Core Stability, Knee Muscle Strength, and Anterior Translation Are Correlated with Postural Stability in Anterior Cruciate Ligament-Reconstructed Patients

Objective The purpose of this study was to investigate the relationship of postural stability and lower extremity performance with core stability, knee laxity, and muscle strength in patients with anterior cruciate ligament reconstruction. Design Twenty-eight anterior cruciate ligament-reconstructed subjects were included in the study. Anterior knee laxity tests, isokinetic knee muscle strength tests, and core stability tests were performed. Single-limb postural stability was assessed in both eyes-open and eyes-closed positions on a static surface and an eyes-open condition on a foam surface. A single-legged hop test was performed to assess lower extremity performance. To detect differences between the operated and healthy leg, a Mann-Whitney U test was performed, and a correlation analysis was performed using the Spearman correlation coefficient. Results Knee muscle strength and laxity were different between the operated and healthy legs (P < 0.05). Postural stability scores correlated with core stability tests (P < 0.05) in both the operated and healthy legs. In the operated leg, knee laxity and muscle strength correlated with the mediolateral sway index on a foam surface (P < 0.05). Knee flexor and extensor muscle strength correlated with the single-legged hop for both legs (P < 0.05). Conclusions Decreased core stability, decreased knee muscle strength, and increased knee laxity correlated with single-limb postural stability. Better hop performance was demonstrated with better knee flexor and extensor muscle strength and was independent from core stability.