Synovitis is a term given to a condition caused by the abnormal inflammation of the knee lining. This tissue is known as the synovium. While the exact cause of inflammation can vary, when it occurs, it can result in chronic pain, swelling, catching, or knee stiffness. Synovitis can affect one small, localized area (known as localized synovitis), or can spread throughout the knee joint and become more difficult to treat (known as diffuse synovitis). The knee joint lining can pinch between the leg and thigh bones.

Symptoms and Diagnosis

Symptoms of synovitis include knee pain, weakness, stiffness, or swelling. Knee locking, or a catching sensation, may also result. Your physician will conduct a comprehensive patient history and physical examination. It is difficult to diagnose synovitis through an X-ray; an MRI is usually needed and may show a thickening of the joint lining or other pathology.


Surgery is usually the best treatment option for patients with symptomatic synovitis, if non-surgical treatment has failed. Your physician will perform an arthroscopic surgery to remove the inflamed, scarred, or pinching portion of the lining, which is called synovectomy. Your physician will ensure that healthy joint lining will not be removed.


Following arthroscopic knee surgery, physical therapy will be prescribed to initiate range-of-motion and to restore strength and function to the knee. Physical therapy is important in the early days following surgery to prevent post-op stiffness. Most patients walk normally within 7 days and return to full activity in less than 4 weeks. Others with significant swelling may require a slower rehabilitation.