Kinetic Interlimb Asymmetries in Loading and Propulsion During Walking From 2 to 8 Months After Anterior Cruciate Ligament Reconstruction

Normalization of walking is a rehabilitation goal after anterior cruciate ligament reconstruction (ACLR). However, no consensus is currently established on the kinetic variables supporting rehabilitation. We examined interlimb loading asymmetries and deviations from controls from 2 to 8 months post-ACLR at two different speeds. Ground reaction force of 14 patients with ACLR (23.9 years, 7 females) were assessed at 2-, 4-, 6-, and 8-months post-surgery while walking on instrumented treadmill at 5 and 6 km/h. Gait cycle characteristics, including stance phase durations, peak force, center-of-mass displacement and total power, were compared at each time point with matched controls (t-tests) and between involved and uninvolved limbs (mixed linear model). We observed that kinetic asymmetries were largest at 2 months and most persisted up to 8 months post-ACLR. An unloading strategy was observed on the involved limb, especially at 6 km/h, concerning the loading peak force (-6.6% at 4 months), the braking peak force (-9% at 6 months), the power absorption (-15.7% at 8 months) and the single support duration (-1.8% at 6 months compared to controls). These findings indicate that walking recovery after ACLR is characterized by unloading of the involved limb especially during the loading response and a compensation from the uninvolved limb throughout the stance, lasting up to 8 months when walking at 5 and 6 km/h. Walking at higher, controlled walking speeds should be assessed and retrained early after ACLR to identify and reduce residual loading asymmetries.