Synovial Chondromatosis of the Knee

Introduction

Synovial chondromatosis is a rare condition where the lining of a joint (the synovium) produces small, cartilage-like nodules. Over time, these nodules can break off and float inside the joint, forming loose bodies. The knee is the most commonly affected joint. When synovial chondromatosis occurs in the knee, people may notice pain, swelling, stiffness, or a catching sensation when moving the joint. Sometimes, the knee may even lock temporarily if a loose piece gets stuck.

Symptoms

In the knee, synovial chondromatosis can lead to symptoms that feel similar to arthritis. The loose bodies inside the joint can irritate the cartilage and cause ongoing inflammation. This can make everyday activities like walking, bending, or climbing stairs uncomfortable. Some patients also experience a gradual loss of motion in the knee. If the condition goes untreated for a long time, it may damage the joint surface and contribute to the development of arthritis.

How Synovial Chondromatosis of the Knee is Diagnosed

To diagnose synovial chondromatosis in the knee, a doctor will ask about symptoms such as pain, stiffness, and mechanical problems like catching or locking. During the physical exam, the doctor may feel or hear grinding or clicking within the knee. Imaging studies are very important. X-rays can sometimes show calcified loose bodies, while MRI scans give a clearer picture of the synovium and the extent of the condition. These tests help confirm the diagnosis and rule out other possible knee problems.

Treatment of Synovial Chondromatosis of the Knee

Treatment of synovial chondromatosis affecting the knee usually depends on the severity of symptoms. For mild cases, rest, anti-inflammatory medications, and activity modification may help. However, many patients need surgery, especially if there are loose bodies causing mechanical problems or significant pain. Surgery typically involves removing the loose bodies and sometimes part of the abnormal synovium (synovectomy) to reduce the chance of recurrence. This surgery can often be performed arthroscopically. The prognosis is generally good after surgery, though in some cases the condition can come back. Long-term, if the knee joint has been damaged, patients may develop arthritis, but early treatment can lower this risk.

Edited by Stephen Pinney MD, September 19th 2025.