The hip joint is a ‘ball and socket’ joint. The hip joint allows movement to occur between the thigh bone (Femur), and the hip bone (Pelvis). The pelvis contains the ‘socket’ called the acetabulum. The ball-shaped head of the femur fits into the acetabulum, forming a ball and socket joint that enables the leg to have a wide range of movements. The outer surface of the femoral head and the inside surface of the acetabulum are covered with cartilage. The cartilage surface is a tough and very smooth material that allows the two surfaces to slide against one another with ease during movement. Envelopes of tough ligaments connect the pelvis and femur, covering the joint and stabilising it. The hip joints' movements are initiated and controlled by the thick muscles of the buttock at the back and the thick muscles of the thigh at the front. A healthy hip joint allows the leg to move freely within its range of motion, while supporting the upper body and absorbing the impact that results from activities such as walking and running.
An articular surface replacement aims at restoring this normal biomechanical relationship and so enable normal function of the hip after articular surface replacement and once the muscles are back to normal strength.
