Intraarticular corticosteroid injection into rheumatoid arthritis knees improves extensor muscles strength.

Eleven arthritic knee joints in seven patients with rheumatoid arthritis were studied before and after intraarticular injection of a corticosteroid preparation. Extensor muscle torque and quantitative electromyography increased on days 7 and 14 after treatment, indicating that muscle function had been inhibited by synovitis. Clinical signs of synovitis, such as pain, range of motion and knee circumference, also improved. Synovial fluid withdrawal alone improved extensor muscle torque. Joints with instability and/or radiological cartilage involvement also improved.