The hip is one of the body's largest joints. It 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).
The bone surfaces of the ball and socket are covered with articular cartilage, a smooth, slippery substance that protects and cushions the bones and enables them to move easily.
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.
Description
Osteoarthritis is a degenerative type of arthritis that occurs most often in people 50 years of age and older, though it may occur in younger people, too.
In osteoarthritis, the cartilage in the hip joint gradually wears away over time. As the cartilage wears away, it becomes frayed and rough, and the protective joint space between the bones decreases. This can result in bone rubbing on bone. To make up for the lost cartilage, the damaged bones may start to grow outward and form bone spurs (osteophytes).
Osteoarthritis develops slowly and the pain it causes worsens over time.