Musculoskeletal Ultrasound with Elastography in the Evaluation of Muscle State in Rheumatoid Arthritis Patients

Rheumatoid arthritis is a chronic debilitating disease. Muscle weakness is a common symptom in patients with rheumatoid arthritis (RA). From a metabolic perspective, muscle mass is determined by the balance between protein synthesis and degradation. People with RA note tenderness, stiffness, and pain in affected muscles.

In RA, chronic inflammation is a primary driver of muscle weakness. Persistent synovitis leads to the release of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), which contribute to muscle atrophy and dysfunction. Joint damage and pain further limit physical activity, exacerbating muscle wasting through disuse atrophy. Additionally, the systemic inflammation associated with RA can lead to metabolic disturbances, including insulin resistance, which negatively impacts muscle protein synthesis and overall muscle health.

RA can cause a 25% to 70% reduction in muscular strength, typically caused by decreased skeletal muscle mass, ,Reduced muscle strength is usually considered to be a result of decreased muscle mass due to disuse atrophy. Rheumatoid cachexia, a term used in RA, is defined as a loss of skeletal muscle mass and with no, or little weight loss in fat mass Muscle weakness not only reduces the quality of life for the affected patients, but since patients' ability to work decreases it will also dramatically increase the burden on society (e.g. increased costs for long-term sick leave). Thus, RA severely affects both the individual and the society Given the complexity of muscle affection in RA , accurate assessment is essential for effective management. Conventional clinical methods, such as manual muscle testing and grip strength measurements, provide limited information on the underlying causes of muscle weakness. Advanced imaging techniques, such as conventional ultrasound (US) and shear wave elastography (SWE), offer a more comprehensive evaluation by providing detailed information on muscle morphology and stiffness.