Painful and swollen joints characterize a number of orthopedic injuries and conditions, but in people with inflammatory arthritis, the immediate cause of the swelling and pain is usually inflammation and excessive growth of the synovium, a membrane that lines the joints.
"Normal synovium, which is usually one or two cell layers thick, produces synovial fluid that helps lubricate the joint," explains Mark P. Figgie, MD, Chief of the Surgical Arthritis Service at HSS. "When the synovium grows too bulky, it produces too much synovial fluid, which contains an enzyme that, in large quantities, ‘eats away’ at the articular cartilage on the joint surface."
In patients with inflammatory arthritis, excessive growth of synovium is part of an abnormal immune response in which the body recognizes cartilage as a foreign substance that must be attacked. Loss of cartilage eventually leads to damage to the joint surface as well as the stiffness and pain characteristic of all types of arthritis. (Osteoarthritis, the more prevalent form of the disease, does not involve this type of inflammatory response. Other causes, including injury, wear-and-tear, and heredity are thought to contribute to the degeneration of cartilage in osteoarthritis.)
Rheumatologists - physicians who specialize in the treatment of inflammatory arthritis, which includes rheumatoid arthritis, psoriatic arthritis, and juvenile rheumatoid arthritis - usually rely on a variety of medications to control abnormal growth of the synovium. These include both oral drugs known as DMARDs (disease-modifying anti-rheumatic drugs), and in some cases, steroid injections. Patients who don’t respond to these treatments may be referred to an orthopedic surgeon to discuss synovectomy, a procedure in which much of the synovium is removed.
(While the majority of patients who undergo synovectomy have one of these types of arthritis, synovectomy is also used to treat patients with synovial chondromatosus, a condition in which small calcifications develop in the synovium; individuals with pigmented villanodular synovitis, a rare condition in which very aggressive growth of the synovium occurs; and those with hemophilia. For more on the latter, please see the section below on radiation synovectomy.)
"Typically, we see patients who have had some improvement after six months of drug therapy but still have one inflamed joint that has not responded," says Dr. Figgie. In such cases, surgical reduction of the synovium can allow the medication to effectively control the condition. Other candidates for synovectomy are those for whom medication has provided no relief.
Synovectomy may be performed either as an open surgical procedure or with the aid of arthroscopy, in which the orthopedic surgeon uses miniaturized instruments, fiberoptic technology, and a tiny camera inserted through very small incisions in the skin. Magnified pictures from the camera are projected onto a television monitor in the operating suite, guiding the surgeon throughout the procedure.
Synovectomies may be performed on knees, elbows, wrists, finger joints, and hips. At HSS, many synovectomies are performed arthroscopically, but the choice of technique is often dictated by the affected joint. Using arthroscopy avoids the need for large incisions - an advantage if repeat synovectomies are needed - and allows for a faster rehabilitation. "It probably offers a more thorough removal of synovial tissue, as well," says Dr. Figgie. "But it is considerably more time-consuming than open surgery, and in some joints, more technically difficult to perform."
Synovectomy can yield dramatic improvement in function and pain relief, with patients whose articular cartilage is largely intact having the best results. Following surgery, the patient must continue to take medication to delay recurrence in the treated joint and to protect other joints. In some cases the medication dose may be reduced after successful synovectomy. "The goal is to slow the whole process of synovial overgrowth down and make the medication more effective," says Dr. Figgie. "Left untreated, the patient will develop more and more synovitis, which can eventually lead to complete destruction of articular cartilage and the need for joint replacement surgery."
Surgical synovectomy is associated with a low complication rate. Post-operative stiffness is treated with physical therapy. Range of motion exercises are essential, and patients are started on continuous passive motion (CPM) machines as soon as possible. Stiffness is more likely to occur after open surgery than with arthroscopy.
Patients with pediatric hemophilia sometimes develop synovitis as a result of recurrent bleeding into a joint. Shoulders, elbows, knees, and ankles may be affected. For this patient population, in whom surgery poses multiple risks, an alternative form of treatment may be used. Radiation synovectomy (also called isotopic synovectomy) involves the injection of the radioactive isotope P32 into the joint. "This substance stops the excessive growth of synovium, decreases the amount of bleeding, and appears to decrease the potential for arthritis," says Daniel W. Green, MD, an Assistant Attending Orthopedic Surgeon at HSS.
Radiation synovectomy is administered at HSS through a joint program with physicians at New York-Presbyterian Hospital. Donna Di Michele, MD, Director of the Regional Comprehensive Hemophilia Diagnostic and Treatment Center, works with Dr. Green and Robert Schneider, MD, Chief of the HSS Division of Nuclear Medicine, in treating young patients. Although radiation synovectomy has been used at other centers in the United States for more than 30 years, this program is the first in the New York City area.
Radiation synovectomy does not require hospitalization. After undergoing a pre-operative evaluation, the patient has an arthrogram, an x-ray of the joint that helps guide the placement of the needle. A topical anesthetic is administered, and the isotope is injected. The procedure takes about five minutes.
Radiation synovectomy: injection of radioactive isotope P32 into the knee joint
"This radioactive isotope is believed to be very safe," says Dr. Green. "We’ve now treated about 40 children with good results. In addition to the benefits described, radiation synovectomy avoids the problem of post-operative stiffness associated with surgery." Moreover, for some patients with hemophilia who have antibodies to their clotting factor and therefore can not tolerate surgery, radiation synovectomy is the only treatment option. Unlike patients with inflammatory arthritis, patients with hemophilia generally do not take any medication to control further growth of the synovium.
Summary prepared by Nancy Novick.