Timing of lower extremity frontal plane motion differs between female and male athletes during a landing task.

BACKGROUND: Female athletes are at a greater risk for noncontact anterior cruciate ligament injuries than male athletes. Gender differences in frontal plane kinematics (hip adduction, knee valgus, and ankle eversion) and temporal relationships that make up the components of dynamic knee valgus may explain this discrepancy. HYPOTHESIS: The authors hypothesized that women would reach peak frontal plane kinematic values earlier during landing compared with their male counterparts. STUDY DESIGN: Controlled laboratory study. METHODS: Hip, knee, and ankle 3-dimensional kinematics were measured using high-speed motion capture in 10 National Collegiate Athletic Association Division I female athletes and 10 male practice squad athletes during a drop-jump landing. Independent t tests were used to analyze each dependent variable to identify differences between genders. RESULTS: Maximum hip adduction, knee valgus, and ankle eversion occurred earlier in women than in men (mean differences 33.7% of stance [95% CI, 20.2%-47.2%], 41.7% [95% CI, 31.5%-51.6%], 16.5% of stance [95% CI, 7.3%-25.6%], respectively). Maximum hip adduction and knee valgus occurred before maximum knee flexion in women and after in men (mean differences 0.11 seconds [95% CI, 0.05-0.18 seconds], 0.19 seconds [95% CI, 0.13-0.25 seconds], respectively). Maximum ankle eversion occurred earlier in women than in men (mean difference 0.06 seconds [95% CI, 0.01-0.11 seconds]). There was a significant difference between genders for angular velocity of knee valgus (mean difference = 25.53 deg/sec [95% CI, 8.30-42.77 deg/sec]). CONCLUSION: Frontal plane kinematic temporal relationships at the hip, knee, and ankle differ between genders. The components of dynamic knee valgus peak during the deceleration phase in women and during the acceleration phase in men during a drop-jump landing. These data suggest that men and women employ a completely different kinematic landing/jumping strategy and that women land and collapse very rapidly into valgus compared with their male counterparts. CLINICAL RELEVANCE: The differences in timing of the components of dynamic knee valgus between women and men may contribute to the increased risk of noncontact anterior cruciate ligament injuries in female athletes. There may be implications for neuromuscular reeducation training in those at risk for anterior cruciate ligament injury so the components of dynamic valgus occur later in the landing phase of jumping.

A 5° medial wedge reduces frontal but not saggital plane motion during jump landing in highly trained women athletes.

Lower extremity mechanics during landing have been linked to traumatic and nontraumatic knee injuries, particularly in women's athletics. The effects of efforts to mitigate these risks have not been fully elucidated. We previously reported that a 5° medial wedge reduced ankle eversion and knee valgus. In the present report we further investigated the effect of a 5° medial wedge inserted in the shoes of female athletes on frontal plane hip motion, as well as ankle, knee, hip, and trunk saggital plane motion during a jump landing task. Kinematic data were obtained from 10 intercollegiate female athletes during jump landings from a 31 cm platform with and without a 5° medial wedge. Hip adduction was reduced 1.98° (95% CI 0.97-2.99°) by the medial wedge but saggital plane motions were unaffected. A 5° medial wedge reduces frontal plane motion and takes the knee away from a position associated with anterior cruciate ligament injury and patellofemoral pain syndrome. Although frontal plane motion was not captured it is unlikely to have increased in a bilateral landing task. Thus, it is likely that greater muscle forces were generated in these highly trained athletes to dissipate ground reaction forces when a medial wedge was in place. Additional investigation in younger and lesser trained athletes is warranted to assess the impact of orthotic devices on knee joint mechanics.