Association of the center of pressure position, trunk and lower limb joint kinematics with knee extensor moment during single-leg squatting after anterior cruciate ligament reconstruction.

BACKGROUND

Reduced knee extensor moment after anterior cruciate ligament reconstruction is associated with quadriceps weakness, increased risk of second anterior cruciate ligament injuries, and early onset of knee osteoarthritis. This study investigated the association between the knee extensor moment, anterior-posterior center of pressure, and trunk and lower limb joint angles during single-leg squatting following anterior cruciate ligament reconstruction.

METHODS

Twenty-one patients who underwent anterior cruciate ligament reconstruction performed a single-leg squatting with both legs. Regression analyses were performed to examine the association between the knee extensor moment, anterior-posterior center of pressure, and trunk and lower limb joint angles, all of which were measured using a 3-dimensional motion analysis system.

FINDINGS: The knee extensor moment was predicted by the anterior-posterior center of pressure in the involved limb (P = 0.038, R2 = 0.208). The knee extensor moment was significantly predicted by the knee flexion angle (involved: P = 0.003, R2 = 0.373; uninvolved: P < 0.001, R2 = 0.557) and ankle dorsiflexion angle (involved: P = 0.035, R2 = 0.214; uninvolved: P < 0.001, R2 = 0.554). The anterior-posterior center of pressure and ankle dorsiflexion angle significantly predicted the knee extensor moment in the involved limb in multivariate regression analysis (P = 0.006, model R2 = 0.429).

INTERPRETATION: The knee extensor moment was associated with the anterior-posterior center of pressure, knee flexion angle, and ankle dorsiflexion angle. Evaluating these parameters may enhance our understanding of the knee extensor moment during single-leg squatting after anterior cruciate ligament reconstruction in a clinical setting.