Bilateral Gait Six and Twelve Months Post-ACL Reconstruction Compared to Controls.

PURPOSE To compare gait biomechanics throughout stance phase 6 and 12 months following unilateral anterior cruciate ligament reconstruction (ACLR) between ACLR and contralateral limbs and compared to controls. METHODS Vertical ground reaction force (vGRF), knee flexion angle (KFA), and internal knee extension moment (KEM) were collected bilaterally 6 and 12 months post-ACLR in 30 individuals (50% female, 22±3 years, body mass index [BMI]=23.8±2.2kg/m) and at a single time point in 30 matched uninjured controls (50% female, 22±4 years, BMI=23.6±2.1kg/m). Functional analyses of variance were used to evaluate the effects of limb (ACLR, contralateral, and control) and time (6 and 12 months) on biomechanical outcomes throughout stance. RESULTS Compared to the uninjured controls, the ACLR group demonstrated bilaterally lesser vGRF (ACLR=9%BW, contralateral=4%BW) during early stance and greater vGRF during mid-stance (ACLR=5%BW, contralateral=4%BW) 6 months post-ACLR. Compared to the uninjured controls, the ACLR group demonstrated bilaterally lesser vGRF (ACLR=10%BW, contralateral=8%BW) during early stance and greater vGRF during mid-stance (ACLR=5%BW, contralateral=5%BW) 12 months post-ACLR. Compared to controls, the ACLR limb demonstrated lesser KFA during early stance at 6 (2.3°) and 12 months post-ACLR (2.0°), and the contralateral limb demonstrated lesser KFA during early stance at 12 months post-ACLR (2.8°). Compared to controls, the ACLR limb demonstrated lesser KEM during early stance at both 6 (0.011BW*height) and 12 months (0.007BW*height) post-ACLR, and the contralateral limb demonstrated lesser KEM during early stance only at 12 months (0.006BW*height). CONCLUSION Walking biomechanics are altered bilaterally following ACLR. During the first 12 months post-ACLR, both the ACLR and contralateral limbs demonstrate biomechanical differences compared to control limbs. Differences between the contralateral and control limbs increase from 6 to 12 months post-ACLR. Key Terms: Vertical ground reaction force, knee flexion angle, knee extension moment, walking biomechanics, anterior cruciate ligament.