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.