Comparison of Medial Knee Displacement Assessment on the Overhead Squat and Landing Error Scoring System

Abstract

Medial knee displacement (MKD) in females has been associated with increased risk for anterior cruciate ligament injury (ACL). It can be reliably detected using clinical movement screens and is readily modifiable through corrective exercise. The Overhead Squat (OHS) and Landing Error Scoring System (LESS) are both valid indicators of MKD. PURPOSE:To determine concordance between evaluation of MKD from the OHS relative to the more dynamic LESS. METHODS: Female U.S. Military applicants (n=84, 20.6±2.7 yrs, 161.4±6.7 cm, 60.4±8.3 kg) from the Baltimore MEPS performed the OHS and LESS prior to entering military basic training. MKD for both tests was evaluated dichotomously: 0 indicating no MKD and 1 indicating the presence of MKD. The OHS was evaluated in real time. MKD on the LESS was evaluated at maximum knee flexion. McNemar’s Test for non-homogeneity was performed to determine paired proportions of MKD between the OHS and LESS. RESULTS: A total of 55 females (65.4%) displayed MKD on the OHS, and 76 females (90.5%) had MKD on the LESS. McNemar’s test showed non-homogeneity for MKD detection on both the OHS and LESS (Χ2= 15.21, p<0.001); the majority of females (60.7%, n=51) who displayed MKD on the OHS also displayed MKD on the LESS. However, 29.8% (n=25) of females who displayed MKD on the LESS did not display MKD on the OHS. Only 4 (4.8%) females did not display MKD on either screen. CONCLUSION: The OHS and LESS are both commonly used clinical screens for assessing MKD, a risk factor for ACL injury in females. Although the majority of females who displayed MKD on the OHS also displayed it on the LESS, 29.8% only displayed MKD on the more dynamic LESS suggesting that MKD manifests differently between static and dynamic tasks. Both screens have been biomechanically validated as indicators of MKD, but the dynamic task requirements of the LESS may be more representative of sport-specific movement. Further analyses comparing injury rates in recruits with MKD detected by OHS versus LESS are pending. The LESS could be a more accurate test for assessing dynamic MKD as a readily modifiable risk factor for ACL injury in females.