures done on days 1 to 19 were compared, as to follow-up status, with first sutures done on days 20 to 49 and it was found that these earliest or emergency sutures, after such subsequent resuture as was required, actually did as well as other sutures done early but not so immediately. The disadvantage of the emergency suture, therefore, does not extend to follow-up status, having been mediated by resuture. On the other hand, a resuture rate of 50 156

percent is intolerably high. Also, it appears from the analysis of the emergency sutures that, in these instances at least, the value of resuture has been clearly established. 3. Calendar Date of Definitive Suture To mobilize surgeons in time of war is a tremendous task and the expec- tation is that satisfactory administrative and technical arrangements may not exist at the outset. It is of some interest, therefore, to observe in the material on motor recovery no evidence that definitive sutures done at one calendar time were any more or less successful than those done at another. 4. Echelon of Definitive Repair Although the great bulk of the sutures were done in Z/I general hospitals, a special effort was made to include early, overseas sutures for comparative purposes. As table 93 clearly shows, the definitive sutures done overseas are accompanied by much better results at follow-up, on the average, than was obtained with Z/I sutures. There are two artifacts which rob these data of any meaning for surgical policy: (a) the overseas sutures were early; and (b) those overseas sutures which remain as the definitive sutures were in men whose clinical progress was satisfactory and considered not to war- rant resuture. It was noted in chapter II that the resuture rate was con- siderably higher for first sutures done overseas than for those first done in the Z/I. When the follow-up data were compared on the basis of definitive first sutures only, to counteract the second source of bias, the advantage possessed by the overseas cases was found to be only slightly lessened. The factor of time was approached by matching Z/I and overseas cases as to day of surgery, and although early Z/I sutures were not common enough to make this approach a powerful one, it did yield remarkably identical results for the three muscles studied. Table 94 summarizes the data thus obtained, which are confined to contraction against resistance. The great difference in time of repair seems responsible, therefore, for the apparent discrepancy between definitive sutures done in the Z/I and those done overseas. 5. Length of Surgical Gap As already noted, surgical gap is only weakly correlated with strength of muscle power at follow-up, although moderately correlated with time from injury to definitive repair. That is, although on the average the very long gaps are associated with markedly less motor recovery, there is so much inherent variation that knowledge of gap is of no great prognostic value in the individual case. Figures 14 and 15 depict the average relationship observed for each nerve, the first on the basis of mean relative power of all muscles and the second on the basis of the percentage of muscles contracting against resistance. The ronstructinn nf figure 14 is exactly like that of 157

Table 93.—Mean Relative Power of Affected Muscles Following Definitive Suture Overseas and in the Overseas sutures Z/I sutures Statis- tical tests i Nerve, gross site, and muscle Number of cases Mean power Number of cases Mean power Median . All Fl. poll. long 17 19 18 42 46 34 18 37 26 38 37 40 29 29 29 29 35 35 34 36 30 32 32 40.88 31.84 26.67 27.38 6.74 8.24 38.33 12.70 18.08 58. 16 36.89 25.00 33.97 20.17 12.24 38.10 6.86 4.29 6.62 6.67 49.33 4.06 3.91 126 31.47 19.37 11.81 30.94 7.12 7.99 38.89 12.20 11.48 34.66 22.03 14.84 13.23 6.95 6.63 13.43 4.75 1.58 1.20 3.46 43.86 2.33 1.88 NS High Fl dig prof 2 127 180 217 248 184 92 223 169 194 187 186 133 146 141 140 192 193 192 191 140 150 149 * ** NS NS NS NS NS All Abd poll brev Ulnar High Fl. dig. prof. 4 & 5 . . High Abd. dig. V High 1st dors. inteross. . . . Low Fl. dig. prof. 4 & 5 . . Low Abd dig V Low 1st dors. inteross. . . . Radial All Ext. car. rad NS ** All Ext. dig *- * t* »* All Ext. poll. long Peroneal All Tib ant All Ext dig long All Ext hall long .... NS ** All Peron. long Sciatic -pero- All Tib ant NS NS All Ext hall. long ** All Peron long NS NS NS NS Sciatic-tibial All Gastroc. & sol All Fl. dig. long All Fl. hall. long 1 Results of statistical tests are abbreviated as follows: NS=Not significant *=Significant at .05 level **=Significant at .01 level. Table 94.—Comparison of Overseas and £/I Definitive Sutures Matched as to Time From Injury to Repair, as to Number of Affected Muscles Moving Against Re- sistance Overseas sutures Z/I sutures Nerve and muscle Number moving against resistance Number moving against resistance Number of cases Number of cases Median: Abd. p Radial: Ext. car Peroneal: Peron Total 14 19 29 62 8 19 18 19 33 70 8 18 23 49 rad 20 47 1M

