Comparison of gait characteristics at different postoperative phases following anterior cruciate ligament reconstruction

To characterize gait characteristics at different phases after anterior cruciate ligament (ACL) reconstruction and inform rehabilitation assessment. This cross-sectional study enrolled 100 patients following unilateral ACL reconstruction with autologous hamstring tendon grafts, stratified into five postoperative phases (n = 20 each): Group A (1.5–3 months), Group B (3–6 months), Group C (6–9 months), Group D (9–12 months), and Group E (≥ 12 months). Twenty age- and sex-matched healthy volunteers constituted the control group (Group F). Spatiotemporal parameters, gait cycle phases, center of pressure trajectory, and plantar pressure distribution were measured using the Zebris FDM-T system. Interlimb and intergroup statistical comparisons were conducted using appropriate parametric and non-parametric tests as indicated by data distribution. (1) On the involved side, Group A demonstrated significantly reduced step length, stride length, and gait velocity compared to all other groups, whereas Group E showed no significant differences relative to controls. Step width in Group A was significantly greater than in Groups C–F. (2) Significant interlimb asymmetry was observed in Groups A–C but not in Groups D–E. In Group A, loading response and double support phases were prolonged, whereas the mid-stance phase was shortened. Group E demonstrated no significant differences compared to controls. (3) On the involved side, gait line length and single support line length were significantly shorter compared to the uninvolved side across Groups A–E. Group A exhibited significantly shorter parameter values and greater mediolateral displacement compared to Groups C–F. COP trajectory parameters in Group E showed substantially attenuated differences relative to controls. (4) Rearfoot pressure on the involved side was significantly lower than on the uninvolved side across Groups A–E. All regional plantar pressure measurements in Group A were significantly reduced compared to Groups C–F. Conversely, Group E exhibited plantar pressure profiles equivalent to controls. Gait characteristics after ACL reconstruction peak at 1.5–3 months and largely normalize by 12 months, though COP trajectory and rearfoot pressure asymmetry persist, informing clinical assessment of postoperative recovery. Chinese Clinical Trial Registry ChiCTR2400087325. Registered on 25/07/2024.