Aberrant Gait Biomechanics Are Not Associated with Aberrant Landing Biomechanics in Those with ACL Reconstruction

Abstract

High knee joint loading during walking gait and jump-landing (JL) may influence the development of post-traumatic osteoarthritis (PTOA) and increase the risk of a second anterior cruciate ligament (ACL) injury, respectively, following anterior cruciate ligament reconstruction (ACLR). It remains unknown if individuals who demonstrate higher lower extremity loading during walking gait also demonstrate higher loading during JL. PURPOSE: To determine associations between peak vertical ground reaction force (vGRF) and vGRF instantaneous loading rate during walking gait and JL in individuals with an ACLR. Secondarily, we sought to determine if limb symmetry indices (LSI = ACLR limb/uninvolved limb) for the kinetics variables associated between the gait and JL tasks. METHODS: Thirty-five individuals (74% female, 45.5±38 months post-ACLR, 22.1±3.4 years old, 169.4±10.8 cm, 73.4±17.9kg) with a unilateral ACLR were recruited for this cross-sectional study. Participants performed 5-trials of self-selected walking gait (over 6m walkway) and JL (30 cm box placed 50% of height from force plates), respectively. Kinetics were extracted from the first 50% of the stance phase of walking gait and the first 100ms of landing for JL. Pearson product-moment (r) and Spearman’s Rho (ρ) analyses were used to determine associations between the same outcome measures collected during walking gait and JL. Significance was set a priori at P≤ 0.05. RESULTS: Greater vGRF instantaneous loading rate during gait (51.27±12.56% bodyweight per second (BW/s)) associated with greater vGRF instantaneous loading rate during JL (180.12±119.27 BW/s; ρ=0.389, P=0.021) in the uninvolved limb. All other associations between walking gait and JL kinetics and LSI were negligible (range ρ= -0.289 to 0.209) and non-significant. CONCLUSION: No systematic associations were found between gait and JL kinetics for either limb or LSI’s in people with unilateral ACLR. Individuals who demonstrate high or low loading during dynamic activities may not be the same people that demonstrate high or low magnitude loading during gait. Therefore, individuals who may be at risk for PTOA onset, due to aberrant repetitive lower extremity loading, may not be the same people who are at risk for a second ACL injury, which is more likely to occur during a dynamic movement.