A Kinematic Analysis of the Knee During Single-Leg Drop Landing

Abstract

The goal of this study was to examine the kinematic movement of the knee during a single-leg drop landing specific to an individual female subject. Athletes typically perform single-leg and double-leg landings from various heights during sporting competition. The majority of anterior cruciate ligament injury is accounted for by non-contact mechanisms, such as single-leg landings. A subject specific study was designed to compare the effect of two landing styles, single-leg arms above and single-leg arms across, at landing heights relative to the subjects’ maximum vertical jump. Kinematic analysis was done at five points: initial contact, peak vertical ground reaction force, peak joint reaction force, maximum knee flexion, and maximum valgus angle. An ANOVA post-hoc analysis yielded no statistical significance (p<0.05) between landing styles at varied heights, as well as varied heights within each landing style. This information leads to the hypothesis that landing styles and ground reaction forces are not significant in ACL injuries, but movement and control of the knee during landing are. Each landing trial displayed a “coup-countrecoup” effect, where the subjects’ knee position landed in a valgus position, translated into a deeper valgus position, and then translated back into varus while reaching maximum knee flexion. The coup-countrecoup effect is hypothesized to be the detrimental movement that is causing the rupture of ACL’s. The control of knee motion plays an important factor during sporting events and athletes should educate themselves to control their maneuvers during off season training.