Novel measures of frontal plane knee wobbling predict anterior cruciate ligament injury in Japanese female basketball players: A prospective pilot study.

BACKGROUND

To prospectively examine how lower extremity movement patterns during single-leg landings predict anterior cruciate ligament (ACL) injuries in adolescent Japanese basketball players during a 3-year follow-up period.

METHODS

44 female basketball players, whose knee kinematics were measured using 2-dimensional video analysis during single-leg jump landings from a box 30 cm high. Peak knee valgus angle and knee wobbling during the landing task were primary measures of injury risk. Knee wobbling, defined as repeated knee valgus/varus movement, was calculated from relative frontal to sagittal motions (RFM) at 6, 12, 18, 24, and 30° of knee flexion. Higher RFM indicates that knee frontal movement is large compared to changes in knee flexion during landing. Knee valgus angle and RFM were compared prospectively between ACL-injured and uninjured athletes during a 3-year follow-up period.

FINDINGS: Peak knee valgus angles at initial contact for injured and uninjured athletes were not significantly different (12.3 ± 2.4° vs. 14.8 ± 4.1°; p = 0.15). Five of six ACL-injured knees (83.3%) presented knee wobbling during landing. RFM at 18° knee flexion was significantly greater in injured athletes (0.42 ± 0.52) compared to uninjured athletes (0.10 ± 0.31; p = 0.02).

INTERPRETATION: While peak knee valgus angle did not predict subsequent ACL injuries, RFM at 18° knee flexion could find the difference between groups. This study suggests that frontal plane knee wobbling may be indicative of impaired lower extremity control and thus a potential screening tool and intervention target for ACL injury prevention in female basketball players.