Hip and Knee Kinematics and Kinetics During Landing Tasks After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-Analysis

Objective: To evaluate the current evidence concerning kinematic and kinetic strategies adopted during dynamic landing tasks by patients with anterior cruciate ligament reconstruction (ACLR). Data Sources: PubMed, Web of Science. Study Selection: Original research articles that evaluated kinematics or kinetics (or both) during a landing task in those with a history of ACLR were included. Data Extraction: Methodologic quality was assessed using the modified Downs and Black checklist. Means and standard deviations for knee or hip (or both) kinematics and kinetics were used to calculate Cohen d effect sizes and corresponding 95% confidence intervals between the injured limb of ACLR participants and contralateral or healthy matched limbs. Data were further stratified by landing tasks, either double-or singlelimb landing. A random-effects-model meta-analysis was used to calculate pooled effect sizes and 95% confidence intervals. Data Synthesis: The involved limbs of ACLR patients demonstrated clinically and significantly lower knee-extension moments during double-legged landing compared with healthy contralateral limbs and healthy control limbs (Cohen d range = -0.81 to -1.23) and decreased vertical ground reaction forces when compared with healthy controls, regardless of task (Cohen d range = -0.39 to -1.75). Conclusions: During single-and double-legged landing tasks, individuals with ACLR demonstrated meaningful reductions in injured-limb knee-extension moments and vertical ground reaction forces. These findings indicate potential unloading of the injured limb after ACLR, which may have significant implications for secondary ACL injury and long-term joint health.