Hip Anatomy

Hip Anatomy

To help you fully understand the process of total hip replacement, it may be useful to have an understanding of what a hip is and how it works.

 Hip image courtesy of



The hip is actually a ball and socket joint, uniting two separate bones – the femur (thigh bone) with the pelvis. The pelvis features two cup-shaped depressions called the acetabulum (socket), one on either side of the body. The thigh bone is the longest bone in the body and connects to the pelvis at the hip joint. The head of the thigh bone, shaped like a ball, fits tightly into the socket, forming the ball and socket joint of the hip, allowing the leg to move forward and backward and side to side, and rotate right and left.


The socket is lined with cartilage, which cushions the bones during weight-bearing activities and allows the joint to rotate smoothly and freely in all planes of movement with minimal friction.


The complex system of ligaments that connects the thigh bone to the pelvis is essential for stability, keeping the hip from moving outside of its normal planes of movement.


The muscles of the hip joint have dual responsibilities, working synergistically to provide the power for the hip to move in all directions, as well as to stabilize the entire lower extremity during weight-bearing activities.

A healthy hip will allow the leg to move freely within its range of motion, while supporting the upper body and absorbing the impact that accompanies activities like running and jumping.

Click here for information on arthritis of the hip

Click here for information on treatment options for arthritis of the hip