figure 13, explained on page 154. Figure 15 is only roughly parallel, each plotting point for a particular nerve having been obtained by averaging directly the several percentages contracting against resistance observed for the individual muscles involved. The average for all nerves was then obtained from the averages for each nerve by weighting the latter by the number of lesions studied. Both figures tell about the same story for all nerves combined: In terms of both mean power and percentage contracting against resistance there is a loss of about 6 percent per cm., where 100 percent is the value (either mean strength or percentage contracting against resistance) for gaps under 1 cm. It must be emphasized, however, that in these data the apparent sensitivity of power to differences in length of gap varies by nerve, and that it may well be that no average picture fairly represents them all. Finally, it must be borne in mind that the data are clinical, not experimental, in nature. The surgeon sought to resect enough tissue to obtain good nerve ends, and yet not so much as to interfere with approximation or to incur an undue risk of disruption. The longer gaps, in general, are associated with more extensive wounds involving other tissue; shorter gaps may arise in part from excessive caution on the part of the surgeon. For these reasons the clinical observations do not lead so surely to definite conclusions as would experimental observations, in which length of gap could be randomly assigned. 6. Transposition or Extensive Mobilization as Special Operative Features The possible influence of transposition and extensive mobilization was systematically explored along the lines of table 95, without finding evidence of any general effect common to all nerves. Any suggestion of an effect is confined to the peroneal and sciatic-peroneal. The study was repeated with a limitation to lesions sutured only once, in order to guard against the possibility that the deleterious effects of transposition and extensive mobilization were lost sight of through the fact that their definitive sutures were second sutures, but no statistical evidence of heterogeneity was ob- served even with this refinement. It does seem well established, then, that these two special operative features have no demonstrably adverse influence upon motor recovery. 159

Figure 14. Average Relative Muscle Power in Relation to Length of Surgical Gap at Definitive Suture, by Nerve POWER pa (El MEDIAN 1.6 1.2 .8 ULJA8 1-6. 1.2 .8 [.I L_ 1 .2 .8 .4 .4 .4 0 •V 1 i \ 1: 1 1 III :,,, :: I L:': 0 0 1 2 3 X E 6789 10 01234567 \ 9 1 a NK I POI (ER 1.6 1.6 RADIAL 1.6 1.2 .8 .4 PERONEAL 1.2 IP""-" ' t I 1 " 1.2 .8 .4 ~~l~~ ..8 .4 O 0 1 i . 1 ., i j 1 1 t. J; 0 1 2 R 5456789 10 01234567! 1 9 1 a POK 1.6 ra «ER SCIATIC- PERODEAL TISIAL 1.2 .8 .4 0 1.2 F^^ 1.2 r .8 .4 ;::; - r^— .8 .4 ? 1 1 ..:.* 1 t £1r t L• 1 1 1 t-t. J •••! 01 234567891 R : 0 ( ) 1 234567 ..;. 0 ) 9 1 POt 0 POWE 1.6 IER SCIATIC- Z™J 1.6 nALL IIERVES 1.6 1.2 .8 .4 0 TIBIAL 1.2 .8 .4 0 1 1 1.2 .8 , . J r-r J V:i ; 1 n -C i r .4 O & J:J: . \ .:. T :?> I.. 1 234567 GAP* In cm 9 10 01234567 GAP* In a 9 1O 160

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7. Bone Resection It is not often that the surgeon finds it necessary to resect normal bone in the interests of achieving a more satisfactory anastomosis; in this series such resection was undertaken on 9 limbs involving 13 complete sutures as follows: median (4), ulnar (3), radial (6). The surgical gaps were not always long, ranging from 3 to 14 cm. and averaging 6.4 cm. Follow-up examinations were performed on 5 of the men and for 7 sutured nerve lesions motor recovery was classified according to the modified British code as follows: Modified British classification Number of lesions 0 No contraction at all None 1 Return of perceptible contraction, proximal muscles only None 2 Proximal muscles acting against gravity, no return of power in in- None trinsics. 3 Proximal muscles acting against gravity, perceptible contraction in Median (1) intrinsic muscles. Ulnar (2) Radial (2) 4 Retuin of function in both proximal and distal muscles of such an Radial (2) extent that all important muscles are of sufficient power to act against resistance. 5 Return of function as in category 4, with the addition that some None synergic and isolated movements are possible. 6 Complete recovery None Although the sample is pitifully small, it suggests that peripheral nerve regeneration in such cases is no different from recovery generally following nerve suture. 8. Bulb Suture The analysis of bulb sutures was made on the basis of both the definitive suture and the first suture, but there is very little difference between them since first sutures following bulb suture were rarely reoperated upon. There is not a great deal of information on bulb sutures, but such material as the series provides indicates that these cases did much less well than those not handled in this way. A summary of these data appears in table 96 for definitive sutures. It must be observed, however, that bulb suture is a staged procedure ordinarily reserved for long gaps, and that the evidence of this series is that gap per se is a factor to be reckoned with. Accordingly, the bulb sutures have also been compared with other sutures on gaps of similar length 13 and found not to differ appreciably, as may be seen from table 97. In short, preliminary bulb suture cannot be shown to have exercised any deleterious effect upon ultimate muscle recovery in this series. " An indirect procedure underlies this comparison. The estimates for cases in which bulb suture was not done were obtained as follows: Trend-lines were fitted by inspection to the individual panels of figure 14* for gaps of 0 to 8 cm., and extended to 10 cm., at which point the value of the trend-line was taken as the estimate of power for cases without bulb suture. 166

