The hip joint is a ball and socket synovial (fluid filled) joint. The hip joint allows the femur the motions of flexion, extension, abduction (moving away from the body), adduction (moving toward the body) and rotation.
A very stable joint, the hip joint is formed by the union of the head of the femur (ball) and the acetabulum (socket) of the hip bone (Fig.1). The hip bone is comprised of the ilium, ischium, sacrum, pubis and coccyx.
The femoral head is covered with a variety of hyaline cartilage called articular hyaline cartilage (Fig.2).