There are more than 100 different forms of arthritis, a disease that can make it difficult to do everyday activities because of joint pain and stiffness.
Inflammatory arthritis occurs when the body’s immune system becomes overactive and attacks healthy tissues. It can affect several joints throughout the body at the same time, as well as many organs, such as the skin, eyes, and heart.
There are three types of inflammatory arthritis that most often cause symptoms in the hip joint:
Although there is no cure for inflammatory arthritis, there have been many advances in treatment, particularly in the development of new medications. Early diagnosis and treatment can help patients maintain mobility and function by preventing severe damage to the joint.
The hip is a ball-and-socket joint. The socket is formed by the acetabulum, which is part of the large pelvis bone. The ball is the femoral head, which is the upper end of the femur (thighbone).
A slippery tissue called articular cartilage covers the surface of the ball and socket. It creates a smooth, low-friction surface that helps the bones glide easily across each other. The surface of the joint is covered by a thin lining called the synovium. In a healthy hip, the synovium produces a small amount of fluid that lubricates the cartilage and aids in movement.
The most common form of arthritis in the hip is osteoarthritis — the “wear-and-tear” arthritis that damages cartilage over time, typically causing painful symptoms in people after they reach middle age. Unlike osteoarthritis, inflammatory arthritis affects people of all ages, often showing signs in early adulthood.
In rheumatoid arthritis, the synovium thickens, swells, and produces chemical substances that attack and destroy the articular cartilage covering the bone. Rheumatoid arthritis often involves the same joint on both sides of the body, so both hips may be affected.
Ankylosing spondylitis is a chronic inflammation of the spine that most often causes lower back pain and stiffness. It may affect other joints, as well, including the hip.
Systemic lupus erythematosus can cause inflammation in any part of the body, and most often affects the joints, skin, and nervous system. The disease occurs in young adult women in the majority of cases.
People with systemic lupus erythematosus have a higher incidence of osteonecrosis of the hip, a disease that causes bone cells to die, weakens bone structure, and leads to disabling arthritis.
Inflammatory arthritis may cause general symptoms throughout the body, such as fever, loss of appetite and fatigue. A hip affected by inflammatory arthritis will feel painful and stiff. There are other symptoms, as well:
During the physical examination, your doctor will evaluate the range of motion in your hip. Increased pain during some movements may be a sign of inflammatory arthritis. He or she will also look for a limp or other problems with your gait (the way you walk) due to stiffness of the hip.
X-rays are imaging tests that create detailed pictures of dense structures, like bone. X-rays of an arthritic hip will show whether there is any thinning or erosion in the bones, any loss of joint space, or any excess fluid in the joint.
Blood tests may reveal whether a rheumatoid factor—or any other antibody indicative of inflammatory arthritis—is present.