9. Character of Nerve Ends at Definitive Suture Operation reports did not always describe the gross appearance of the nerve ends which, after freshening, were ultimately approximated in the definitive suture; about a third of the sutures could not be satisfactorily coded in this respect. Although proximal and distal ends were assessed separately, it was rare for a surgeon to describe the ends as other than good or excellent, so that the only feasible analysis consists of pitting cases with both ends described as good against those with one or both ends described as only fair or even poor. Table 98 presents the data thus obtained, and makes it tolerably clear that the surgeon's description of nerve ends is of only limited prognostic value. Lesions in which the anastomosed ends were described as good or excellent appear to advantage in by no means every comparison, but do predominate with sufficient frequency to leave little doubt about their general superiority. On the average in cases with one nerve end described as only fair or even poor the tested muscles failed to contract perceptibly with 1.37 times the frequency observed for those in which both ends were described as good. They contracted against resistance about .85 times as often, and their average power (whether contracting against resistance or not) was about .79 times as much. Table 97.—Definitive Sutures With and Without Prior Bulb Suture, and Average Percentage of Affected Muscles Contracting Against Resistance, by Nerve Average percentage of affected muscles contracting against resistance Nerve sutured Bulb suture No bulb suture High median 59 37 46 0 8 22 40 35 45 15 5 25 Radial Peroneal Sciatic-peroneal Sciatic-tibial 167

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It is of interest to note here that there is some correlation between the surgeon's gross evaluation of nerve ends and that based on later histo- pathological study of the same cases by Dr. William R. Lyons. (See ch. XI.) For the 152 cases with both ratings, regardless of nerve involved, the relationship is shown in table 99. Table 99.—Relation Between Surgeon's Description of Nerve Ends Sutured at Defini- tive Operation and Neuropathologist's Average Rating as to Expected Recovery l Number of cases Neuropath- ologist's aver- age rating Surgeon's description of nerve ends 84 54 Both fair 49 43 Both poor 11 26 Mixed 8 48 Total 152 48 1 On a scale of 0 to 100; sec pp. 512-513 for complete description. 10. Tension Upon Suture Line The operator reported his impression of the tension on the suture line even less often than he described the nerve ends; 46 percent of the definitive sutures could not be coded adequately for this characteristic. In all but 21 percent of the sutures which were adequately described the operator observed tension to be essentially absent or slight, and in such instances the code rubric "no tension" was employed. However, the failure of the operator to note significant tension with any real frequency does create difficulties in studying the significance of his characterization of degrees of tension, and the main analysis here, as reported in table 100, consists of comparisons of sutures described as having at least moderate tension v. those with less than moderate tension. Although the data are not without some evidence that sutures under at least moderate tension did less well, especially those on radial lesions, if one insists that any effect be general, applying to all nerves, then the evidence is seen to be insufficient. For the numbers of lesions involved the differences are too small, and their direction too often contrary to expectation, to permit the conclusion that the opera- tor's report of tension is of real value in prognosis. The comparatively few lesions described by surgeons as characterized by severe tension were also studied separately but without adding appreciably to the evidence of association with follow-up status. It would appear, then, from these data and those of chapter II that the prognostic value of the surgeon's report of tension on the suture line is limited to the likelihood of resuture. 170

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11. Suture Material Although the great majority of World War II sutures were accomplished with tantalum wire, perhaps a fourth were performed with silk and in the sampling plan for this study a special effort was made to include cases from Dr. Thomas I. Hoen's plasma glue series. There are two comparisons of intrinsic interest, then—tantalum v. silk and tantalum v. plasma glue. Since the choice of suture material was made by the individual surgeon, there is no reason to expect that tantalum and silk sutures would differ in any important particular associated with prognosis, e. g., length of gap, etc., but no study has actually been made on this point, and to that extent their comparability is merely assumed here. The only factor which seemed worthy of scrutiny was echelon of definitive suture, but since 73 percent of overseas sutures and 70 percent of Z/I sutures were accomplished with tantalum, it was concluded that there was no confounding of suture ma- terial and echelon. Tantalum and silk sutures were compared directly, muscle by muscle, but only small and statistically insignificant differences were found. Table 101 presents these comparisons in detail. Special attention was, however, paid to the plasma glue series since it did not constitute an organic part of the Army Peripheral Nerve Registry but represented the work of a single surgeon at a particular Navy hospital (St. Albans) in the Z/I, and despite the fact, already described, that it represented consecutive, unselected cases seen at that hospital. The com- parison of tantalum and plasma glue sutures was made on the basis of the following characteristics, separately by nerve and, for median and ulnar lesions, by gross site: Associated nerve injury. Handedness. Type of injury to nerve. Specific site. Associated bone and joint injury. Chronic infection delaying repair. Associated vascular injury. Plastic repair at site of nerve suture. Number of operations. Days from injury to definitive repair. Length of surgical defect. Condition of nerve ends. Special operative features, e. g., bulb suture, transposition, and mobilization. Reason for any resuture. Reason for any obvious failure of suture. On all of these characteristics except three the tantalum and plasma glue cases are indistinguishable—specific site of lesion, number of operations, and days from injury to definitive repair. For sutures on the median and ulnar, but not for those on the other nerves, the lesions sutured by plasma glue were more distal than those sutured by tantalum. Low median and low ulnar sutures done by plasma glue were usually in the lower third of 174

