Medical Services Total Joint Center Total Hip Replacement Find a Location Find a Provider Total Joint Center Menu Department Phone Numbers Total Knee Frequently Asked Questions Pre-op Post-op Information for Caregivers Total Hip Frequently Asked Questions Pre-op Post-op Information for Caregivers Patient Success Stories Total Shoulder Frequently Asked Questions Pre-op Post-op Total Ankle Commonwealth Orthopaedic Centers Learn About Our Hip Replacement Procedure A healthy hip is a ball and socket joint. The ball is the top of your femur (thigh bone) and the socket is the bottom of your pelvis. Cartilage covers the head of the femur (top of the thigh bone) allowing the ball to move easily and smoothly within the socket. With the help of the muscles surrounding your hip, you are able to walk easily without pain. In an unhealthy hip, the cartilage usually becomes worn away in places. Without cartilage, there is no protection between the bony surfaces of the ball and socket, causing them to become rough and begin to grind into one another. This causes pain and results in stiffness and discomfort when walking. It is usually at this point that you and your surgeon will make the decision to perform a hip replacement. A hip prosthesis is made up of a ball and a cup (socket). The ball is usually metal or ceramic and replaces the head of the femur (top of the thigh bone). The cup (socket) which is usually plastic, replaces the socket of the pelvis. Following the replacement, there is no grinding between the two surfaces, which should allow you to walk with ease and without pain. It is important to realize that you will be responsible for a major portion of your rehabilitation. Rest assured that there will be many healthcare professionals there to guide you step-by-step.