KEEPING THOSE JOINTS PUMPING
To relieve joint pain and loss of motion associated with osteoarthritis and rheumatoid arthritis, treatments run the gamut from powerful medications and physical therapy to joint implant surgery
by Lori Baker SchenaSeveral myths still exist about arthritis. Many people believe that there is only one kind of arthritis, that it only affects older people, and it is not treatable. "In reality," says rheumatologist Rodanthi C. Kitridou, M.D., USC professor of medicine, "there are more than 100 different types of arthritis that affect people of all ages. And effective treatments are available, although they differ with each type."
Arthritis is a common yet widely misunderstood disease despite the fact that it affects 37 million Americans-which translates into one in seven
people, or one in three families. The most common type of arthritis is osteoarthritis, which affects 16 million Americans. Also referred to as degenerative joint disease, osteoarthritis is caused by wear-and-tear of the large, weight-bearing joints and the finger joints. One percent of the U.S. population suffers from rheumatoid arthritis, which is an autoimmune disease that affects primarily the smaller joints of the hands and feet. Other kinds of arthritis include infectious arthritis, gout, psoriatic arthritis, systemic lupus erythematosus (Lupus), Lyme disease, Sjogren's syndrome and fibromyalgia.
Cartilage: When It's Gone, It's Gone ... Maybe
At the USC Center for Arthritis and Joint Implant Surgery, Director Lawrence D. Dorr, M.D., and Edward J. McPherson, M.D., treat patients with advanced degenerative osteoarthritis. At this point in their condition, the cartilage that covers the articular surface of the hip and/or knee bones has deteriorated, resulting in pain and loss of function. Through joint implant surgery, Dorr, professor of orthopaedic surgery, and McPherson, assistant professor of orthopaedic surgery, seek to ease this pain and restore function to the affected joints.
"There is a misconception that only older patients have osteoarthritis,"
says McPherson. "While many older people do require total joint replacements as a result of lifelong wear and tear on their cartilage, younger
individuals may also need this procedure by mid-life as a result of trauma-induced arthritis. We see this quite a bit in athletes who sustained knee injuries in their 20s and 30s. With an interarticular fracture of the knee, the joint surface has been damaged. Although the knee can be successfully repaired, the cartilage has been violated and is never the same."
McPherson adds that there is also a genetic component to post-traumatic arthritis. "Some individuals genetically have softer cartilage, making their joints more susceptible to wear and tear, both traumatic and long term. These individuals may have to retire from their sport earlier than their contemporaries, and will require joint implant surgery sooner than a person born with more durable cartilage." He cites tennis pro Jimmy Connors as an athlete who has "pristine knees." Despite a lifetime of wear and tear on the courts, his knees have withstood the test of time.
The ideal solution to cure osteoarthritis is to find a way for cartilage to regenerate itself. "We are nowhere close to this breakthrough because our understanding of how cartilage works is so primitive," Dorr says. "However, we are developing ways to transplant cartilage on the joint surface." In this sophisticated procedure, which was developed in Sweden, cartilage cells are harvested from the knee, hip or shoulder, cloned, and then used to patch a "pothole" defect on the cartilage surface of a joint that is showing signs of early damage from osteoarthritis. McPherson is one of the first surgeons on the West Coast to perform this technique. "If this procedure can be done successfully, we may be able to perform a limited cartilage transplant on someone in their 30s and 40s, and allow them to postpone a joint implant operation for 20 years or so," Dorr says.
Heavy Metal
In advanced osteoarthritis, the cartilage has degenerated to the point where bone scrapes against bone and there is no cartilage left to cushion the joint. Individuals with advanced disease are in great pain and lose the function of their joint. They are candidates for joint replacement surgery. Dorr has made several contributions to this field, creating total hip and knee designs that today are in wide use, and pioneering the development of a bone ingrowth system for total hips.
"There are two ways to fix a hip implant," Dorr says. "One is to fix it with bone cement, which creates an artificial link, and the other is to allow bone to grow into the implant, which in turn forms a biological link. With the bone ingrowth system, there is no need for cement." Today, 60 percent of hip replacement operations involve cement, a number that is likely to decrease as more and more orthopaedic surgeons learn uncemented techniques. "The cementless procedure is an easier operation, and has the potential to last longer than the cemented hip," Dorr says
Another recent advance in hip replacement is the use of modular surfaces-especially for patients who must have total hip replacement in their 40s or 50s. The Anatomic Porous Replacement System that Dorr developed for total hips is modular and consists of a metal shell that is implanted into the pelvic bone. A plastic insert is then placed into this metal shell. On the femoral stem, the femoral ball used to make the ball and socket articulation is also modular. The well-fixed stem and cup part of the replacement can last for several years, perhaps a lifetime. If the ball and plastic inserts that fit into the fixed cup do deteriorate, they can be exchanged, without the need to replace the entire system. "This exchange is much easier for the patient and surgeon because the stem and cup are already fixed to the bone," Dorr explains.
One of the biggest challenges in total hip replacement is the material used, specifically the metal head on the stem and the plastic insert lining the cup. The metal head tends to wear out the plastic, leading to failure of the hip replacement. One solution is developing a metal-on-metal surface, and USC has one of the most extensive clinical research experiences using metal-on-metal hip replacements. Although ceramic-on-ceramic is being researched in Europe, Dorr predicts that metal-on-metal surfaces will be available to community surgeons by 2000.