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the forearm or in the wrist, while those done by tantalum were more often in^the upper and middle thirds of the forearm. Insofar as this confounding of site and suture material would be expected to bias the suture compari- sons, the bias would favor the plasma glue cases, since the more distal lesions do as well as or better than those proximal to them in the median and ulnar, but the magnitude of any bias could hardly be appreciable. The heterogeneity as to number of operations is somewhat more serious. The observations appear in table 102. Since not all operations were sutures, the discrepancy was explored further to ascertain if the plasma glue sutures more often required resuture, but such is not the case: they had more often been operated upon previously. Finally, the mean interval from injury to operation was found to be much greater for plasma glue cases (table 103). Table 102.—Percentage of Definitive Sutures With More Than One Operation, by Type of Suture Material, and by Nerve and Gross Site Percentage than one with more operation Nerve and gross site Tantalum Plasma glue Low median 16 45 Low ulnar 20 29 Radial 17 19 Sciatic . . 19 38 Table 103.—Mean Days From Injury to Definitive Suture, by Type of Suture Material, and by Nerve and Site Nerve and gross site Mean interval, in days Tantalum Plasma glue Low median 216 270 Low ulnar . 179 218 Radial, all 148 390 Sciatic, all 174 286 Tantalum and plasma glue sutures were first compared directly and, as would be expected from the differences already noted in number of opera- tions and interval from injury to operation, large and statistically quite significant differences were found. However, the results of these biased comparisons are not shown, but in their stead table 104 presents the best unbiased comparisons which could be developed from the present series. The latter selection was based on suture material at the first suture, to 17*

obviate the bias associated with the fact that so many of the St. Albans cases had previously been operated upon before the plasma glue sutures were performed, and the series were roughly matched for interval from injury to first suture because lesions in the St. Alban's series were operated upon somewhat later than those in the silk and tantalum series. These restrictions reduced the available plasma glue series to about 50 cases, 20 low median, 20 low ulnar, and 12 radial sutures. In table 104 these are contrasted with comparable silk and tantalum sutures on the basis of the voluntary con- traction of representative muscles; any doubt as to their homogeneity is dissipated by these data. If suitable care is taken to insure comparability of material, therefore, there is no reason to believe that motor regeneration following plasma glue suture differs in any way from that following suture with silk or tantalum. Table 104.—Voluntary Contraction of Representative Affected Muscles Following Complete Suture, by Nerve and Type of Suture Material Voluntary contraction Silk and tantalum Number Percent Plasma glue Number Percent Low median None 15 18.8 Perceptible or against gravity, but not against resistance 24 30.0 Against resisrance 41 51.2 Total 80 100.0 Low ulnar None 19 8.8 Perceptible or against gravity, but not against resistance 98 45. 1 Against resistance 100 46.0 Total 217 99.9 Radial None 9 6.3 Perceptible or against gravity, but not against resistance 15 10.5 Against resistance 119 83.2 Total.. 143 700.0 7 10 20 75.0 35.0 50.0 700.0 20 20.0 45.0 35.0 100.0 1 10 12 8.3 8.3 83.3 99.9 179

12. Use of Cuff About one-third of the definitive sutures were accomplished with the aid of a cuff, almost always one of tantalum foil. Also, about 1 out of 4 cuffs was removed some time after it had been placed. The observations permit, then, the exploration of two problems: (a) differences associated with the original decision to employ a cuff; and (b) differences associated with the subsequent decision to remove one already placed. These prob- lems were first studied grossly on the material as a whole, without regard for the possibility that cuffs might be used more on one type of case than another. Table 105 contains all the pertinent data for the first problem, and very strongly suggests that cases with tantalum foil generally had a somewhat better recovery than lesions not so treated. On the average, both mean relative power and percentage of muscles contracting against resistance were about 20 to 25 percent higher when tantalum cuff had been used. Surgical experience in the Z/I suggested that the decision not to employ a cuff might often be based on considerations which were unfavorable to regeneration. Examples are: (a) the presence of a large discrepancy in the size of a still partially scarred proximal end and an atrophied distal end in a late repair; (b) rerouting of the nerve might force location of the suture-line directly beneath the skin where the use of a cuff would be inadvisable; and (c) in a badly scarred area it might be thought that a foreign body might not be well tolerated. For these reasons a better controlled comparison of lesions with and without cuff was made on the basis of only those sutures which met the following specifications: Army Registry cases only. Absence of chronic infection delaying repair and of associated injuries involving bone, joint, or artery, or requiring plastic repair. Surgical gap of 6 cm. or less. Suture in the interval 40 to 199 days after injury. Among lesions meeting these specifications those in which a cuff was placed at definitive suture had no real advantage, as may be seen in table 106. The selection of cases to receive tantalum cuffs was also investigated in relation to the presence or absence of the associated injuries listed above, whether gap was more or less than 6 cm., and whether suture was done in the interval 40-199 days or later. It was found that the likelihood that a cuff would be placed at definitive suture varied quite markedly among the eight groups representing all the combinations of these factors, the influence of time being paramount. In figure 16 a comparison is made between the group of cases having the least favorable combination of these factors (one or more associated injuries, long gap, delayed suture) and the group having the most favorable (no associated injuries, short gap, and relatively early suture). The discrepancy between them as to percentage witli cuff is marked for every nerve. It does appear, therefore, that lesions with cuffs in this series generally have a more favorable initial prognosis. lao

