Hip replacement is performed through a window in the soft tissues around the hip. Until the last few years, most hips were replaced from the side or posterior (back), but performing surgery from the front is gaining acceptance and good results.
In side or back replacement, muscles are detached to expose the hip joint and are then repaired at the end of the surgery.
Results have been reliable and the risks have been minimized over time, although problems do occur. The two most likely risks have been dislocation, in which the ball jumps out the socket, or leg length discrepancy, when the leg operated on becomes significantly shorter or longer than the other side.
The long-term results of hip replacement surgery are encouraging but far from perfect. Ninety percent of replaced hips are working about 10 years later; 80 percent are working 20 years later. Re-operation is unusual, but when it occurs, it is both expensive and dangerous.
Position of the socket within the pelvis is crucial to the overall survival of the hip replacement, and good position also seems to protect against dislocation. The current thought is that a well-positioned socket can survive 20 to 30 years or longer until the plastic material in the socket lining begins to break down. The better the position, it seems, the better the long-term survival of the hip replacement.
The anterior approach for hip replacements, in which the surgeon reaches the hip from an incision in the front, addresses all of these potential problems. The hip is accessed through a natural separation between muscles, so no muscle reattachment is needed. Thus, recovery comes more quickly. Live X-ray is used during surgery to ensure proper position of the socket and to check leg lengths so they are equal.
Over the last 18 months at Central Baptist Hospital, there have been no cases of hip dislocation after replacement using the anterior approach. The hip is solid, stable and ready for regular walking as soon as the patient feels strong enough. Regular walking can begin as early as one week after surgery.
The hip is so stable that precautions customarily taken with conventional hip replacement surgery have been discarded. There is no need to limit the motion of the hip to prevent dislocation. Legs can be crossed, and knees can be flexed and raised to the shoulder. Essentially, the advice is "Whatever you can do, do it."
Dr. Andrew W. Ryan, an orthopedic surgeon/partner with Lexington Orthopaedic Associates, practices at Central Baptist Hospital.