Synovial Osteochondromatosis

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.


What is synovial chondromatosis?

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.


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What do the terms “synovial” and “chondromatosis” mean?

You may better understand this condition by defining the parts of each word:

  • Synovial refers to your synovium, a thin layer of tissue that lines your joints. Your synovium makes synovial fluid, a lubricant that helps joints move and glide. Your joints, bones and synovium tissue are all part of your musculoskeletal system.
  • Chondro (or chondral) refers to cartilage. This type of connective tissue cushions bones inside of your joints and keeps them from rubbing together.
  • Matosis (or mitosis) refers to cell changes that occur within tissue.

What are other names for synovial chondromatosis?

You may also hear these terms:

  • Reichel’s syndrome: German surgeon Friedrich Reichel first described this condition in 1900.
  • Reichel-Jones-Henderson syndrome: In the early 1900s, American orthopaedic surgeons Hugh Jones and Melvin Henderson advanced the medical study and understanding of the condition first identified by Dr. Reichel.
  • Synovial chondroma: The suffix “-oma” is the medical term for tumors, regardless of whether they’re cancerous (malignant) or not.
  • Synovial osteochondromatosis: “Osteo” means bone. For this condition, it refers to the ossification (hardening) of the tumor into a bone-like substance.


What parts of the body does synovial chondromatosis affect?

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.

How common is synovial chondromatosis?

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.


What are the types of synovial chondromatosis?

There are two types of synovial chondromatosis:

Symptoms and Causes

What causes 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.

What are the symptoms of synovial chondromatosis?

Synovial chondromatosis causes symptoms similar to osteoarthritis. Joint pain and inflammation are the most common complaints. The pain may worsen when you move your joint.

You may also have:

  • Bumps (nodules) that you can feel underneath your skin.
  • Decreased range of motion in your affected joint.
  • Fluid (edema) in your joint.
  • Grinding, creaking or popping sounds or sensations when you move your joint (crepitus).
  • Swollen, tender joints.

Where do symptoms of synovial chondromatosis occur?

Depending on the affected body part, you may have:

Diagnosis and Tests

How is synovial chondromatosis diagnosed?

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.

An X-ray usually detects loose nodules, but smaller ones might not show up. If an X-ray doesn’t find any nodules, you may receive a CT scan or an MRI to get a more detailed image of your joint.

These imaging tests aid the diagnosis. They also can show signs of osteoarthritis and fluid in your joint.

Management and Treatment

What are nonsurgical treatments for synovial chondromatosis?

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.

What are surgical treatments for synovial chondromatosis?

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:

  • Makes several small incisions in your skin.
  • Inserts a tiny camera device (arthroscope) into one opening.
  • Inserts surgical instruments into the other openings.
  • Views a video screen to perform the procedure and remove the growths.
  • Removes the camera and instruments.
  • Closes the incisions with dissolvable stitches or a bandage.

What are the complications of synovial chondromatosis?

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.


Can you prevent synovial chondromatosis?

Experts aren’t sure why some people develop synovial chondromatosis. There isn’t anything you can do to prevent the condition.

Outlook / Prognosis

What is the outlook for someone with synovial chondromatosis?

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.

Living With

When should I call the doctor?

Call your healthcare provider if you experience:

  • Decreased range of motion in a joint.
  • Severe joint pain and swelling.
  • Unusual popping or grinding sounds or sensations in joints.

What should I ask my provider?

You may want to ask your healthcare provider:

  • What caused the synovial chondromatosis?
  • What’s the best treatment?
  • Do I need surgery?
  • Do I have osteoarthritis? If not, how can I prevent it?
  • Should I look for signs of tumor recurrence or complications?

Additional Common Questions

Can synovial chondromatosis become cancerous?

It’s extremely rare for a benign bone tumor to become cancerous. However, there have been a few reported instances of the condition turning into chondrosarcoma, a type of bone cancer.

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.

Medically Reviewed

Last reviewed on 06/07/2022.

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