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Figure 16. Percentage of Definitive Sutures Completed With Aid of Tantalum Cuff, Two Prognostic Groups From Army Registry NERVE MEDIAN: HIGH MEDIAN: LOW RADIAL ULNAR PERONEAL SCIATIC- PERONEAL TIBIAL SCIATIC- TIBIAL PERCENTAGE WITH CUFF 0 10 20 30 40 50 60 70 90 100 I I '///////////////////////////////A /////////////////////A —LEAST FAVORABLE PROGNOSIS ;/J-<MOST FAVORABLE PROGNOSIS y////////////////. The fact of selection, coupled with the failure of cases with cuffs to appear at an advantage when the comparison is restricted to a fairly homogeneous set of cases (table 106), robs the present data of any value in support of the therapeutic usefulness of the tantalum cuff. Conversely, however, the data by no means disprove the value of the cuff as a therapeutic device; the data simply do not fulfill the requirements of an unbiased treatment comparison. Cuff removal was studied in all cases wrapped in tantalum foil at the definitive suture, but no real evidence was developed to suggest that the practice, which became a very nearly routine procedure in some neuro- surgical centers, exerted any effect upon motor recovery. Table 107 pro- vides the data upon which this conclusion rests. 184

13. Use of Stay Suture In about 11 percent of all definitive nerve sutures and grafts the operation reports failed to specify whether stay sutures had been placed; they were definitely employed in about 25 percent of the remainder. In chapter II it was noted that resort to the stay suture was considerably more frequent among the sutures of some rosters than among others, but in the initial exploration of the material for any possible effect associated with the use of stay sutures this fact was ignored and all rosters were combined. It was also thought that sutured lesions in which the heavy stay sutures had been placed might be characterized by appreciably longer gaps than those in which stay sutures were not used, but analysis showed this not to be the case. Table 106.—Mean Power Following Complete Suture and Percentage of Affected Muscles Contracting Against Resistance, by Use of Tantalum Foil Wrapping at Definitive Suture, Lesions of Comparable Prognosis No cuff used Tantalum cuff Nerve and muscle Mean relative power, all Percent- age con- tracting against resistance Mean relative power, all cases Percent- age con- tracting against resistance Number of cases cases Number of cases High median Fl car rad . . 6 57.3 30.4 0 83 60 0 14 10 14 41.4 13.4 20.6 86 60 64 Fl. poll. long . . . 5 5 Opponens ... Low median Fl. car. rad . . 1 2 6 64.0 100 1 1 5 99.0 99.0 63.4 100 100 100 Fl. poll. long 55.0 11.7 100 50 Opponens High ulnar 21 21 21 16 53.1 31.2 12.8 13.1 90 76 52 44 15 16 16 13 64.4 26.3 7.1 14.3 100 Fl.dig. prof. 4&5.... Abd dig V 75 25 46 Low ulnar Fl. car. uln 2 4 10 8 65.0 100 100 70 63 5 9 16 11 55.8 38.6 16.3 19.8 80 Fl. dig. prof. 4 & 5 Abd. dig. V 52.8 13.2 21.4 67 56 64 1st don. inteross ... 403930—B7- -14 1*5

Table 106.—Mean Power Following Complete Suture and Percentage of Affected Muscles Contracting Against Resistance, by Use of Tantalum Foil Wrapping at Definitive Suture, Lesions of Comparable Prognosis—Continued No cuff used Tantalum cuff Nerve and muscle Mean relative power, all cases Percent- age con- tracting against resistance Mean relative power, all cases Percent- age con- tracting against resistance Number of cases Number of cases Radial Triceps 7 14 21 22 25.6 49.0 44.4 41.9 86 93 95 91 1 15 18 19 97.0 100 87 94 79 Brachiorad 57.7 45.4 40.2 Ext. car. rad Ext* car. uln Peroneal Tib. ant 17 17 17 16 23.2 12.8 7.2 24.3 59 59 47 69 10 10 10 10 37.8 9.5 10.0 25.6 70 30 30 70 Ext hall long . ... Peron long Tibial ( Jastroc & sol . . . 7 7 8 54.3 17.9 9.1 100 2 2 73.5 45.0 2.5 100 50 25 Tib post 43 38 Fl dig long 4 Sciatic-peroneal Tib. ant 24 25 24 8.0 4.0 2.2 7.8 25 16 8 28 19 19 19 19 1.7 2.3 16 16 16 Ext. dig. long Ext hall. long 2.3 1.2 Peron. long 25 16 Sciatic-tibial Gastroc. & sol 26 26 26 53.5 25.7 3.8 92 50 8 17 32.6 13.5 1.5 76 41 12 Tib. post 17 17 Fl. dig. long Comparisons of sutured lesions with and without stay sutures were made on the basis of mean relative power of affected muscles and are summarized in table 108. In two of the individual muscles the differences between means are significant in the statistical sense, but the direction of these two differences is not the same, and the overall pattern of variation among all the nerves is hardly more than suggestive of an effect favoring lesions without stay sutures. No more refined study of the possible role of the stay suture seemed worth while. 186

