PAO Frequently Asked Questions

1. What does periacetabular osteotomy (PAO) mean?

The term periacetabular osteotomy means a surgical procedure involving the cutting of bone around the acetabulum (the hip socket)

2. Who developed this procedure?

The procedure was developed by Prof. Reinhold Ganz, an orthopaedic surgeon in Switzerland and Dr. Jeff Mast, an American orthopaedic surgeon.

3. Who would benefit from this operation?

The indications for the procedure include any patient with a mechanical abnormality of the hip secondary to malpositioning of the hip socket.

4.How does cutting the bone and moving things help my hip pain?

The theories of hip pain include instability of the hip due to lack of containment of the femoral head, excessively high pressures within the hip due to poor coverage of the femoral head, and abnormal contact or impingement of a portion of the femur with that of the hip socket (acetabulum).

5.Why not just have a total hip replacement instead of going through with this operation?

A total hip replacement is a major procedure with substantial restrictions of activity, numerous potential modes of failure, progressively declining success at each revision (repeat hip replacement). If a patient were to have hip dysplasia and undergo a total hip replacement in their thirties, there is a very high probability that they would need at least one to two further repeat hip replacements. Each time that this is performed, the patient would have a higher risk of losing bone, getting an infection, having a longer operation time, more blood loss, and other risks. The ultimate goal of orthopaedic surgery is to maintain the patient’s own joints until they can no longer function. A periacetabular osteotomy has been shown to increase function, decrease pain, while avoiding some of the long-term risks associated with joint replacement. As far as activities, a periacetabular osteotomy would give the patient a higher chance of resuming very vigorous activities that would be precluded for a total hip replacement.

6.How long is the recovery?

The procedure involves the cutting of the pelvis at specific points with complete mobilization of the hip socket. The socket is then fixed in place with screws. Post-surgical weightbearing is restricted for at least 6 weeks and sometimes longer until there is evidence of healing on the x-rays.

7.I am a young female… Will I be able to have children after this procedure?

One of the major advantages of this procedure over other types of pelvic osteotomy is the minimal effect on the birth canal. Most patients are allowed to have a normal vaginal delivery if they become pregnant at some point after undergoing PAO.

8.What is the success rate with this operation?

The success rate depends on a number of factors. First and foremost, the need for conversion to a total hip replacement at some time in the future is related to the degree of arthritis present in the joint at the time of the osteotomy. Other factors include the degree of deformity and the degree of correction achieved. Overall, if the hip has little to no arthritis, the success rate for avoiding a hip replacement is greater than 90% for at least ten years if not longer.

9.What are the complications of this operation?

There are a number of complications. Overall, however, the major complication rate is about one out of fifty cases. The most common minor complication rate is some numbness on the outer part of the hip from stretching of a nerve called the lateral femoral cutaneous nerve. This numbness rarely causes any problem for patients and the area of numbness usually gets smaller with time. Other complications include the risk of bleeding from the vessels within the pelvis, the risk of damage to nerves including the sciatic nerve which supplies many muscles in the leg, risk of the bones not healing properly or displacing, the risk of entry of the chisels used for the osteotomy into the hip joint itself, risk of infection (about 1%), the risk of anesthesia, risk of blood clots in the leg (deep vein thrombosis) or in the lung (pulmonary embolism), as well as other potential complications.

10.How long will I be in the hospital?

Most patients are in the hospital for 4-6 days.

11.How long will I need crutches?

Crutches are required for at least 8 weeks. Most patients are walking without any walking devices such as canes by the three month visit.

12.How often will I be seen in follow-up?

Patients are seen early on after their surgery to check the wound. They are then seen at 6 weeks, three months, 6 months, and then at one year.

13.What if the operation fails and I develop hip arthritis?

In the unlikely event that the operation were not successful and the hip goes on to arthritis, in many cases, patients report a high rate of satisfaction for several years after the operation. A total hip replacement can then be performed with minimal effect from the previous osteotomy. Another important factor is that every year new technology is available to make hip replacements last longer and preserve more bone for the future. Additionally, with time, medical research achieves greater and greater understanding about the response of the human body to joint replacements. Thus, delaying a hip replacement if at all provides these advantages to the patient.