Synovial Chondromatosis

Synovial chondromatosis is a condition in which small, noncancerous tumors grow in the space around a joint (the joint capsule). The tumors are made of cartilage. (Chondromatosis means abnormal cartilage growth.) They grow out of the thin membrane that lines your joint capsule (the synovial membrane).

Normally, your synovial membrane lubricates your joint and helps reduce friction when it moves. But when there are tumors growing out of it, friction does occur. The tumors can also break off and become loose bodies inside the joint capsule. They can irritate and damage the tissues or get stuck in the joint.

Types of synovial chondromatosis

Synovial chondromatosis can be primary or secondary.

• Primary synovial chondromatosis occurs unexpectedly in otherwise normal joints, for unknown reasons. This type is relatively rare. It tends to occur earlier in life, usually in your 30s or 40s.
• Secondary synovial chondromatosis occurs in joints that are already damaged by degenerative or inflammatory disease. This is more common. It tends to occur later in life, in your 50s or 60s.

Sometimes, the cartilage tumors harden into bone (ossification). Healthcare providers call this synovial osteochondromatosis (osteo- means bone). Other names for this condition include synovial chondrometaplasia and synovial osteochondroma. (Osteochondroma is a noncancerous bone tumor.)

Symptoms of synovial chondromatosis

Synovial chondromatosis causes symptoms similar to arthritis. It’s usually in just one joint, but sometimes it’s in the same joint on both sides (like both your knees). Joint pain and swelling are the most common complaints. Most people have pain when they’re at rest that gets worse when they move the joint.

You may also have:

• Bumps (nodules) that you can feel under your skin
• A grinding, creaking or popping sensation or noise when you move your joint (crepitus)
• Stiffness or trouble moving your joint as much or as far as you used to
• Instability or difficulty putting weight on your joint

Synovial chondromatosis usually occurs in larger joints that take a lot of daily stress, like your:

• Knees
• Hips
• Shoulders
• Elbows

Symptoms of synovial chondromatosis can be debilitating — like arthritis. But unlike arthritis, this condition is curable. Surgery can remove the tumors and stop them from damaging your joint. If you have worsening pain in a joint — even one that’s troubled you for a while — check in with your provider.

Synovial chondromatosis causes

Most of the time, synovial chondromatosis occurs in joints that have already taken a lot of wear and tear or damage from a chronic disease. In this case (secondary chondromatosis), the cartilage growing in your synovial membrane almost resembles a type of scarring process, similar to bone spurs on bones.

Some conditions that can set the stage for secondary synovial chondromatosis include:

• Osteoarthritis
• Inflammatory arthritis
• Osteonecrosis
• Osteochondritis dissecans

Primary synovial chondromatosis occurs for unknown reasons. Whereas the secondary type may develop from osteoarthritis, primary synovial chondromatosis can be the cause of osteoarthritis. Loose cartilage and bone pieces in your joint can irritate and wear down the soft tissues in your joint.

Risk factors

Besides preexisting joint disease, your sex is the most important risk factor. Synovial chondromatosis affects males four times more than females.

Complications of synovial chondromatosis

Synovial chondromatosis can cause permanent damage to your joint. The effect is like an accelerated form of osteoarthritis. The constant friction and inflammation in your joint wear down the cartilage and harden the synovial membrane. If this continues, you might eventually need joint replacement surgery.

Very rarely, a benign cartilage tumor can turn into a cancerous one. This is called chondrosarcoma.

How doctors diagnose synovial chondromatosis

A healthcare provider will examine your affected joint, then order imaging tests. Cartilage tumors in the joint will usually show up on X-rays. Occasionally, it may take a CT scan or MRI to see the smaller ones. Imaging tests may also show inflammation in your joint and evidence of tissue damage.

What is the treatment for synovial chondromatosis?

Treatment for synovial chondromatosis depends on how much the condition affects your joint. If tumors don’t cause too much discomfort or damage, your provider might suggest watching to see if this happens.

You can treat your symptoms at home with:

• NSAIDs (nonsteroidal anti-inflammatory drugs)
• Cold therapy (ice packs or ice baths)

But if loose tumors are getting stuck in your joint and seriously limiting your range of motion or damaging the cartilage in your joint, your orthopedist may recommend surgically removing them. Surgeons can often do it by minimally invasive surgery methods, like arthroscopy. But you may need open surgery if you have tumors in your hip or the back of your knee.

Additional procedures might include:

• Synovectomy: If you have a lot of tumors or they keep coming back after removal, your surgeon might suggest removing the synovial membrane from your joint to stop tumors from forming.
• Joint replacement: If your joint is badly damaged (often by other conditions in addition to synovial chondromatosis), your surgeon might recommend replacing it with a prosthetic one.

What can I expect if I have synovial chondromatosis?

Synovial chondromatosis can be damaging, but it’s treatable. Your outlook depends on how soon you get treatment, how much damage your joint has and whether the tumors come back after treatment. Your healthcare provider can tell you more about what to expect based on your unique condition.