The hip is a ball-and-socket joint (enathrodial) consisting of the acetabulum and the femur. The acetabulum is the concave surface of the pelvis formed by the fused ilium, ischium and pubis bones and is the socket which the head of the femur fits into. This joint is lined by the acetabular labrum, a fibrocartilaginous tissue designed to deepen the socket and further prevent the femur from slipping out.

The most common type of arthritis of the hip is osteoarthritis. In this disease, the cartilage in the hip, especially the acetabular labrum, gradually wears away with use and time. Treatments for osteoarthritis include:

Rheumatoid arthritis is another type of arthritis that affects the hip. In rheumatoid arthritis, the hip becomes inflamed and cartilage may be destroyed. Treatment includes:

Avascular Necrosis (AVN) is a disease resulting from the temporary or permanent loss of blood flow to the bone. This can lead to the destruction of the bone and severe reduction in functionality of the joint. AVN is especially common in the hip and can be treated several ways:

Bursitis is the painful swelling of the bursae, fluid filled sacs on the cushion areas where tendons and muscles slide across bone. Specific to the hip is trochanteric bursitis (also known as greater trochanteric pain syndrome or GTPS), which refers to the bursa by the head of the femur. This shock absorbing sac can become agitated and swollen for unknown reasons or as a symptom of other issues such as gluteal tendon infections, uneven leg length or Iliotibial Band Syndrome. Steps can be taken to prevent bursitis by strengthening the core and hips through a moderate training program. Orthotic inserts for people with flat feet can also help. The condition can be treated by:

A hip pointer is a bruise on the iliac crest of the hip bone, usually caused by a strong physical blow, such as that in full contact sports. It can cause bleeding of the hip abductor muscles, making leg movement painful. A doctor can take X-Rays to see if there has been permanent damage to the iliac crest, but the issue generally resolves itself within four to six weeks.

Hip dysplasia is a misalignment of the hip joint that can either be congenital (present at birth) or acquired, but both are considered multi-factorial, meaning there must be more than just either of these two factors at work to cause the disorder. The congenital form has been linked to chromosome 13 and, much more rarely, chromosome 4.This condition can be acquired if an infant is swaddled too tightly and their hips get locked for long periods of time. Hip dysplasia can be detected early on through ultrasound as well as through X-Ray once the baby has been born. It is most often treated using a Pavlik harness to reassert correct alignment of the bones, although it is also possible the child will grow out of the misalignment. In severe cases, surgery to repair or replace the hip joint will be needed.