654 MEP017 – Classification of valgus and varus knee wobbling as a screening method to detect risk of anterior cruciate ligament injury in female basketball athletes

AbstractBackground Dynamic, sequential analysis of knee kinematics is necessary to establish an effective screening method for risk of anterior cruciate ligament (ACL) injuries, since dynamic knee valgus is considered a critical factor. Repeated valgus and varus movement or "knee wobbling (KW)" is considered abnormal knee movement. We hypothesized that KW at low knee flexion increases the risk of ACL injury.Objective The purpose of this study was to identify differences in knee kinematics and KW of young basketball athletes during four tasks, comparing those with and without subsequent ACL injuries over a three-year period. Relationships between parameters were also analyzed.Design A prospectively designed, case-control studySetting Laboratory measurementParticipants 272 female basketball athletes from junior high and high schools participated.Assessment of Risk Factors Participants stood on one leg, performed slow, single-leg squats and single-leg jump landings with both legs, and double-leg drop landings. Two-dimensional videos from the front and side were captured. Main Outcome Measurements Knee kinematics and characteristics of KW, which were classified into valgus and varus movement, were analyzed. KW was calculated as the ratio of knee frontal angular velocity to knee sagittal angular velocity. Participants with and without subsequent ACL injuries were compared after a three-year period.Results Ten athletes suffered ACL injuries during follow-up. There were no significant differences in knee kinematics and KW between those with and without subsequent ACL injuries (Table 1 and 2). However, athletes who later suffered ACL injuries differed when classified by valgus or varus KW during slow single-leg squats compared to single-leg standing (Figure 1 and 2). Maximum knee valgus angle and varus KW were correlated (p = 0.025), as were varus KW and varus excursion angle (p = 0.005). Conclusions Direction of KW during slow, single-leg squats may identify potential risk of ACL injury.View this table:View inline View popup Abstract 654 Table 1 Knee kinematics and characteristics of knee wobbling during single leg standingView this table:View inline View popup Abstract 654 Table 2 Knee kinematics and characteristics of knee wobbling during slow single leg squatDownload figure Open in new tab Download powerpoint Abstract 654 Figure 1