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Table 108.—Mean Relative Power of Affected Muscles Following Definitive Suture With and Without Stay Suture Nerve Gross site Muscle None used Used Statis- tical Number of cases Mean power Number of cases Mean power tests' Median High... Total . . High... Fl. dig. prof. 2 Abd. poll. brev. . . . Fl. dig. prof. 4 & 5 . Abd dig. V 96 127 176 200 148 70 171 138 153 146 144 107 116 111 110 133 133 133 132 95 102 101 22.14 13.86 31.14 7.18 8.11 39.74 10.70 12.93 38.69 26.78 18.37 15.47 8.84 7.25 15.50 4.82 2.22 1.20 4.02 46.74 3.58 3.22 33 49 45 52 35 24 59 36 56 55 58 32 36 35 35 67 68 66 68 57 61 61 12.88 11.02 20.56 5.00 6.86 30.27 15.19 8.19 35.63 18.45 12.33 14.38 7.50 8.43 17.29 5.90 1.84 4.24 4.04 43.77 1.07 .82 NS NS Ulnar * Low. . . Total. . Total.. 1st. dors. inteross. . Fl. dig. prof. 4 & 5. Abd. dig. V NS NS NS NS NS NS NS NS NS NS NS NS NS Radial . . 1st. dors. inteross. . Ext. car. rad Ext die Ext. poll. long .... Peroneal. . . . Tib. ant Peron. long Sciatic- peroneal. Total . . Tib. ant NS Ext. hall. long * Sciatic- tibial. Total.. Gastroc. & sol NS NS NS NS Fl. dig long Fl. hall. long 1 Results of tests are abbreviated as follows: NS=Not significant. *=Significant at .05 level. 14. Technique of the Definitive Lysis About 30 percent of the definitive lyses were internal, i. e., involved saline injection (25 percent) or fascicular dissection (5 percent), and the opportunity was taken to compare internal with external lyses to the extent permitted by this material, on the frank assumption that the two groups were comparable to begin with. The comparisons are made in table 109 on the basis of mean relative power. Although large and significant differences are observed for the gastrocnemius and soleus in sciatic-tibial lesions, and for the extensor hallucis longus in peroneal, for the median, ulnar, and radial muscles the differences are so small that one cannot con- clude that there is adequate evidence of any general effect common to all nerves. If, in a larger sample, there were a clear difference between external and internal lyses on nerves of the lower extremity, one would be inclined to believe that it reflected a selection of cases with more intra- neural damage rather than that the procedure per se had an untoward effect. 190

15. Training of Surgeon As reported in chapter II, the limited exploration which was made of level of training in association with other variables contained no real suggestion that the lesions operated upon by the better-trained differed in prognosis from those operated upon by surgeons with no special training. Training was first studied on the basis of the definitive suture, and when no general association with motor recovery was found, it was repeated on the basis of the first suture. The details of the latter comparison appear in table 110. However, the latter analysis, covering both mean power and the percentage contracting against resistance, led to the same con- clusion. Since any confounding of training and initial prognosis may be rather more complex than would be revealed by such exploration as it has been possible to do on these data, it cannot be argued that level of training actually exerted no general effect upon motor recovery during World War II. However, it is plain that no case for such an effect can be built upon these data. It will be noted in table 110 that the roughly 30 tibial lesions sutured by trained neurosurgeons did considerably better than the approxi- mately 40 sutured by men with less training. This was noted in all 3 tibial muscles, although only 1 is shown here. 16. Summary Despite the obvious difficulties inherent in the search for treatment effects in a clinical series, from the foregoing study of some of the practical details of surgical management a number of clear-cut conclusions emerge together with suggestive evidence of effects. One of the most definite and most important of these concerns elapsed time: For all nerves generally it seems rather well established by these data that the final level of motor recovery is maximal for early sutures, and that subsequent delay in suture involves a variable loss which averages about 1 percent of maximal performance for every 6 days of delay. The very earliest, or emergency, sutures done within 19 days of injury do as well at follow-up as other early sutures, but only after half of them had been resutured. Although the effect of time seems clearly a general one, its magnitude varies not only by nerve but also by muscle within the set innervated by a particular nerve. The effect seems especially large in distal muscles, and in those innervated by the radial and the peroneal. Whether sutures were done overseas or in the Z/I is of no prognostic importance if one takes time into account; the real advantage of overseas sutures seems adequately explained by the difference in time from injury to repair. The effect of time also confounds that of gap, there being a definite correlation between the two. Information about gap is of less prognostic value than information about time, but if time be ignored the effect of gap is a significant one; there is an average loss of about 6 percent per cm. from the optimal motor recovery following sutures on the shortest gaps, until the critical limit is reached when suture becomes impossible. 191

