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Hip Periacetabular Osteotomy (PAO)

Periacetabular osteotomy (PAO) is a procedure that has been around for sometime, but is not widely known about or practiced in the general orthopaedic community. The technique was more widely introduced by Prof Reinhardt Ganz from Bern, Switzerland in 1984 (Known as the Ganz or ‘Bern’ese Periacetabular Osteotomy). The PAO is a world wide accepted procedure for acetabular dysplasia and hip impingement from excessive retroversion. There have been excellent outcomes in correctly selected patients. The aim of the PAO is to cut around the bone acetabulum (socket), and reorient the socket to a functional position correcting the underlying shape problem. Generally 85% of patients have good to excellent outcomes.

Dr Agolley is a hip surgeon on the Gold Coast and performs Periacetabular Osteotomy (PAO) for Acetabular Dysplasia or Excessive Retroversion. The periacetabular osteotomy procedure is technically demanding. Only surgeons trained or experienced in its technique should only carry out the procedure. Dr David Agolley has completed a fellowship in minimally invasive PAO with Mr. Johan Witt (who learned the procedure by the now retired Prof Ganz) at UCLH London, UK.

The aim of periacetabular osteotomy (PAO) surgery, is to improve the pain coming from your hip, and to improve your function with return to an active lifestyle. It is also anticipated that the risk of developing osteoarthritis in the hip joint is reduced in the long term, depending on the pre-existing damage in the hip joint.

Conditions requiring PAO surgery

Acetabular Dysplasia

The main feature of hip dysplasia that contributes to pain in the hip is the acetabular dysplasia (shallow socket). The hip joint is a ball and socket joint, were the ball (head of the femur or thigh bone) and the socket of the pelvis (acetabulum) come together to form the hip joint. Acetabular dysplasia is an underdevelopment of the hip socket where the acetabulum develops too shallow over time. The shallow socket may be too shallow to contain the femoral head with adequate stability. Thus there is instability and subluxation of the hip leading to labral tearing, early arthritis of the hip joint, and hip pain. Typically patients have groin pain with activity.

Dr Agolley performs PAO to reorient the direction of the socket, to better cover the femoral head, and improve stability of the hip joint.

Learn more about Hip Dysplasia


Excessive Retroversion

The socket of the hip joint, is normally directed opening forward, allowing room for the hip joint to flex so you can sit in a regular or even a deep chair without the femur and rim of the socket abutting. In patients with excessive retroversion, the socket does not tilt forward enough, thereby causing the front rim of the socket and femur to abut causing symptoms of hip impingement. Hip arthroscopy may not be appropriate to alleviate the impingement, particularly if the socket is already shallow.

Learn more about Hip Impingement and labral tears

What investigations will be required?

Standing AP pelvis X-ray and supine AP pelvis with hips in Abduction and shoot through lateral of both hips are always essential. Dr Agolley will request further scans if indicated after consultation.

When should I have surgery?

Non-surgical treatments such as low impact activity (swimming and cycling), keeping your weight down, changing your activity or occupation, using a walking aid (stick) in your opposite hand to the hip pain, physiotherapy and taking pain medication can be helpful.

When non-surgical treatments are not working, Dr Agolley will discuss your options in proceeding with PAO. PAO is a hip preserving procedure, and for very worn hips PAO may not be the best option for successfully improving your hip pain. In these situations, total hip replacement is usually the single most reliable procedure to eliminate pain and restore high level of function. Dr Agolley will discuss your options with you at length.

The procedure and post-operative recovery

Minimally invasive surgery (MIS) Periacetabular Osteotomy (PAO)

Periacetabular osteotomy was initially performed by a very long and extensive incision. Over time a new approach that minimizes the incision, positioning it such that it is not visible with beachwear, has been developed. The other advantages of this approach are the immediate recovery, and medium to long-term rehabilitation is quicker. The periacetabular osteotomy involves performing several bone cuts (osteotomies) around the acetabulum and redirecting the acetabulum (hip socket) to an optimal position where the femoral head is adequately covered. The osteotomy is stabilised with screws that can be removed at a later date if required. Intraoperative imaging demonstrates correction of the shallow socket.

The post-operative recovery consists of:

  • Multimodal pain relief therapy with local anaesthetic, patient controlled analgesia, and a pain pump infuser
  • Most patients get out of bed on day 1 and go home between day 5-7
  • Partial weight bearing through the operated limb for minimum 6 weeks
  • Full weight bearing comfortably by 8-10 weeks
  • Supervised rehabilitation by physical therapy
  • Jogging by 4-6 months
  • Return to full sport by 8-12 months
  • Drive when you can walk comfortably off crutches

Specific precautions

There may be numbness on the side of the thigh. This usually resolves quickly, but may persist for a few weeks. Major nerve or blood vessel injury is uncommon. It is rare to require a blood transfusion after surgery. Blood clots in the legs and lungs are also very uncommon with compression stockings, exercise and blood thinning treatment. Infection is uncommon as several steps are taken to minimise risk. Delayed or non-union of the small cuts around the acetabulum is uncommon in non-smokers. Depending on the shape of the patients’ hip and the extent of the damage to the hip joint before PAO, osteoarthritis may still occur later in life requiring hip replacement to alleviate pain.

More Information

For more information, see the International Hip Dysplasia Institute.