LOWER-LIMB MORPHOLOGY AND RISK OF OVERUSE INJURY AMONG MALE INFANTRY TRAINEES

The effect of anatomic variation on the risk of overuse injuries has n ot been adequately evaluated. To determine the association of several common anatomic characteristics (gem varum, genu valgum, genu recurvat um, and lower limb length differences) with risk of overuse injury, we made prospective morphologic measurements of young men prior to begin ning 12 wk of Army infantry training. The training included frequent r unning, marching, calisthenics, and other vigorous activities. Lower e xtremity anatomic landmarks were highlighted, and front- and side-view photographic slides were taken of the 294 study volunteers. The slide s were computer digitized, and the following measures calculated: pelv ic width to knee width ratio (to assess genu valgum/varum), quadriceps angle (Q-angle), knee angle at full extension, and lower limb length differences. The cumulative incidence of lower limb overuse injury was 30%. Relative risk (RR) of overuse injury was significantly higher am ong participants with the most valgus knees (RR = 1.9). Those with Q-a ngle of more than 15 degrees had significantly increased risk specific ally for stress fractures (RR = 5.4). Anatomic characteristics were as sociated with several other types of injuries, including pain and nona cute muscle strain due to overuse. This pilot study provides evidence that some lower limb morphologic characteristics may place individuals at increased risk of overuse injuries.