Male and Female Cervical Spine Biomechanics and Anatomy: Implication for Scaling Injury Criteria.

There is an increased need to develop female-specific injury criteria and anthropomorphic test devices (dummies) for military and automotive environments, especially as women take occupational roles traditionally reserved for men. Although some exhaustive reviews on the biomechanics and injuries of the human spine have appeared in clinical and bioengineering literatures, focus has been largely ignored on the difference between male and female cervical spine responses and characteristics. Current neck injury criteria for automotive dummies for assessing crashworthiness and occupant safety are obtained from animal and human cadaver experiments, computational modeling, and human volunteer studies. They are also used in the military. Since the average human female spines are smaller than average male spines, metrics specific to the female population may be derived using simple geometric scaling, based on the assumption that male and female spines are geometrically scalable. However, as described in this technical brief, studies have shown that the biomechanical responses between males and females do not obey strict geometric similitude. Anatomical differences in terms of the structural component geometry are also different between the two cervical spines. Postural, physiological, and motion responses under automotive scenarios are also different. This technical brief, focused on such nonuniform differences, underscores the need to conduct female spine-specific evaluations/experiments to derive injury criteria for this important group of the population.