Q: What is the difference between rheumatoid arthritis and osteoarthritis?

A: Arthritis is a broad term that refers to numerous diseases that cause destruction of the joints. Both rheumatoid arthritis (RA) and osteoarthritis fall under this category, but are very different.

RA is an abnormal immune system response that causes the body to attack the soft lining of your joints because it perceives them as a threat, similar to a virus or bacteria.

The main symptoms of RA are joint pain, stiffness and swelling. It primarily affects middle-aged and young men and women. It is a chronic disease that people live with for life. If a patient shows symptoms of RA, a rheumatologist might order diagnostic tests including, but not limited to, blood tests, X-rays, joint ultrasound, and magnetic resonance imaging (MRI).

The goal for treating RA is to preserve joint function to enable the patient to remain active and independent. The most common medication used to treat RA is methotrexate. It is part of a category of drugs called disease-modifying antirheumatic drugs (DMARDs) that stop and/or reduce the progression of the disease. DMARDs include relatively newer medications — some are injectable biologics (biologics are proteins that live and engineered cell cultures make); others are oral medications that have specific targets in the body to slow the progression of joint inflammation and damage.

Steroids are powerful and fast-acting anti-inflammatory medications. A rheumatologist might give steroids to a patient who has RA to reduce severe inflammation until DMARDs take effect. Doctors prefer to use them for very short periods and in low doses because of the long-term risks of negative side effects.

Osteoarthritis, the most common form of arthritis, is a progressive joint disorder that initially breaks down the cartilage that cushions joints and eventually the bone underneath. This causes bones to rub against each other and leads to significant pain and potential limitation in function. Osteoarthritis is more common the older a person gets, mainly because of years of wear and tear on the cartilage and bone of the joint.

Osteoarthritis has a wide range of conservative treatment options, ranging from pain control to physical therapy, weight loss, and joint injections. Treatment options depend on the location, size and severity of the affected joint. Exercising regularly and maintaining an ideal weight are keys to managing and preventing pain, especially in such weight-bearing joints as knees and hips.

Unlike RA, there is no disease modifying agent for osteoarthritis, so there hasn’t been a widely used medication developed to stop osteoarthritis from progressing.

In more severe cases — often when a patient has persistent, continuous pain and significantly impaired joint function — a doctor might recommend surgery to repair or replace a joint.

Anan Haija is the medical director of rheumatology at AtlantiCare Physician Group, in Galloway, N.J.