Synovium is a thin layer of tissue that lines your joints and tendon sheaths. It protects and lubricates the surfaces. Irritated or inflamed synovium is called synovitis.
Inflammatory arthritis such as rheumatoid arthritis is a common form of synovitis. Treatment may include resting and icing the joint, prescription anti-inflammatory medication or injections into the joint to reduce swelling. In some cases surgery may be necessary.