Synovial Chondromatosis

Also known as: synovial osteochondromatosis, SOC.

What is synovial chondromatosis?

The synovial membrane is a thin layer of tissue that lines the part of a joint that acts as a shock absorber between joints of bones. When the synovium thickens and fragments break off, the pieces may grow, calcify (become bone-like nodules) and become loose in the joint. This is synovial chondromatosis. Usually this process is benign (non-cancerous), however rarely, SOC may be become malignant.

What causes synovial chondromatosis?

The cause of synovial chondromatosis is unknown.

What are the signs/ symptoms of synovial chondromatosis?

Common signs/symptoms include joint swelling (fluid in the joint), joint pain, difficulty with joint movement and a creaking or popping sensation during movement. Sometimes the nodules can be felt under the skin close to the joint.

What are synovial chondromatosis care options?

Depending on symptoms, observation may be all that is needed. Surgery may be considered to remove the thickened synovium and/or the loose bodies in the joint. 

Reviewed by: Jack Wolfsdorf, MD, FAAP

This page was last updated on: September 16, 2025 12:20 PM