Periacetabular osteotomy (PAO)

Periacetabular osteotomy (PAO) is a surgical treatment for hip dysplasia which preserves and improves the function of the patient’s own hip joint rather than replacing it with an artificial one. 

The goal of the PAO is to reduce or eliminate pain, restore function, and maximize the functional life of the dysplastic hip. PAO is designed to correct the major primary mechanical problems in acetabular dysplasia. These problems include excessive pressure of the femoral head on the rim of the acetabulum and instability of the femoral head within the acetabulum.

The ideal PAO patient has no or minimal damage to the interior of the joint, and sufficient, undamaged cartilage remaining within the acetabulum. In general, such patients have little or no narrowing of the cartilage space on regular x-rays and can flex their hips to at least 90° with minimal pain. 

The surgeon performing a PAO cuts the bone around the acetabulum in order to rotate it into a more stable, horizontal position of coverage on top of the femoral head. The pressure from the femoral head is now on the central portion of the acetabulum, where the cartilage is designed to accept this pressure. Additional hip procedures are sometimes indicated at the same time as the periacetabular osteotomy.  These may include arthrotomy (work inside the joint to repair rim damage) and proximal femoral osteotomy (cutting and realigning the head and upper end of the femur). Between four and twelve months after PAO surgery, most patients undergo screw removal as a brief outpatient procedure.

Example 1

This 14 year old boy has had multiple operations for hip dysplasia in the past. He was referred to Dr Balakumar for further evaluation and treatment.

Post operatively the patient experienced instant relief of symptoms and state that he “wished he had the operation earlier.” Dr.Balakumar states that in the “carefully selected patient joint preservation is the preferred choice”

After the PAO has healed and motion and strength have returned to a steady state, we encourage the highest level of “reasonable” activity that the hip joint will allow.  A corrected dysplastic  acetabulum is still at risk for damage by overuse.  Pounding types of activities, such as jogging are not encouraged. Though many of our patients are able to jog and even run marathons without a problem, the long-term impact on their joints is not yet known.

In general, since dislocation is not a risk after periacetabular osteotomy, there are no positional restrictions as there can be after total hip replacement.

We consider failure of periacetabular osteotomy to mean lack of improvement in pain, or an increase in hip joint stiffness serious enough to be limiting.  In such situations, a joint-replacing procedure of some type often becomes necessary.

Of our more than 800 patients who have had various types of periacetabular  osteotomies over the last 16 years, only about 40 have required a Total Hip Replacement (THR). The patients who have required THR have been the ones who had the  most damaged cartilage before the PAO surgery. Ten years or more post-PAO, more than 90% of  patients have little or no pain and well-functioning hips.

In patients who, along with their physician, select periacetabular osteotomy as the treatment of choice, we expect that their pain and function will be greatly improved by the surgery for a minimum of ten years and, hopefully, for a lifetime.  In all cases, the decision making process is one of open and honest communication between the surgeon and the patient.

Example 2

Another example is a 17 year old patient that saw Dr.Balakumar for previously treated hip dysplasia. She had a rebound hip dsyplasia with the ball trying to work its way out of the socket again.

Post Operatively you can see that the patient has excellent coverage of her right hip. Again the patient felt significant improvement of her symtoms. Dr. Balakumar utilized the cartilage mapping sequence to help him and the patient prognosticate the success of joint preservation procedures.