JOA - 2026-05-19 - Journal Article
Task-Specific Electromyographic Changes in Gastrocnemius Medialis and Tibialis Anterior Muscles after Total Knee Arthroplasty.
Shetty S, Vijayan S, Rao Kg M, Marpalli S, George BM
Topics
Key Takeaway
GM and TA activation during gait remained significantly below healthy controls at 12 months post-TKA (GM: P<0.001; TA: P=0.01), with higher GM activation strongly associated with reduced pain and improved function.
Summary Depth
Choose how much analysis to show on this article page.
Summary
This prospective longitudinal study measured wireless EMG RMS amplitudes of GM and TA in 77 severe knee OA patients undergoing TKA versus 77 age- and sex-matched controls across five time points. Pre-TKA, GM and TA activation during gait was significantly reduced versus controls (P<0.001), while differences during knee extension and sit-to-stand were minimal. Post-TKA improvements were gradual and non-significant across tasks, with persistent gait deficits at 12 months and a strong association between GM activation and pain/functional outcomes.
Key Limitation
Post-TKA improvements were non-significant across all tasks, yet no rehabilitation protocol was standardized or reported, preventing any conclusion about whether targeted distal muscle training would alter these trajectories.
Original Abstract
BACKGROUND
Knee osteoarthritis (OA) causes pain, altered joint mechanics, and muscle dysfunction, often requiring total knee arthroplasty (TKA). Although quadriceps and hamstring muscle deficits after TKA are well-documented, neuromuscular adaptations of distal leg muscles remain underexplored. The gastrocnemius medialis (GM) and tibialis anterior (TA) muscles are key for dynamic stability, propulsion, and gait. Understanding their activation following TKA is vital for optimizing rehabilitation. This study evaluated task-specific electromyographic (EMG) changes in GM and TA before and after TKA and their associations with clinical outcomes post-TKA.
METHODS
A prospective, longitudinal single-center study was conducted on 77 individuals who had severe knee OA scheduled for TKA and 77 age- and sex-matched healthy controls. Muscle activity of the GM and TA was recorded using a wireless EMG system. The EMG root mean square (RMS) amplitudes were measured preoperatively and at six weeks, three, six, and 12 months postoperatively. Pain and functional outcomes were measured using relevant clinical tools.
RESULTS
Pre-TKA, both GM and TA exhibited significantly reduced activation during gait compared to controls (P < 0.001), with minimal differences during knee extension and sit-to-stand. Post-TKA, gradual, but non-significant improvements were noted across all tasks, with the greatest increases at six to 12 months. Despite recovery, GM and TA activation during gait remained significantly lower than controls at 12 months (GM: P < 0.001; TA: P = 0.01). Higher gastrocnemius medialis muscle activation during gait was strongly linked to reduced pain and improved functional outcomes at 12 months post-TKA.
CONCLUSION
Although TKA and standard rehabilitation improve distal leg muscle activation over time, gastrocnemius medialis and tibialis muscle anterior function remain suboptimal even after one year. Persistent deficits in distal neuromuscular control may contribute to residual gait abnormalities post-TKA, highlighting the need for task-specific and distal muscle-focused rehabilitation interventions.