There are two main types of hip replacement operation, but a number of different components and surgical techniques may be used.
Total hip replacement
In a total hip replacement, part of the thigh bone (femur) including the ball (head of femur) is removed and a new, smaller artificial ball is fixed into the rest of the thigh bone. The surface of the existing socket in the pelvis (the acetabulum) is roughened to accept a new socket component that will join up (articulate) with the new ball component.
Many artificial joint components are fixed into the bone with acrylic cement. However, it’s becoming more common, especially in younger, more active patients, for one part (usually the socket) or both parts to be inserted without cement. If cement isn’t used, the surfaces of the implants are roughened or specially treated to encourage bone to grow onto them. Bone is a living substance and, as long as it’s strong and healthy, it’ll continue to renew itself over time and provide a long-lasting bond. Where only one part is fixed with cement, it’s known as a hybrid hip replacement.
The replacement parts can be plastic (polyethylene), metal or ceramic and are used in different combinations:
- Metal-on-plastic (a metal ball with a plastic socket) is the most widely used combination.
- Ceramic-on-plastic (a ceramic ball with a plastic socket) or ceramic-on-ceramic (where both parts are ceramic) are often used in younger, more active patients.
- Ceramic-on-ceramic (aceramic ball with a ceramic socket) is very occasionally used in younger, more active patients.