Best Choice for Replacing a Damaged Femoral Head

Hip joint replacement is the way to go when the ball, or head, on the top end of the femur (thighbone) is damaged and can't be fixed. Arthritis affecting the hip joint is one cause of this type of damage. Another is avascular necrosis (AVN). AVN happens from a loss of blood supply to the top of the femur. The result is death (necrosis) of the femoral head. AVN commonly occurs from hip fractures where the broken ends of the bone actually shift--or displace. A displaced fracture near the top of the femur is routinely treated by replacing the head of the femur.

Doctors have two choices for replacing the head of the femur. They can replace the entire hip joint (ball and socket) by performing a total hip replacement (THR). Another option is to replace only the head of the femur, a procedure called hemiarthroplasty. The implant used for hemiarthroplasty comes in two styles. The round head of the femur that fits into the hip socket can be one piece. The other type, called a bipolar implant, has a stem with a ball on the end that swivels. The surgery to replace the head of the femur with a swivel implant is called bipolar hemiarthroplasty.

In this study, doctors compared the results of THR with bipolar hemiarthroplasty. They used patient reports and X-rays as the measures of success. Each patient had a THR on one side and a bipolar hemiarthroplasty on the other side. It turns out that most of the patients preferred the side with the THR. In addition to less pain on the side with the THR, patients reported better walking ability on that side.

Yearly follow up X-rays showed that the bipolar implant tended to cause the cartilage in the socket to break down. Another consideration is a higher rate of second operations needed after a bipolar hemiarthroplasty. However, the chances for hip dislocation after surgery are higher for THR compared to bipolar hemiarthroplasty.

The authors conclude that THR is a more involved operation. For cases when the head of the femur is damaged, THR showed better results than bipolar hemiarthroplasty. The authors' conclusion agrees with those of other similar studies.