Time-Dependent Alterations in Walking Biomechanics After Anterior Cruciate Ligament Reconstruction Compared with Healthy Individuals: A Systematic Review with Meta-analysis

BACKGROUND: Knee injuries involving the anterior cruciate ligament (ACL) are often treated through surgical care to restore knee joint stability. Despite surgical treatment, there is evidence of altered biomechanical gait characteristics for short-, mid-, and even long-term post ACL reconstruction (ACLR). OBJECTIVE: In this systematic review with meta-analysis, we aimed to analyze lower extremity joint kinematics and kinetics recorded during walking in individuals with ACLR and determine the time course of recovery of gait biomechanics following ACLR. METHODS: Five electronic databases (Scopus, PubMed, EMBASE, Physiotherapy Evidence Database (PEDro), Cochrane Central Register of Controlled Trials [CENTRAL]) were systematically searched for articles potentially eligible for inclusion from inception until January 2026. A PECOS (Participants: ACLR individuals aged ≥ 18; Exposure: ACL surgery; Comparators: healthy controls; Outcomes: lower limb kinematics and kinetics during the walking stance phase; and Study design: case control studies, case series, cross-sectional studies, randomized controlled trials [baseline], cohort studies) approach was applied to define inclusion and exclusion criteria. Using cross-sectional studies, gait biomechanics were assessed short- (0-<6 months), mid- (≥ 6-12 months), and long-term (≥ 12 months) post-surgery in ACLR patients versus healthy controls. Gait biomechanics assessed during the stance phase were extracted from the included articles. Between-group standardized mean differences (SMD) with 95% confidence intervals (CI) were computed using a random-effects model to elucidate the gait biomechanical differences between ACLR patients and healthy controls. The modified version of the Downs and Black checklist was used to assess the methodological quality of the included studies. RESULTS: = 69%) were lower in the ACLR group compared to controls. CONCLUSIONS: After ACLR, the observed reduction in peak knee flexion angle suggests a walking pattern with a straighter knee, or a less erect gait posture, which can persist for ≥ 12 months post surgery. The lower sagittal plane knee moments suggest a less dynamic gait, characterized by reduced muscular demand. The small deviations in gait biomechanics from normal are lasting but inconsistent between studies. While associated with long-term outcomes like post-traumatic osteoarthritis, the direct clinical relevance of these specific gait changes requires further study.