What is a Hip Implant?

A hip implant is a prosthetic device used to replace the hip joint. The implant itself actually consists of two parts, the acetabulum and the femoral head, which replace their natural counterparts following amputation. The acetabulum is the concave surface of the pelvis that forms the socket of the joint, while the femoral head is the top of the thigh bone. Both parts are inserted during the same hip replacement operation.

Hip implant procedures, which have been performed for more than 100 years, are usually undertaken to relieve severe cases of arthritis, or following a fracture of the pelvis. While the first replacement femur heads utilized ivory, stainless steel has been in use since the 1940s. The acetabulum part is made out of a plastic material known as Ultra High Molecular Weight Polyethylene (UHMWPE). Both prosthetics are affixed to the surrounding bone tissue using a combination of acrylic bone cement and screws. More advanced designs avoid the use of cement entirely, and while more expensive, also last longer. Such units are generally offered to younger, more active patients because of their greater resiliency.

With advances in technology, hip replacement surgery can be performed earlier than in the past, and allows for the continuation of an active lifestyle with fewer compromises. It is considered the most successful type of orthopedic surgery, with a vast majority of recipients reporting an improvement following the operation. It remains, however, a last-resort option following pain management, physical therapy, and other treatments. Modern hip implant surgery can require as few as two incisions with the aid of computer guidance.

While the prognosis following hip implant surgery is generally good, there are complications that can arise, often relating to a condition known as osteolysis, which is the resorption of live bone tissue by the body. As the cement and implanted parts of a hip implant wear, small particles can flake off and cause this condition, which is progressive and often necessitates corrective surgery. Other issues can include stiffness and dull, chronic pain to severe trauma, like dislocation of the artificial joint.

A more conservative option to outright hip replacement is known as hip resurfacing. Instead of a complete amputation of the top of the femur, a metal cap is placed on top of the head of the bone. This allows for a more natural functioning of the joint than a full hip implant, and is a less traumatic procedure.