People with synovial chondromatosis have noncancerous tumors that break off from tissue and move inside a joint. The tumors mostly affect your knees, hips or shoulders. Arthritis is one cause. Sometimes, the tumors damage a joint, causing osteoarthritis. Healthcare providers perform arthroscopic surgery to remove the tumors and improve range of motion.
Synovial chondromatosis is a rare condition where noncancerous (benign) tumors affect joints like your knee. The tumors develop in your synovium, the thin layer of tissue that lines your joints. Synovial chondromatosis can cause severe joint damage and osteoarthritis. If you already have arthritis, the condition can make the problem worse.
You may better understand this condition by defining the parts of each word:
You may also hear these terms:
Synovial chondromatosis is a rare type of benign bone tumor that grows outside the bone. Most people have multiple nodules or tumors in a single joint. The most common place for nodules to form is your knee. Nodules may also affect your elbow, hip or shoulder. In rare instances, the condition affects smaller joints in your ankle, wrist or jaw.
Synovial chondromatosis is rare, affecting approximately 1 in 100,000 people. It mostly occurs in people assigned male at birth (AMAB) who are between 30 and 50 years old.
There are two types of synovial chondromatosis:
When you have synovial chondromatosis, the synovium grows differently than it should. The tissue forms nodules (abnormal growths) of cartilage that may be as small as a grain of rice or as large as a marble. Some people have dozens of nodules of varying sizes.
These growths break off from your synovium tissue and enter your joint space. Synovial fluid in your joint surrounds the nodules, leading to calcification (hardening). In some instances, the nodules turn into a bone-like substance (ossify). As these hardened nodules move around, they damage the cartilage that protects your joint. You develop painful osteoarthritis when the damaged cartilage wears away, exposing your joint surface. If you have the secondary type, existing joint damage worsens.
You may also have:
Depending on the affected body part, you may have:
For diagnosis and treatment, you may see an orthopaedist. This medical doctor specializes in the treatment of musculoskeletal problems. Your healthcare provider will perform a physical examination and evaluate your symptoms.
These imaging tests aid the diagnosis. They also can show signs of osteoarthritis and fluid in your joint.
For secondary synovial chondromatosis, your healthcare provider may recommend holding off on major treatment. Nonsteroidal anti-inflammatory drugs (NSAIDs) and pain relievers can ease symptoms. You’ll get regular imaging tests to monitor your joint. You may need surgery to treat severe joint damage.
Surgery involves removing the tumors in addition to part or all of your affected synovium tissue (a synovectomy). After surgery, you may do physical therapy to regain range of motion and strengthen the joint.
The surgery is typically an arthroscopic procedure. Arthroscopy incisions are smaller and cause less pain and scarring than the larger incisions used in an open procedure. Depending on the location of the nodule, you may get knee arthroscopy, shoulder arthroscopy or arthroscopy on a different joint.
During an arthroscopic procedure, your healthcare provider:
The condition increases your risk of joint damage. In rare instances, a free-floating nodule may grow overly large. It may take up the entire joint space or invade nearby tissues. The joint may appear misshapen. You may lose the ability to fully use that joint.
Experts aren’t sure why some people develop synovial chondromatosis. There isn’t anything you can do to prevent the condition.
For close to 1 in 4 people who undergo surgical treatment, the nodules grow back. Your healthcare provider will order imaging tests and monitor the joint for signs of recurrence.
The condition also increases your risk for joint damage and arthritis. Your healthcare provider will continue to check you for signs of these issues.
Call your healthcare provider if you experience:
You may want to ask your healthcare provider:
A note from Cleveland Clinic
If you have arthritis or a different bone condition, you may be at risk for synovial chondromatosis. Sometimes, the condition develops for no known reason. When this happens, you have a higher risk of developing painful osteoarthritis. Regardless of the cause, most people who develop these tumors need surgery to remove them. You can talk to your healthcare provider about your treatment options. Even after surgery, your healthcare provider will monitor your joints for signs of tumor recurrence and joint damage.
Last reviewed by a Cleveland Clinic medical professional on 06/07/2022.
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