Associations Between Single-Leg Postural Control and Drop-Landing Mechanics in Healthy Women

Context: Impaired postural control in single-limb stance and aberrant drop-landing mechanics have been implicated separately as risk factors for noncontact anterior cruciate ligament (ACL) injury, but associations between these variables has not been reported. Objective: To determine whether there are associations between single-limb postural control and drop-landing mechanics. Setting: University motion-analysis laboratory. Design: Single-leg-landing kinematic and kinetic data were collected after participants dropped from a hang bar. Postural-control variables COP excursion and velocity were assessed during single-leg barefoot standing on a force platform. Participants: A convenience sample of 24 healthy women. Main Outcome Measures: Pearson product-moment correlation coefficients. Results: Strong associations were measured between maximal knee-abduction moment and COP excursion (r = .529, P = .003) and average COP velocity (r = .529, P = .003). Strong inverse associations were measured between minimum hip-flexion angle and COP excursion (r = -.521, P = .003) and average COP velocity (r = -.519, P = .003). Conclusions: Participants with decreased postural control had higher knee-abduction moments and a more extended hip on landing, which have been implicated separately as risk factors for ACL injury. A longitudinal prospective analysis is needed to determine whether force-platform postural-control measures can identify athletes at risk for ACL injury.