The hip joint is a “ball and socket” joint located where the thigh bone (femur) meets the pelvic bone. The upper segment (“head”) of the femur is a round ball that fits inside the cavity in the pelvic bone that forms the socket, also known as the acetabulum. The ends of the bone are covered with a smooth, cushioning layer called articular cartilage. The articular cartilage is what allows the bones to glide smoothly. While the cartilage covers the entire head of the femur, the acetabulum cartilage is in the shape of a horseshoe with a depression (fossa) in the center of the socket. This fossa contains soft tissue and a ligament connecting the femoral head to the socket.
The socket has a rim of rubbery fibrocartilage called the labrum. The labrum acts as a gasket, sealing in joint fluid and maintaining lubrication and nutrition. In addition, numerous tendons surround the hip, as well as bursae, which are lubrication "cushions" where soft tissues glide over bony prominences.
There are many factors that can cause pain and lead someone to seek medical treatment for their hips, among them abnormal anatomy a person is born with, or conditions that develop during the growth and development of the bones grow in childhood or adolescence. Trauma, as well as the wear and tear that occurs with aging can all lead to progressive arthritic changes. Hip pain in athletes is commonly the result of a muscle strain or tendonitis. The diagnosis and management of hip injuries has evolved substantially with the advancement in diagnostic tools such as magnetic resonance imaging and with new minimally invasive techniques and in hip arthroscopy.