Pigmented villonodular synovitis is a condition of the joint lining. It is characterized by pain and swelling as well as hemosiderin (iron) build-up inside the joint.
It occurs most commonly in the third and fourth decades of life.
Pigmented villonodular synovitis typically involves one joint. In 80% of patients, the knee is affected, but pigmented villonodular synovitis also can affect the hip, ankle, shoulder, and elbow.
Pigmented villonodular synovitis occurs in two forms: localized and diffuse, each of which involves a clinical spectrum of the same problem.
Localized pigmented villonodular synovitis
When the pain and swelling occurs in just one area of the joint, it is called localized pigmented villonodular synovitis. This type usually responds well to treatment.
Diffuse pigmented villonodular synovitis
When the condition involves the entire joint, it tends to be more destructive. Diffuse pigmented villonodular synovitis is more difficult to treat. Diffuse pigmented villonodular synovitis is significantly more common than localized pigmented villonodular synovitis.
The cause of pigmented villonodular synovitis is unknown. Genetic changes associated with pigmented villonodular synovitis have been identified, but the evidence for a genetic cause is not conclusive.
In addition to joint pain and swelling, patients with localized pigmented villonodular synovitis will experience joint locking, catching, and instability.
Patients with diffuse pigmented villonodular synovitis often present with a gradual onset of joint pain, swelling, and stiffness.
In both types, symptoms may occur sporadically.
Your doctor may recommend several diagnostic tests.
If it has not caused changes in your bone, pigmented villonodular synovitis may not appear on an x-ray. Your doctor may order x-rays to rule out other causes of pain.
Magnetic Resonance Imaging (MRI)
In localized pigmented villonodular synovitis, the MRI scan will show a nodular mass that may have bone changes.
In diffuse pigmented villonodular synovitis, the MRI scan will show extensive thickening of the joint lining or an extensive mass, possibly with destructive bone changes.
In this procedure, your doctor releases fluid from your joint. In many cases of pigmented villonodular synovitis, the joint fluid is bloody.
In most cases of pigmented villonodular synovitis, surgery is the best treatment option.
In the past, because of the high rate of surgical complications and local recurrence rates, physicians recommended observation (no treatment) until a total joint replacement was required. Today, with improved surgical techniques, the rate of surgical complications and local recurrence rates have decreased to such an extent that most patients are best treated with surgery.
For people who are not good candidates for surgery, anti-inflammatory medicines and muscle-strengthening exercises can help alleviate the pain and swelling.
There are several surgical techniques to treat pigmented villonodular synovitis. Your doctor will discuss with you the type of surgery that will be best for you.
Arthroscopic (camera placed inside the joint) partial removal of the affected joint lining with the mass is the treatment of choice for localized pigmented villonodular synovitis today. Arthroscopy is commonly successful because recurrence rates of localized pigmented villonodular synovitis at the same site are very low.
In patients with diffuse villonodular synovitis with both the front and back of the knee involved (most patients), open surgery rather than arthroscopy is often the best treatment. Your doctor will need to remove the mass and the entire joint lining to treat diffuse pigmented villonodular synovitis.
Combined Arthroscopy and Open Surgery
When most of the mass is in the back of the knee, a combined surgical approach can be undertaken. The back the knee is treated with open surgery to remove the mass and joint lining, and the front of the knee is treated with arthroscopic removal of the joint lining. This combined method decreases the magnitude of surgery, allowing for an easier recovery.
The recurrence rate at the same site is higher in patients with diffuse pigmented villonodular synovitis, but with proper surgical technique, the risk of recurrence can be minimized.
Total Joint Replacement
In its end stages, pigmented villonodular synovitis can cause extensive joint destruction. Once the joint has been significantly damaged, the best option to relieve pain and improve function is a total joint replacement.
Radiation therapy can sometimes be used for patients with diffuse pigmented villonodular synovitis that involves major nerve, tendon, or vascular structures or lesions that recur after surgery.
Radiation therapy is most commonly delivered via an external beam (treatment is directed from outside the skin to inside the joint). A newer method called intra-articular radiation (a radioactive fluid is injected into the joint with a needle) has been used as well.
Radiation therapy is usually reserved for patients in whom standard surgery has not been successful.
Postoperative physical therapy is extremely important in getting you back to your daily activities. Specific exercises will help you regain strength and range of motion.
Recovery from arthroscopic treatment for localized pigmented villonodular synovitis often requires a short course of physical therapy, after which you may return to normal activity.
Because the open surgical removal of diffuse pigmented villonodular synovitis is extensive, there is an increased risk of postoperative stiffness. A more regimented and extensive physical therapy program is required for patients recovering from open surgery to treat diffuse pigmented villonodular synovitis.
Recovery after open surgery involves an intensive, difficult, and prolonged physical therapy program. A return to normal daily activities could take months.
The American Academy of Orthopaedic Surgeons
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