Context: A relationship between a positive history of sport-related concussion (SRC) and lower extremity (LE) injury has been well established in the literature.

Objective: The purpose of this study was to determine if biomechanical differences exist during a double limb jump landing (DLJ) between athletes who had been released for return to play after SRC and healthy matched controls (Healthy).

Design: Cross-Sectional Study

Setting: Health system-based Outpatient Sports Medicine Center

Participants: 21 participants (16.33±12.7 days out from being released to return to sport after SRC) (age: 15.38±1.77; height: 169.23±8.59; mass: 63.43±7.39) were compared to 21 age, sex, activity-matched healthy controls (age: 15.36±1.73; height: 169.92±11.1; mass: 65.62±12.08). No significant differences existed between groups for descriptive data.

Main Outcome Measure(s): Biomechanical performance during DLJ was assessed using Motion Capture System and force plates. The average of five consecutive trials was used to calculate lower extremity joint kinetic and kinematics. Variables of interest included internal knee extension moment, internal varus moment, and total sagittal plane knee displacement for both the dominant and non-dominant limbs. Independent t-tests were performed to examine the differences between SRC and Healthy groups for variables of interest.

Results: The SRC group demonstrated greater internal knee extension moments on their dominant (KEDomDiff=–.028±.009; p=.003) and non-dominant (KENonDomDiff=–.018±.007, p=.019) limbs. The SRC group also demonstrated greater internal varus moments on their dominant (VDomDiff=.012±.004, p=.005) and non-dominant (VNonDomDiff=.010±.003, p=.005) limbs. For sagittal plane knee displacement, the SRC group demonstrated less knee flexion displacement on their dominant (DispDomDiff=–12.56±4.67, p=.011) but not their non-dominant limb (DispNonDomDiff=–8.30±4.91, p=.099).

Conclusions: Athletes who have been released for return to sport after SRC land in greater knee valgus compared to healthy matched controls.

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