KINEMATICS AND KNEE INJURIES IN RUNNERS WITH LOW ARCHES

Abstract

Gender differences in injury incidence at the knee have been reported in the literature. Additionally, medial longitudinal arch structure has been suggested to effect injuries at the knee. However, the relationship between gender and arch structure as it relates to injury has not been investigated. PURPOSE: To evaluate injury histories and compare rearfoot and knee kinematics in male and female runners with low arches. METHODS: Twenty runners (10 female and 10 male) with extremely low arches were evaluated. All subjects were screened for inclusion in the low-arched group using an arch ratio method. Retroreflective markers were affixed to the pelvis, thigh, shank and foot unilaterally. A standing calibration trial was collected and subjects then ran along a runway at a fixed speed. Ten trials were collected. Data were sampled at 120 HZ using a six camera motion analysis system. Three-dimensional joint kinematics were calculated during the stance phase of gait. Knee flexion excursion, peak knee flexion, peak knee abduction, rearfoot eversion excursion and peak rearfoot eversion were calculated and compared using a Student's t-test (p ≤ 0.05). Running-related injuries were reported via questionnaire. RESULTS: Females exhibited lower knee flexion excursion when compared to males, although not significantly (p = 0.11). Both groups exhibited a similar peak knee flexion angle (p = 0.34). Low-arched female subjects in the current study showed a trend toward greater knee flexion at heel strike than male runners (p = 0.12). Females demonstrated significantly higher peak knee abduction when compared to males (p = 0.04). No significant difference was observed between the groups in rearfoot eversion excursion (p = 0.39) while the female group exhibited a lower peak rearfoot eversion (p = 0.03). Finally, low-arched females reported more than twice as many knee injuries as their male counterparts (14 vs. 6). CONCLUSION: Low-arched females appear to exhibit more control of peak frontal plane angle (eversion) at the ankle while exhibiting less frontal plane control at the knee (abduction). This may be one factor contributing to the increased number of knee injuries in the low-arched female runner when compared to males. Further investigation should focus on medial longitudinal arch structure in the female athlete and its relationship to running or landing-related injuries. The results of these data suggest that similar structural deviations may have different relationships to running mechanics and injuries between male and female athletes.