Is Modular Control Related to Functional Outcomes in Individuals with Knee Osteoarthritis and Following Total Knee Arthroplasty?

Individuals who undergo total knee arthroplasty (TKA) for treatment of knee osteoarthritis often experience suboptimal outcomes. Investigation of neuromuscular control strategies in these individuals may reveal factors that contribute to these functional deficits. The purpose of this pilot study was to determine the relationship between patient function and modular control during gait before and after TKA. Electromyography data from 36 participants (38 knees) were collected from 8 lower extremity muscles on the TKA-involved limb during at least 5 over-ground walking trials before (n=30), 6-months after (n=26), and 24-months after (n=13) surgery. Muscle modules were estimated using non-negative matrix factorization. The number of modules was determined from 500 resampled trials for each participant. A higher number of modules was related to better performance-based and patient-reported functional measures before and 6-months after surgery. Participants were considered to have proper module organization if the composition of all modules was similar to healthy, age-matched controls. Participants with proper organization trended toward better function 24-months after surgery, though these results were not statistically significant. We also observed plasticity in the participants' modular control strategies, with 100% of participants who were present before and 24-months after surgery demonstrating changes in number of modules and/or the organization of at least 1 module. Our work suggests that functional improvements following TKA may initially present as increases in the number of modules recruited during gait. Once individuals can produce complex and discrete neuromuscular control patterns, further improvements may present as improved module organization. NEW & NOTEWORTHY This work is the first to characterize motor modules in TKA both before and after surgery and to demonstrate changes in the number and organization of motor modules over the time course of recovery, which may be related to changes in patient function. The plasticity of modular control in this population is a key finding which has not been previously documented and may be useful in predicting or improving surgical outcomes through novel rehabilitation protocols.