Is Anterior Hip Replacement Better?

Donald Reilly, M.D.

Q. I have a severely arthritic hip. It's pretty clear that I'm a candidate for hip replacement. When I looked on the Internet, there were a lot of Web sites promoting "anterior hip replacement." What is it, and is it any better than the traditional approach?

A. Traditionally, orthopedic surgeons have approached the hip joint from the side and back when doing total replacement surgery. The incision used in this posterolateral approach, as it is called, is about six to nine inches long and is made along the side of the hip and the upper thigh. Anterior means front, and the incision for the anterior approach is made in the upper part of the front of the thigh.

The anterior approach does have a few advantages. There are a lot of claims about anterior hip replacement being less invasive or "tissue sparing." I think that's overstating it; the anterior approach is not less invasive. But there is a natural opening beside the sartorius muscle in the front of the thigh, so the anterior approach means the surgeon can gain access to the hip joint by separating muscle tissue rather than cutting through it. The posterolateral approach involves cutting through some muscle tissue, but the muscles affected (called the short external hip rotators) aren't important for common day-to-day movements, like walking. Besides, depending on the case, the surgeon can repair the hip rotators.

I do posterolateral hip replacements, so I may be biased, but I think there is a serious drawback to the anterior approach. The hip is a ball-and-socket joint, and regardless of the approach into the joint, a total hip replacement involves replacing the ball, which is the head of the large bone in the thigh called the femur, and the socket, which is the cupped part of the pelvic bone called the acetabulum.

The posterolateral approach to the hip gives the surgeon good access to the femur and allows him or her to ream it out and fit the femoral component of the replacement snugly into the bone. The access to the femur isn't as good with the anterior approach, which makes it more difficult to ream out the femur. As a result, surgeons often choose to use a type of femoral component that's thinner and more curved than the component used in a posterolateral operation. In my opinion, that type of component may not fit as securely into the bone.

Posterolateral approach

Some of the surgeons performing anterior hip replacements are promoting them as reducing the chances that the replacement will dislocate after the surgery. But surgeons using the posterior approach use techniques to repair the ligaments and other structures that hold joints in place (known collectively as the capsule), so the dislocation rate is less than 1 percent. And the anterior approach doesn't eliminate the possibility of dislocation: anterior dislocation, when the femoral component pops out in a forward direction, can also occur.

Some surgeons are promising that patients can resume normal activities right away after anterior hip replacement without crutches or even a cane. I think that's a really bad idea. It doesn't matter if the approach is posterolateral or anterior. If you put full weight on a hip replacement too soon after the surgery, you're running the risk of pushing the femoral component down into the bone and cracking the femur. Activity and exercise after a hip replacement speeds recovery, but it's also important to be careful about keeping your full weight off the hip and using crutches for a while.

The anterior approach is not new. For some patients, it's fine. But it's not clearly better than the more common posterolateral approach.

Donald T. Reilly, M.D., New England Baptist Hospital, Boston, Mass.

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