Dear Dr. Prescott,
What’s the difference between osteoarthritis and rheumatoid arthritis? Are they both caused by inflammatory reactions? And if that’s the case, why wouldn’t rheumatoid medications also be effective for osteoarthritis?
Ginger Coleman Kelso, Norman
While osteoarthritis and rheumatoid arthritis share inflammation as a common component, the conditions have different causes. That’s why some medications that target RA don’t work against osteoarthritis.
Osteoarthritis stems from wear and tear that erodes the cartilage between the bones in joints. The most common form of arthritis, it strikes more than 30 million Americans and typically affects fingers, hands, hips, lower back and knees. Pain often worsens with use and improves with rest, and we’re more likely to develop osteoarthritis as we grow older. Other risk factors include overuse, obesity and history of traumatic injuries (like an auto accident or a sports injury).
Doctors typically recommend that people with osteoarthritis engage in regular physical activity, which not only strengthens muscles that support the joints and helps control weight, but it also has been shown to reduce pain. They may treat it with nonsteroidal anti-inflammatory drugs like aspirin, ibuprofen (Advil), naproxen (Aleve) and celecoxib (Celebrex). In severe cases, physicians will inject corticosteroids into specific joints to help relieve symptoms. These tactics are aimed at mitigating the symptoms of osteoarthrits. Still, they don’t affect the underlying cause of the disease, which has no known cure.
Rheumatoid arthritis is less common than osteoarthritis, affecting a little more than a million Americans. Although researchers have yet to find its origins, they know the disease is caused by a dysfunction of the immune system. Specifically, the immune system perceives something inside the joints as foreign, prompting it to launch an attack. Tissues in the joint become inflamed and swollen, eventually leading to the destruction of cartilage and bone.
RA displays all the symptoms of osteoarthritis, plus noticeable joint swelling. But unlike osteoarthritis, RA symptoms are often worse in the mornings or after prolonged inactivity and improve a bit with use of the joints. Doctors use a combination of a physical exam, blood tests and X-rays to determine the type of arthritis a person has.
As with osteoarthrits, doctors use non-steroidal anti-inflammatories and corticosteroids to treat the joint pain and stiffness brought on by RA. But rheumatologists have a series of more specific disease-modifying therapies at their disposal for RA that can slow the progressive destruction of the joints.These potent medications use different approaches to alter the course of the underlying illness (although they still do not cure it).
The drugs target the immune system’s attack on the joint structures and generally fall into three categories. First, there are older compounds like methotrexate and hydroxycholorquine. Rheumatologists also use newer “biologics” such as Humira and Remicade, which are administered by self-injection or infusion in a doctor’s office. Finally, there is Xeljanz, the first of a novel category of oral inhibitors that block pathways involved in the body’s immune response.
While these drugs can help control RA, they will have no effect on osteoarthritis. That’s because the drugs target mechanisms in the immune system that are crucial to RA but have nothing to do with osteoarthritis.
As is so often the case in medicine, different diseases can have overlapping characteristics and symptoms. However, because their causes are distinct, what works for one condition won’t always work for the other.