Decreased Knee Joint Contribution To Lower-limb Joint Energetics During Gait Following Anterior Cruciate Ligament Reconstruction

PURPOSE: Individuals with anterior cruciate ligament reconstruction (ACLR) exhibit altered knee kinematics and kinetics during gait that are linked to knee osteoarthritis (OA) development. Lower extremity joint energetics are important for understanding energy dissipation and generation at the joint and also influence OA-related joint tissue changes. However, the effects of ACLR on lower extremity joint energetics during walking remain uncertain. Therefore, this study sought to determine between-limb joint energetics differences during walking in individuals 6 months post-ACLR. METHODS: We conducted a cross-sectional analysis on 54 participants with primary unilateral ACLR (age: 22±5 yrs; mass: 73.8±13.3 kg; height: 1.7±0.1 m). They completed a 3-dimensional motion capture assessment of overground walking at their habitual speed. Ankle, knee, and hip joint works were calculated as the time integral of the negative (energy dissipation) or positive (energy generation) regions of their respective joint power curves during the stance phase of gait. The joint-specific contribution was calculated relative to the total (ankle+knee+hip) energy dissipation and generation and reported as a percentage. Dependent t-tests were used to compare joint energetics between limbs (P <0.05). RESULTS: Compared to the uninjured limb, the ACLR limb exhibited significantly lesser total energy dissipation (0.41±0.15 vs. 0.50±0.18 J/kg; p=0.01) and knee contribution to total energy dissipation (15.89±6.57 vs. 23.40±8.55%; p<0.0001). No significant difference in total energy generation (0.53±0.19 vs. 0.57±0.19 J/kg; p=0.31) was found between limbs, but the knee of the ACLR limb demonstrated a lesser contribution to total energy generation (16.15±5.91 vs. 19.91±6.02%; p=0.001) compared to the uninjured limb. CONCLUSIONS: Individuals with ACLR demonstrated a smaller contribution from the knee joint to the total work performed by the ACLR limb compared to the uninjured limb during walking, which may be attributed to changes in joint kinematics (i.e. decreased knee flexion angle) that the literature has consistently reported. Future work may seek to determine whether these changes are associated with OA-related joint tissue changes. Arthritis Foundation