Gait Biomechanics at Different Time Periods Following Anterior Cruciate Ligament Reconstruction

Abstract

Aberrant gait biomechanics following anterior cruciate ligament reconstruction (ACLR) are hypothesized to contribute to the increased risk of developing knee osteoarthritis (OA). It remains unclear how time since ACLR influences gait biomechanics. PURPOSE: To determine how time since ACLR influences loading characteristics during walking gait following ACLR. METHODS: Ninety-five (64 F, 31 M; 73.4±11.5 kg) individuals at least 6 months removed from unilateral ACLR and 25 (20 females, 5 males; 62.8±11.0 kg) uninjured controls volunteered for the study. The ACLR cohort was categorized into four groups based on time since ACLR: 6 months (n=24); 7-12 months (n=24); 13-36 months (n=21); >36 months (n=26). Kinetics and kinematics were sampled during walking gait at a self-selected speed with peak vertical ground reaction force magnitude (vGRF), peak instantaneous loading rate (ILR; first time derivative), and linear loading rate (LLR; slope), and peak internal knee extension, valgus, and varus moments identified during the first 50% of the stance phase. vGRF, ILR, and LLR were normalized to body weight (xBW) and moments were normalized to the product of BW and height (BW*ht). Outcomes were compared between groups via one-way ANOVA with Bonferroni corrections. RESULTS: vGRF was significantly lower in the 6 month (1.04±0.07 xBW) group compared to the uninjured (1.12±0.09 xBW; p=0.03) and 13-36 month (1.13±0.10 xBW; p=0.005) groups. LLR was significantly less in the 6 month (6.88±1.5 xBW/s) group compared to the 13-36 (9.02±2.0 xBW/s; p=0.005) and >36 month (8.57±2.2 xBW/s; p=0.038) groups. The internal knee extension moment was significantly larger in the 7-12 (-0.059±0.02 xBW*ht; p=0.006) and >36 month (-0.057±0.02 xBW*ht; p=0.01) groups compared to the uninjured group (-0.038±0.015 xBW*ht). CONCLUSION: Based on these results, walking gait biomechanics fluctuate following ACLR as representative of lower loading early and increasing over time. Continued research should be conducted to determine the necessary ranges for joint loading during walking gait to preserve joint health following injury and take into consideration the changes in walking gait over time to establish how these alterations influence risk of OA.