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[Purpose] Increased femoral anteversion may occur with hip internal rotation and valgus knee alignment upon landing and is considered a risk factor for anterior cruciate ligament injury. We examined the relationship between femoral anteversion and joint motion and muscle activity of the lower extremity in terms of the risk factors for anterior cruciate ligament injury. [Subjects] Sixteen healthy females were divided on the basis of femoral anteversion into low and high groups. [Methods] Femoral anteversion was assessed using Craig's test. We performed kinematic analysis and measured the electromyography activity of the lower extremity upon left single-leg landing. [Results] The high group had a significantly lower hip flexion angle and higher knee flexion and valgus angles than the low group. The rectus femoris showed significantly greater electromyography activities in the high group than in the low group. [Conclusion] These results suggest that increased femoral anteversion results in lower hip flexion angle, higher knee valgus alignment, and greater rectus femoris muscle activity, leading to anterior tibial displacement upon single-leg landing. Increased femoral anteversion may be a potential risk factor for anterior cruciate ligament injury.

[Purpose] The purpose of this study was to evaluate the relationship between malalignment and lower-extremity injury and to determine the optimal dynamic alignment of the lower extremity with wall squats. [Subjects and Methods] Healthy individuals from one therapy school were enrolled and assigned to a wall squat normal or abnormal group based on their forms during wall squats. The abnormal group was found to be more prone to lower-extremity injury on three-dimensional motion analysis. Eight students from each group were randomly chosen for the study. The effects of single-leg landing movements were assessed using three-dimensional motion analysis. [Results] In the sagittal plane, significant flexion of the hip and knee joints occurred 0.02 and 0.04 seconds after initial foot contact with the ground in the normal and abnormal groups, respectively. In the frontal plane, significant adduction of the hip joint occurred at 0.07 seconds in the abnormal group. [Conclusion] The abnormal group tended to display later flexion of the hip and knee joints and narrower hip, knee, and ankle range of motion than the normal group, suggesting that dynamic alignment of the lower extremity in the abnormal group likely made them susceptible to injury.