Synovial Chondromatosis

Synovial chondromatosis (also called synovial osteochondromatosis) is a rare, benign condition that involves the synovium, which is the thin layer of tissue that lines joints.

Although this type of tumor does not spread to other parts of the body, it can cause severe damage to the joint and lead to osteoarthritis. Early treatment is important to relieve painful symptoms and prevent further damage.

Anatomy

A joint is where the ends of bones meet, such as your knee joint, shoulder joint, or ankle joint. Healthy joints move easily because of a smooth, slippery tissue called articular cartilage. Cartilage covers the ends of your bones where they meet. Surrounding your joints are thicker bands of tissue called ligaments. They form a capsule that holds the joint together. This capsule is lined with a thin membrane called the synovium. It produces synovial fluid that lubricates the joint.

Description

In synovial chondromatosis, the synovium grows abnormally and produces nodules made of cartilage. These nodules may break off from the synovium and become loose inside the joint.

In this x-ray of an ankle, the calcified loose bodies are clearly visible (arrows).

The loose cartilage bodies in the joint may vary in size from a few millimeters (such as the size of a small pill) to a few centimeters (the size of a quarter). The synovial fluid nourishes the loose bodies and they may grow, calcify, or ossify (turn into bone). They can then roll around like loose marbles and damage the articular cartilage, causing osteoarthritis. In osteoarthritis, damaged cartilage becomes worn and frayed. Moving the bones along this exposed surface is painful.

In severe cases, the loose bodies may grow large enough to occupy the entire joint space or penetrate into adjacent tissues. Synovial chondromatosis most often occurs in the knee, followed by the hip, elbow, and shoulder. In most cases, only one joint in the body is affected.

Most cases of synovial chondromatosis occur in middle-aged people between the ages of 30 and 50. Men are affected twice as often as women.

Cause

Synovial chondromatosis occurs spontaneously. There are no known causes. This condition is not inherited.

Symptoms

The most common symptoms of synovial chondromatosis are similar to those of osteoarthritis: joint pain, joint swelling, and loss of motion in the joint involved. There also can be fluid in the joint, tenderness, grinding, and popping. The nodules can sometimes be felt in joints close to the skin (knee, ankle, elbow).

Doctor Examination

It is important to seek treatment as early as possible to relieve symptoms and prevent further arthritis.

Medical History and Physical Examination

After discussing your symptoms and medical history, your doctor will examine your painful joint. He or she will ask you to move it in various positions to see if there is pain or restricted motion. Your doctor will also look for creaking or grinding noises (crepitus) that indicate bone-on-bone friction.

Imaging Tests

Diagnostic imaging tests provide your doctor with pictures of your bones, muscles, nerves, cartilage, and organs. Imaging tests may help your doctor differentiate synovial chondromatosis from osteoarthritis.

X-rays.This test provides good images of dense structures, like bone. If the loose bodies are not calcified, however, they may not show up in an x-ray.

Other imaging tests. Loose bodies typically show up very well on magnetic resonance imaging (MRI), which creates better images of soft tissue. Computed tomography (CT) also provides your doctor with a more detailed picture than an x-ray, and loose bodies can usually be seen in these scans.

In addition to the loose bodies, imaging tests can show your doctor additional problems, such as fluid in the joint and signs of osteoarthritis (narrowing of the joint space and bone spurs).

(Left) In this x-ray of the knee joint, calcified loose bodies are barely visible (yellow arrows). (Right) This MRI shows a cross-section image of the same knee. The loose bodies show up clearly. Treatment

Treatment for synovial chondromatosis involves surgery to remove the loose bodies of cartilage. In some cases, the synovium is also removed. This can be done with an open surgical procedure or an arthroscopic one.

A traditional, open surgical procedure involves a single large incision. In arthroscopy, small incisions and miniature surgical tools are used to remove the loose bodies.

The end results of traditional and arthroscopic procedures are the same. Your doctor will discuss the surgical procedure that best meets your needs.

Recovery

How long it will take to return to daily activities will vary depending on the type of procedure you have. Your doctor will provide you with specific instructions to guide your rehabilitation.

Although not common, synovial chondromatosis can return. For a period of time after surgery, your doctor will schedule regular, follow-up visits to check for any recurrence. He or she will also monitor any progression of osteoarthritis. The amount of damage synovial chondromatosis has already done to the joint will influence the chance of arthritis developing.