JUMP-LANDING KNEE FLEXION ANGLE DIFFERENCES BETWEEN GENDER

Abstract

Several investigators have speculated that ACL injuries frequently occur with the knee at small flexion angles during the jump-landing motion. It has been reported that women tend to land in a more erect position with less knee flexion, thus creating greater knee extensor loads and perhaps leading to a gender bias for females increased risk for ACL injury. PURPOSE To assess jump-landing knee flexion angle differences between gender while performing a modified basketball rebounding task. METHODS Knee kinematics of 25 female (age = 20.01 ± 1.53 yrs, height = 1.63 ± .09 m, weight = 59.36 ± 9.37 kg) and 15 male (age = 20.40 ± 1.30 yrs, height = 1.81 ± 0.8 m, weight = 77.21 ± 10.28 kg) collegiate aged students were collected. Subjects ran 4 meters and performed a stop-jump maneuver to grab a basketball set at 80% of maximum jump height. The dependent variables measured were knee flexion angles at initial ground contact and knee angular displacement flexion angle during the landing phase of the task. RESULTS A univariate analysis of covariance was conducted on each dependent variable with jump height used as the covariate. A statistical difference was found between gender [F(1,37)=4.82, p = .034) for knee flexion angle at initial ground contact with females landing in less knee flexion at initial ground contact (mean=19.61, SD=4.06) as compared to males (mean=21.52, SD=4.17). No statistical differences were found between gender for knee angular displacement flexion angles. CONCLUSIONS Females land in a more erect knee position at initial ground contact while performing a modified basketball rebounding task. Even though statistical significance was found between gender for knee flexion angles at initial ground contact, a two degree difference between genders does not seem clinically relevant. Further research is warranted on jump-landing differences between gender during different components of a jump-landing task (e.g., stop-jump) and movement requirements (e.g., anticipatory). Supported by Injury Prevention Research Center at University of North Carolina at Chapel Hill