Joint-specific mechanical work during overground running in athletes with anterior cruciate ligament reconstruction...

Individuals with anterior cruciate ligament reconstruction (ACLR) history show altered running mechanics. Mechanical work analysis is useful for identifying compensatory strategies. Negative work represents energy absorption and positive work represents energy generation. The purpose of this study was to quantify and compare the mechanical work distribution across the hip, knee, and ankle joints during running in individuals with ACLR, uninvolved limb, and healthy control group.

Twenty-two male recreational athletes with unilateral ACLR and 22 healthy-male controls ran overground at 3.3 m/s. We used 3-Dimensional motion-capture and force-plate data to calculate positive and negative mechanical work and the relative contributions of the ankle, knee, and hip joints during stance-phase of running. A mixed-design ANOVA followed by univariate ANOVAs was used to assess the effects of ACLR on the outcomes.

ACLR limb demonstrated significantly less negative and positive work at the knee compared to the uninvolved and control limbs (p_holm < 0.05). This deficit was compensated for by significantly greater negative work at the hip (p_holm = 0.018 vs. uninvolved) and significantly greater positive work at the ankle (p_holm < 0.001 vs. uninvolved;p_holm = 0.005 vs. control).

The relative contributions of the joints to total work reflected these changes, showing a shift in mechanical load away from the knee and onto the hip and ankle. Individuals with a history of ACLR exhibit significant redistribution of mechanical work during running, characterized by a knee-unloading strategy compensated for by increased hip absorption and ankle propulsion. This pattern highlights the need for whole-limb function-based rehabilitation that extends beyond isolated-knee recovery.