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Such special operative features as transposition and extensive mobiliza- tion have no demonstrably adverse influence upon motor recovery. Al- though lesions first treated by bulb suture recover less well than others, when differences in length of gap are taken into account it is plain that therein lies the source of the disadvantage; otherwise lesions treated by bulb suture do as well or as poorly as others. The operator's report on the gross appearance of nerve ends prior to anastomosis correlated to some extent with that of the neuropathologist and is weakly associated with eventual motor recovery. The operator's report of tension, in contrast, is of no obvious prognostic value. World War II saw extensive use of tantalum sutures, but the present series makes it plain that such sutures were followed by the same recovery as those done by silk. A special series of plasma glue sutures was also studied and after suitable allowances for differences in the selection of the cases their motor recovery at followup proved to be indistinguishable from those done by silk or tantalum. Sutured lesions on which cuffs were used seemed to recover more com- pletely than those on which the foil was not used, but perhaps only because the initial selection of cases favored those on which tantalum foil was used. The use of stay sutures seemed to exert no particular influence upon the eventual level of motor recovery. Neurolyses were done in several ways, but no evidence was found that internal and external neurolyses differed in their effect on recovery. No demonstrable effect may be attributed to the training of the operator performing the definitive suture. In most general terms, the analysis serves to identify those aspects of management which do, and those which do not, appear to exert a significant influence upon motor recovery. Of all the characteristics studied, time from injury to suture exerts the greatest influence, and yet this factor alone does not explain much of the great variation seen in the final level of recovery. Moreover, some of the apparent influence of other treatment factors is associated with that of time, so that any overall measure of the extent to which differences in management explain variation in final recovery would not greatly exceed that observed for time alone and would hardly be impressive in any event. In addition to the treatment variables, however, as already shown in the earlier sections of this chapter there are many characteristics of the nerve injury itself, including associated lesions of various kinds, which also have a marked bearing on motor recovery. The most important of these is the character of the lesion itself, insofar as it is reflected in the surgeon's choice between suture and lysis.

F. COMBINED INFLUENCE OF ADVERSE FACTORS UPON MOTOR RECOVERY FOLLOWING SUTURE Although chief attention has been given to the influence of individual variables affecting motor recovery, there is considerable interest in com- bining this information for use in prognosis. How good will recovery be if no unfavorable factors intervene? What is the total impact of several unfavorable factors? Such questions may be approached in a variety of ways; only the simplest has been used here. At the outset a set of factors was chosen on the basis of apparent influence upon recovery when studied individually. Sutured lesions were then classified according to presence or absence of these factors taken in all possible combinations. The recovery of each subgroup, and of patterns of subgroups, could then be studied. Of course, such subdivision dissipates the material into often quite small sub- groups, and there is need to combine these in some way. The simplest, but least exact, procedure is to group together lesions with the same number of prejudicial factors, regardless of what they might be. The latter tech- nique has been followed here, except that delay in definitive suture has been scaled as either 1 or 2 units of the score, depending on whether the suture was done in the interval 90-269 days after injury or 270 or more. Only the median and ulnar nerves have been studied in the fashion out- lined above, with a separation into high and low lesions, and with recovery based on the relative power of the following muscles: Median muscles Ulnar muscles flexor pollicis longus flexor digitorum prof. 4 & 5 flexor digitorum profundus 2 abductor digiti quinti abductor pollicis brevis first dorsal interosseus Perhaps the most important conclusion which emerges from such an analysis is that even lesions characterized by none of the prejudicial factors listed above do not have very high recovery ratios if strength is used as the criterion. Table 111 gives both indices of recovery for these cases, which are, of course, unfortunately few in number. In addition, the material on one muscle is not independent of that on another innervated by the same nerve. Nevertheless, it seems clear that absence of the selected prejudicial factors will not characteristically insure a return to anything approaching normal strength of movement. Failure to contract at least perceptibly, of course, is rare in this small, selected series, but the mean power of muscles contracting against resistance seems about average, according to the values of table 51 (p. 91). Once the median cases are subdivided in the fashion described, there are only a few groups containing as many as 10 lesions, and for none of these is the mean power (of all examined muscles, whether contracting or not) remarkably out of line. However, for both high and low lesions there are small groups which suggest that recovery of the most distal muscles may be especially susceptible to the influence of the several variables selected. For example, the average power of the abductor pollicis brevis was found earlier 198

