Bilateral Gait Differs From Controls Preoperatively To 4 Months Following Anterior Cruciate Ligament Reconstruction

There is a significant lack of evidence evaluating gait biomechanics linked to knee osteoarthritis, such as lesser peak vertical ground reaction force (vGRF) and knee flexion, prior to 6 months post-anterior cruciate ligament reconstruction (ACLR), a time when patients are most commonly engaging in formal rehabilitation. Purpose: To compare vGRF and knee flexion angle (KFA) during gait in individuals with unilateral primary ACL injury preoperatively (preop) as well as at 2 and 4 months post-ACLR with uninjured controls. Methods: Gait biomechanics were collected over ground at habitual walking speed in individuals with ACLR (n=55, age=21.3±4.7 yrs, BMI=24.4±3.5 kg/m2, 55% female) at preop, 2, and 4 months post-ACLR. Uninjured controls (n=51, age=21.4±4.2 yrs, BMI=24.1±2.6 kg/m2, 60% female) completed a single assessment. vGRF and KFA were calculated during the stance phase and functional waveform analyses were used to compare vGRF and KFA at each timepoint post-ACLR between 1) the ACLR limb and controls and 2) the uninvolved limb and controls. Results: The ACLR limb demonstrated lesser vGRF during early and late stance, and greater vGRF at midstance at preop (5-30% stance phase, 38-64%, 73-92%), 2 (5-31%, 39-64%, 73-93%), and 4 months (6-31%, 42-64%, 75-93%) post-ACLR compared with controls. The ACLR limb demonstrated greater KFA at heel strike and mid- to late stance at preop (1-8%, 36-97%), and lesser KFA during early stance and greater KFA during mid- and late stance at 2 (1-41%, 52-85%) and 4 months (1-42%, 54-86%) post-ACLR compared with controls. The uninvolved limb demonstrated lesser vGRF during early and greater vGRF during midstance at preop (22-32%, 42-65%), 2 (20-32%, 43-61%), and 4 months (20-28%, 46-59%) post-ACLR as well as lesser KFA within the first half of stance at preop (1-9%, 16-36%), 2 (1-52%), and 4 months (1-41%) post-ACLR compared with controls. Conclusion: Individuals with ACLR demonstrate less dynamic vGRF (i.e., lesser peak and greater midstance vGRF) and stiffer KFA (i.e., lesser early stance peak and greater midstance KFA) bilaterally compared to uninjured controls at preop and early post-ACLR timepoints. These gait biomechanics may lead to more sustained and localized loading on the tibiofemoral cartilage and thus support the need for early targeted bilateral gait rehabilitation. This work was funded by the Arthritis Foundation