Running into deficits: Post‐operative bracing limits knee extension recovery 6 months after anterior cruciate ligament reconstruction

PURPOSE: To evaluate whether postoperative knee bracing impacts functional recovery following anterior cruciate ligament reconstruction (ACLR) using hamstring autografts, focusing on dynamic, continuous joint kinematics during gait, running and jumping tasks. METHODS: In this single-centre, randomised controlled trial, 114 patients undergoing isolated ACLR were assigned to a braced or brace-free rehabilitation protocol. Both groups followed the same standardised rehabilitation protocol, with the braced group using a rigid orthosis for 6 weeks postoperatively. Functional outcomes were assessed through 3D kinematic analysis using inertial measurement units during walking, running, countermovement jumps (CMJ) and drop jumps (DJ) at 6- and 12-month postoperatively. Statistical parametric mapping (SPM) was used to analyse time-continuous biomechanical data. RESULTS: At 6 months, the braced group demonstrated a significant deficit in knee extension during push-off (22.7%-34.5% of the running step, max effect size [ES] = -0.60, min ES = -0.69) and reduced ankle extension during the push-off phase of DJs (98.5%-99.9% of the loading phase, max ES = -0.55, min ES = -0.56). These deficits were of moderate to large ERs and exceeded standard error thresholds for clinical relevance. CONCLUSIONS: Postoperative bracing following ACLR delays early functional recovery by restricting sagittal knee and ankle joint motion. Brace-free rehabilitation protocols appear equally effective and better support restoration of normal joint mechanics. Early assessment and correction of range-of-motion deficits are critical, particularly before resuming running or demanding physical activities. LEVEL OF EVIDENCE: Level I.