Does Normalizing Walking Speed Normalize Gait Biomechanics In Patients With Anterior Cruciate Ligament Reconstruction?

Aberrant gait biomechanics (i.e., smaller vertical ground reaction force [vGRF] peaks, greater midstance vGRF, and smaller peak knee flexion angle [KFA]) in individuals with anterior cruciate ligament reconstruction (ACLR) are linked to posttraumatic osteoarthritis (PTOA) development and have led to the advancement of novel gait retraining interventions. ACLR individuals walk slower than uninjured controls and slower walking speeds are associated with these aberrant gait biomechanics. Yet, it is not clear if increasing walking speed will normalize gait biomechanics post-ACLR that are linked to PTOA. PURPOSE: To determine the effect of acutely increasing habitual walking speed in individuals 6 months post-ACLR to the speed of uninjured controls on vGRF and KFA in comparison to uninjured controls. METHODS: 3D gait biomechanics were collected at each ACLR participant’s habitual walking speed and at a previously published predetermined normal speed of 1.3 m/s from uninjured controls. Gait biomechanics were also collected on matched uninjured controls at their habitual speed. Functional waveform analyses were used to compare biomechanics (vGRF and KFA) during the stance phase between 1) ACLR habitual speed vs ACLR predetermined normal speed (1.3 m/s) and 2) ACLR predetermined normal speed (1.3 m/s) vs matched controls. RESULTS: 30 ACLR participants (20 females, age: 22 ± 4 years, BMI: 24.0 ± 3.0 kg/m2) and 30 age, BMI, and sex matched controls (age: 22 ± 4 years, BMI: 23.6 ± 2.5 kg/m2) participated. Compared to habitual speed (1.18 ± 0.21 m/s), the predetermined normal speed elicited increases in vGRF and KFA during early stance (vGRF: 6-22%; KFA: 16-30%) in the ACLR group. Compared to controls (habitual speed: 1.34 ± 0.21 m/s), the ACLR group at the predetermined normal speed exhibited smaller vGRF in early and late stance (9-32, 74-95%), greater midstance vGRF (41-66%), smaller KFA during early and midstance (1-48%), and greater KFA in late stance (58-83%). CONCLUSION: Increasing walking speed to a predetermined normal speed elicited more dynamic vGRF profiles and greater KFA excursion, which are associated with better cartilage and symptom-related PTOA outcomes post-ACLR. Yet, ACLR gait biomechanics at the predetermined normal speed continue to remain different than controls. Funded by the Arthritis Foundation.