Rheumatoid Arthritis
Whereas osteoarthritis is generally caused by wear and tear, rheumatoid arthritis is an autoimmune disease. In rheumatoid arthritis, the white blood cells of the immune system move from the bloodstream into the joint tissues. Joint fluid may also increase. The white cells in the joint tissue and fluid produce many substances, including antibodies, that lead to the joint damage in rheumatoid arthritis.
Rheumatoid arthritis occurs in both childhood and adult forms. Bram Bernstein, M.D., professor of clinical pediatrics at USC and head of the Division of Rheumatology at Childrens Hospital Los Angeles, notes that there are about 100,000 children (age 16 and under) with juvenile rheumatoid arthritis (JRA). The disease is subcategorized based on one of three modes of onset.
The first mode of onset is called systemic JRA. Bernstein says the typical age of onset is between 3 and 6. Systemic JRA, which affects boys and girls in equal numbers, first occurs with frequent fevers. These occur usually late in the day or in the evening hours. Temperatures can go very high, during which time the child may become ill. Several hours later the temperature drops and then the child feels well again.
Many children with these fevers will develop a salmon-colored body rash that appears on the warmer areas of the body. This type of arthritis is called systemic because the internal organs may also be involved. Patients may experience inflammation of the lungs, enlargement of lymph nodes throughout the body, and an enlarged liver or spleen. Some of these children will develop a coagulopathy, which is spontaneous bleeding.
Bernstein says, "While these children may not initially exhibit true arthritis-swelling and loss of motion-eventually they will develop it. By definition, children have JRA if they have persistent arthritis-inflammation of joints-for six weeks." So far, researchers have not been able to locate any genetic markers for systemic JRA although it is hypothesized that the disease is due to a combination of an external antigen such as a virus and a congenital predisposition in the immune system.
The second form is polyarticular JRA, and this type most resembles adult rheumatoid arthritis. Thus it is not surprising that these children tend to be older (pre-puberty and puberty) and mostly females. The disease starts with many joints involved in a symmetrical pattern, affecting joints on both sides of the body. The disease tends to be chronic, and although it is variable in intensity, it is less likely than either of the other two forms to go into a complete remission.
The third form of the disease is the pauciarticular form, Bernstein says. Pauci is Latin, meaning a few; by definition, between one and four
joints are involved during the disease's onset period. These children, usually females between ages 2 and 5, are generally well, and the disease is localized. Not only is pauciarticular less likely to be functionally impairing since only a few joints are involved, but it has by the far the highest remission rate, with up to 70 percent of these children eventually going into a remission.
By ages 18-21, patients with JRA are referred to the USC Arthritis Program, where they continue to be followed. Kitridou notes that adult rheumatoid arthritis is a different condition from JRA, and its onset occurs after age 16. The majority of patients with adult rheumatoid arthritis have polyarthritis, which means five or more joints involved. Polyarthritis is symmetrical, affecting the joints of the hands, feet and wrist.
Kitridou says the symptoms of adult rheumatoid arthritis are mainly joint pain and swelling. Many times there is stiffness in the morning, which can last for hours in the severely ill patient. There may be slight, low-grade fever and some muscle pain and weakness. Other symptoms include "rheumatoid nodules," which can occur in the internal organs such as the lungs, as well as externally behind the elbows or on the wrists. Vasculitis, an inflammation of blood vessels, is a serious problem that can involve other internal systems.
From Aspirin to Methotrexate
Advances in both JRA and adult rheumatoid arthritis have occurred in the medications available to treat the disease and the philosophy in using these medications. "Traditionally," says Kitridou, "rheumatology treatment was prescribed in a pyramidal fashion, starting with general broad-based treatments and gradually shifting towards the more specific and potent treatment alternatives. But the tendency today is what we refer to as 'inverting the pyramid'- starting with specific, more potent medications to try to derail the disease process before it can do permanent damage."
When both Bernstein and Kitridou began practicing more than two decades ago, the only medications available were aspirin, prednisone (corticosteroids) and gold injections. "In treating JRA, we no longer use aspirin or gold, and prednisone is only used on a limited basis," Bernstein says. "Today we generally begin treatment with a rapid-acting, non-steroidal anti-inflammatory drug (NSAID), which is designed to stop the inflammatory process."
In JRA patients where NSAIDS alone are not enough, rheumatologists have a variety of choices including methotrexate, which for many years has been used in cancer chemotherapy. Methotrexate works in several ways, but most importantly it has anti-inflammatory properties. In small doses given once a week, it benefits both children and adults. Limited doses of cyclosporine, which suppresses the immune system, and cytoxan, a drug that destroys cells, are also prescribed in younger patients with advanced disease.
Physical and occupation therapy are also critical in caring for patients with both JRA and rheumatoid arthritis. Physical therapists teach patients joint and muscle exercises in order not to lose range of motion, and occupational therapists teach energy conservation, joint protection and self-care skills so the patient can live independently. Surgery may be indicated when there is intractable pain, tendon ruptures and loss of function.
In addition to clinical trials of new medications, bench research at USC is focused on the role of what is called a "super antigen" in causing autoimmune disease. "I believe we are gradually understanding the specifics of what is going wrong in rheumatoid arthritis," Bernstein says. "Once we know the exact cause of the disease, then perhaps we will be able to come up with a cure. That would, indeed, be a true breakthrough in the field of arthritis."