Treatment Options for Failed Total Hip Replacements
Treatment of the failed or infected total hip is very individualized. The basic rule of thumb is to fix what is “broken.” Typically the implants used in revision surgery are different than the original implants. This is especially true on the femoral side where bone loss is typically most pronounced. The femoral revision implant tends to be longer and bigger in diameter. Some of these implants actually replace parts of the femur that are missing due to osteolysis or as a result of removing the failed implant. In cases of severe bone loss on the acetabular side, special implants may be necessary.
Many times, bone graft is used in revision surgery. Bone graft may be obtained from another area of the body or may be “off the shelf.” The “off the shelf” variety is processed cadaveric bone or a synthetic bone. The most common used is the cadaveric bone as it is easily available and safe. The synthetic bone can be used in situations not requiring immediate structural support.
Case 1 – Loosening
When possible, only the loose part of the joint is removed and replaced. Since the hip replacement is basically comprised of the acetabular and femoral components only the loose component will be revised. However, sometimes the implants are so old; the implant that is not loose can not be matched with the new component that will replace the loose one. In this case, both components are removed and replaced.
Case 2 – Wear without loosening
In the case of worn bearings, only the acetabular liner and femoral head will be replaced. Sometimes there can be substantial osteolysis in the face of implants that are not loose. This requires bone grafting in addition to replacement of the bearing surfaces.
Case 3 – Chronic dislocation
Sometimes a hip is unstable and cannot become stable without surgery. This problem can be solved by multiple different methods. Surgery may include moving one or both components into a better position. Stability can also be achieved by merely changing the head or liner. Occasionally, a constrained liner can be used. This special liner captures the head making dislocation very difficult.
Case 4 – Infection
For reasons discussed above, in the face of an infected total hip replacement, the implants are completely removed and cement mixed with antibiotics is placed in the joint space. The patient is then given intravenous antibiotics for a minimum of six weeks. A month after the cessation of antibiotics, an aspiration of the joint is performed to assure the joint is bacteria free. Once the infection is completely gone, new hip prostheses can be implanted.