Pain Early After Anterior Cruciate Ligament Reconstruction is Associated With 6-Month Loading Mechanics During Running

Abstract

Background: Anterior cruciate ligament reconstruction (ACLR) results in persistent altered knee biomechanics, but contributing factors such as pain or patient function, leading to the altered loading, are unknown. Hypothesis: Individuals with worse self-reported pain after ACLR would have poorer biomechanics during running, and poor loading mechanics would be present in the ACLR limb compared with contralateral and control limbs. Study Design: Cohort pilot study. Level of Evidence: Level 3. Methods: A total of 20 patients after ACLR (age, 18.4 ± 2.7 years; height, 1.7 ± 0.1 m; mass, 84.2 ± 19.4 kg) completed visual analog scale and Knee Injury and Osteoarthritis Outcomes Score (KOOS) at 1 and 6 months postsurgery. At 6 months postsurgery, patients underwent biomechanical testing during running. A total of 20 control individuals also completed running biomechanical analyses. Associations between patient outcomes and biomechanics were conducted, and differences in running biomechanics between groups were analyzed. Results: KOOS pain score 1 month after surgery was associated with peak ACLR knee abduction moment ( R2 = 0.35; P = 0.01). At 6-months, KOOS sport score was related to peak abduction moment in the ACLR limb ( R2 = 0.23; P = 0.05). For change scores, the improvement in pain scores related to ACLR limb peak knee abduction moment ( R2 = 0.55; P = 0.001). The ACLR limb had lower knee excursion, extension moments, and ground-reaction forces compared with the uninvolved and control limb. The uninvolved limb also had higher ground-reaction forces compared with the ACLR limb and control limb. Conclusion: These results suggest that patient-reported outcomes 1 and 6 months after surgery are associated with running mechanics 6 months after ACLR. Further, the underloading present in the ACLR limb and overloading in the uninvolved limb indicates greater need for running rehabilitation after ACLR. Clinical Relevance: Understanding pain and how it may be linked to movement dysfunction is important for improving long-term outcomes.