ABSTRACT
The hip is the most proximal joint in the lower extremity. It is a ball-and-socket joint. The femoral head (the ball) articulates with the acetabulum (the socket) in a very conforming fashion. The acetabulum is formed by the ilium, ischium and pubic bones of the pelvis. The presence of the femoral head is a necessary component to the formation of a normal acetabulum; for example, a patient with developmental dysplasia of the hip has a dysplastic acetabulum resulting from the absence of the femoral head in the socket during development. The acetabulum is deepened by the presence of a fibrocartilagenous labrum. The hip articulation is surrounded by the joint capsule and the iliofemoral and pubofemoral ligaments anteriorly and the ischiofemoral ligament posteriorly. The ligamentum teres runs from the acetabulum into the femoral head and carries a branch of the obturator artery, which is responsible for a significant part of the vascular supply to the femoral head during development. In adults, the major blood supply to the femoral head comes from the medial circumflex artery, a branch of the femoral artery. The greater and lesser trochanters of the femur serve as attachment sites for the major muscles and tendons about the hip. The abductors insert onto the greater trochanter and the iliopsoas, a major hip flexor, onto the lesser trochanter.
