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Task-Specific Electromyographic Changes in Gastrocnemius Medialis and Tibialis Anterior Muscles After Total Knee
Saidan Shetty1, Sandeep Vijayan2, Mohandas Rao Kg3
1Department of Anatomy, Melaka Manipal Medical College - Manipal Campus, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India.
Background:
Knee osteoarthritis 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 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 osteoarthritis scheduled for TKA and 77 age- and sex-matched healthy controls. Muscle activity of the GM and TA was recorded using a wireless electromyography (EMG) system. The EMG root mean square 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 nonsignificant 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 GM muscle activation during gait was strongly linked to reduced pain and improved functional outcomes at 12 months post-TKA.
Conclusions:
Although TKA and standard rehabilitation improve distal leg muscle activation over time, GM 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.
