ventions—including pilot training, air traffic control, aircraft design, and the use of safety belts—has been institutionalized to reduce passenger fatalities on U.S. commercial aircraft in 1996 to 1.8 per million passenger enplanements (NTSB, 1998). Such integration of approaches from multiple disciplines is crucial to injury prevention research.
Injury biomechanics has been a fundamental discipline in experimental studies of injury, especially injury causation. Experimental biomechanics reproduces the circumstances of injury under well-controlled laboratory conditions and examines structural and biologic responses. The work of Hugh DeHaven and William Haddon defined the field of injury biomechanics by describing the implications of abrupt dissipation of mechanical energy (see also Chapter 1 and Baker et al. ). Injury biomechanics research uses the principles of mechanics to explore the physical and physiologic responses to impact, including penetrating and nonpenetrating blows to the body (NRC, 1985). Classically, injury biomechanics research has focused on injuries in their acute phase, establishing the causative forces or motions that provoke the injury, allowing countermeasures to be designed and tested. Yet, biomechanics has many applications in injury research, including testing the efficacy of interventions involving product design. Currently, the field of biomechanics includes investigators studying robotics, physical therapy, orthopedics, physical and sports medicine, exercise science, limb prosthetics, orthotics, and tissue engineering. This multidisciplinary science promises to provide the scientific and technical knowledge to develop strategies that will prevent injury or assist impaired neuromuscular systems (IOM, 1997).
Biomechanics research has established injury tolerance levels for many types of body tissue and has elucidated many of the biological processes that affect the injury process. The most complete picture of injury tolerances, pathophysiology, and reparative processes involves adult bone and connective tissue (McElhaney et al., 1976; Nahum and Melvin, 1993). Yet, despite significant strides in the past decade, the biomechanical properties of the brain and the biologic response of the brain to injury are not as well characterized. This variability in the knowledge base of injury biomechanics is also evident in the sophistication of interventions available. Techniques for the prevention and treatment of orthopedic injury are vast, ranging from hormonal supplementation to strengthen bone in order to prevent fracture (Folsom et al., 1995) to successful treatment for the nonunion of fractures by electrical stimulation (Esterhai et al., 1986). The options available to the clinician treating traumatic brain injury are essentially limited to minimizing secondary injuries due to brain swelling or hemorrhage (Chesnut, 1997).