Table 111.—Percentage of Affected Muscles Contracting and Mean Power of Muscles Contracting Against Resistance, Median and Ulnar Lesions Treated by Complete Suture With No Prejudicial Factors, by Gross Site High Low Power of muscles contracting against resistance Power of muscles contracting against resistance Muscle Perceptible contraction Perceptible contraction N ' Percent NI Mean NI Percent NI Mean Median Fl. poll. long 5 100 2 52 3 100 2 48 Fl. dig. prof. 2. . . 8 100 5 33 4 100 3 53 Abd.poU.brev... 7 100 3 47 10 100 4 26 Ulnar FLdig. prof. 4&5 Abd. dig. V 24 24 100 88 11 5 43 23 12 20 100 10 11 58 23 95 1st. dors. inteross. 19 95 5 31 16 88 6 17 1 N represents the number of cases upon which the percentage or the mean is based. to be 12 percent of normal for high lesions and 15 percent for low lesions. Among the high lesions there is one group of 18 cases with moderate delay in repair plus an associated nerve injury, for which the average power is only 5 percent. There is another group of 20 high lesions with these same prejudicial characteristics plus arterial injuries, for which mean power is 6 percent. Finally, there is a group of 11 low lesions with long delay plus associated bone injury for which mean power is 10, in comparison with the overall average of 15. Since the groups are so small, some grouping is necessary to any analysis, and in table 112 are given summary figures for median lesions grouped according to the score obtained by counting the number of prejudicial factors, except that a long delay adds two units. There may be many different ways of reaching the same score, but inspec- tion of the data does not suggest that combining cases on this basis is unwise. In each of the comparisons of table 112 the group with the highest score appears in an unfavorable light, but only for the abductor pollicis brevis is the relationship an impressive one. Here the lesions with the largest num- ber of prejudicial factors have means of only 15 to 20 percent of those computed for the lesions with the smallest number of such factors. 199

For the ulnar nerve variation in recovery does not follow the scoring ex- cept for the first dorsal interosseus, for which the data are much like those for the abductor pollicis brevis. Table 113 contains the mean values arranged as in table 112. Table 112.—Mean Relative Power of Affected Muscles Following Complete Suture, Median Lesions by Site and Score on Presence of Prejudicial Factors Muscle Score Fl. poll. long. FL prof. ind. 2 Abd. poll. brev. N i Mean "« Mean N' Mean High lesions 1-2 20 26 29 22 19 26 3 36 35 53 25 36 12 4 29 26 44 21 26 4 5-7 12 15 18 8 14 5 Total 97 28 144 21 95 12 Low lesions 0-1 12 56 26 19 0-2 22 55 2 20 61 25 22 3-7 20 22 26 37 3 31 10 4-7 17 3 Total 42 40 58 50 99 14 1 N represents the number of cases upon which the mean is based. 200

Table 113.—Mean Relative Power of Affected Muscles Following Complete Suture, Ulnar Lesions by Site and Score on Presence of Prejudicial Factors Score Muscle Fl. dig. prof. 4 & 5 Abd. dig. 5 1st dors. inteross. N' Mean N' Mean N' Mean High lesions 1 18 26 22 5 15 10 2 46 28 51 5 41 12 3 98 37 109 10 77 9 4 63 23 71 5 53 6 5-7 28 26 35 4 27 1 Total 253 30 288 7 213 8 Low lesions o 12 48 20 12 16 6 1 24 41 55 14 43 17 2 43 44 98 15 69 15 3 59 7 42 10 3-6 30 27 4-6 24 11 21 5 Total 109 39 256 13 191 12 1 N represents the number of cases upon which the mean is based. 403980—B7- -15 201

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Peripheral Nerve Regeneration: A Follow-Up Study of 3,656 World War II Injuries Get This Book
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In peacetime, the busiest civilian clinics do not see enough peripheral nerve injuries to permit authoritative conclusions to be drawn about their management. In World War I, large numbers of these injuries were skillfully cared for by a small group of pioneer neurosurgeons, but there was no comprehensive follow-up and the opportunity to use the experience to the fullest possible extent was lost.

The publication of Peripheral Nerve Regeneration: a Follow-Up Study marks the end of a huge clinical research program that began in 1943, in the course of World War II. The program was participated in by more than a hundred of the neurosurgeons who served in the Medical Corps, as well as by many neurologists, neuroanatomists, neurophysiologists, neuropathologists, physical therapists, statisticians, and representatives of the administrative personnel of every echelon of command in the Army Medical Corps. Later the program was also participated in by representatives of the Veterans Administration and the National Research Council.

The primary purpose of this study was to evaluate the suites of peripheral nerve injuries sustained in World War II, with the hope of standardizing such treatment for future wars and, where possible, for similar injuries of civilian life. The secondary purpose of this study was to discover nerve injuries among veterans of all services that still required remedial measures. Peripheral Nerve Regeneration: a Follow-Up Study describes the final level of regeneration in representative cases of complete suture, neurolysis, and nerve graft, examines the apparent influence of gross characteristics or the legion, and or associated injuries, upon final result, and evaluates predictions of final recovery based on gross and histologic study of tissue removed at operation. The report of this study of postwar nerve regeneration provides for the surgeons of the future a body of information upon which they may guide repair of injured peripheral nerves and initiate needed orthopedic rehabilitation.

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