Walking Ground Reaction Force Post-ACL Reconstruction: Analysis of Time and Symptoms

PURPOSEThe association between lower-extremity loading and clinically relevant knee symptoms at different time points after anterior cruciate ligament reconstruction (ACLR) is unclear. Vertical ground reaction force (vGRF) from walking was compared between individuals with and without clinically relevant knee symptoms in three cohorts24 months post-ACLR. METHODSOne hundred twenty-eight individuals with unilateral ACLR were classified as symptomatic or asymptomatic, based on previously defined cutoff values for the Knee Osteoarthritis and Injury Outcome Score (24 months post-ACLR [symptomatic, n = 13; asymptomatic, n = 33]). Vertical ground reaction force exerted on the ACLR limb was collected during walking gait, and functional analyses of variance were used to evaluate the effects of symptoms and time post-ACLR on vGRF throughout stance phase (α = 0.05). RESULTSSymptomatic individuals, 24 months post-ACLR, exhibited greater vGRF during both peaks, but lesser vGRF during midstance, compared to asymptomatic individuals. CONCLUSIONRelative to asymptomatic individuals, symptomatic individuals are more likely to underload the ACLR limb early after ACLR (i.e., 24 months). We propose these differences in lower-extremity loading during walking might have implications for long-term knee health, and should be considered when designing therapeutic interventions for individuals with an ACLR.