Anterior cruciate ligament reconstruction in adolescent patients: limb asymmetry and functional knee bracing.

Abstract

Anterior cruciate ligament (ACL) reinjury rates are high in adolescent patients. Knee braces are commonly used after ACL reconstruction to prevent reinjury during return to sports. Adolescent patients following ACL injury would demonstrate a decreased vertical ground-reaction force, knee extension moment, knee flexion angle, and knee flexion velocity on the surgical limb when compared with the nonsurgical limb during a side-cutting task. A functional knee extension-resistant brace would decrease the limb asymmetries. Controlled laboratory study. Twenty-three adolescent patients 6 months after ACL reconstruction were recruited for this study. Three-dimensional kinematic and kinetic data were collected bilaterally (surgical, nonsurgical) during a 35° side-cutting task while the patient was wearing and not wearing a functional knee extension-resistant brace (nonbraced, braced) on the surgical limb. The surgical limb demonstrated a significant decrease in peak impact vertical ground-reaction force (2.55 body weight [BW] vs 2.8 BW; P < .01), peak propulsion vertical ground-reaction force (2.15 BW vs 2.3 BW; P < .01), peak knee extension moment (0.13 BW × body height [BH] vs 0.17 BW × BH; P < .01), knee flexion angle at peak knee flexion velocity (27.8° vs 30.0°; P = .01), peak knee flexion angle (44.1° vs 48.5°; P < .01), and peak knee flexion velocity (571.3 deg/sec vs 640.1 deg/sec; P < .01) when compared with the nonsurgical limb during both nonbraced and braced conditions. Bracing increased the initial knee flexion velocity (42.4 deg/sec vs -40.2 deg/sec; P = .01) and decreased the initial knee flexion angle on the surgical limb (13.1° vs 15.7°; P < .01). Bracing also affected kinematics of the nonsurgical limb. Bracing did not decrease the asymmetry between surgical and nonsurgical limbs. Adolescent patients 6 months after ACL reconstruction demonstrated significant kinematic and kinetic asymmetries between the surgical and nonsurgical limbs. The limb asymmetries persisted when the patients were wearing a functional knee brace. There were changes in the surgical knee kinematics with and without bracing, especially near initial ground contact. The limb asymmetries are of concern with regard to injuring the graft or the contralateral limb when the patients return to sport.