High muscle co‐contraction does not result in high joint forces during gait in anterior cruciate ligament deficient knees. Issue 1 (9th October 2018)

• Record Type: Journal Article
• Authors: Khandha, Ashutosh; Manal, Kurt; Capin, Jacob; Wellsandt, Elizabeth; Marmon, Adam; Snyder‐Mackler, Lynn; Buchanan, Thomas S.
• Is Part Of: Journal of orthopaedic research. Volume 37:Issue 1(2019)
• Page Start: 104
• Page End: 112
• Publication Date: 2018-10-09
• Subjects: knee -- muscle co‐contraction -- joint forces -- musculoskeletal modeling -- ACL; Orthopedics -- Periodicals; Musculoskeletal system -- Periodicals; 616.7
• DOI: 10.1002/jor.24141
• Languages: English
• ISSNs: 0736-0266

Abstract

ABSTRACT: The mechanism of knee osteoarthritis development after anterior cruciate ligament injuries is poorly understood. The objective of this study was to evaluate knee gait variables, muscle co‐contraction indices and knee joint loading in young subjects with anterior cruciate ligament deficiency (ACLD, n = 36), versus control subjects ( n = 12). A validated, electromyography‐informed model was used to estimate joint loading. For the involved limb of ACLD subjects versus control, muscle co‐contraction indices were higher for the medial ( p = 0.018, effect size = 0.93) and lateral ( p = 0.028, effect size = 0.83) agonist–antagonist muscle pairs. Despite higher muscle co‐contraction, medial compartment contact force was lower for the involved limb, compared to both the uninvolved limb (mean difference = 0.39 body weight, p = 0.009, effect size = 0.70) as well as the control limb (mean difference = 0.57 body weight, p = 0.007, effect size = 1.14). Similar observations were made for total contact force. For involved versus uninvolved limb, the ACLD group demonstrated lower vertical ground reaction force (mean difference = 0.08 body weight, p = 0.010, effect size = 0.70) and knee flexion moment (mean difference = 1.32% body weight * height, p = 0.003, effect size = 0.76), during weight acceptance. These results indicate that high muscle co‐contraction does not always result in high knee joint loading, which is thought to be associated with knee osteoarthritis. Long‐term follow‐up is required to evaluate how gait alterations progress in non‐osteoarthritic versus osteoarthritic subjects. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res Abstract : The objective of this study was to evaluate knee gait variables, muscle co‐contraction indices, and knee joint loading in young subjects with anterior cruciate ligament deficiency (ACLD). We used a validated, electromyography‐informed model to estimate knee joint loading. While ACLD subjects compensate for loss in knee joint stability by increasing muscle co‐contraction, simultaneously, they also step more "lightly" (i.e., lower vertical ground reaction force) on their involved limb. These combined strategies lead to smaller, rather than greater knee joint loading.