Normal anatomy of the Hip joint

The hip joint is a ball in socket joint composed of the acetabulum (socket) and the femoral head (ball). The joint is lubricated with synovial fluid, and has a shock absorber on both the acetabulum and the femoral head called joint or articular cartilage. The acetabular labrum is a suction cup attached to the rim of the socket, and this helps to hold the joint in place, and spread the lubrication around the joint.

Sometimes the labrum can be torn and cause pain, as it has a very dense innervation with pain nerve fibres. There are various ligaments which combine to form the capsule of the hip joint which holds in the joint fluid. When the articular cartilage wears out, this is called osteoarthritis, or arthritis for short. Generally the treatment for arthritis in the hip is some type of hip replacement surgery.