Periacetabular Osteotomy for Acetabular Dysplasia
Periacetabular osteotomy is a relatively recently introduced operation. It was first performed by Prof Reinhardt Ganz of Bern, Switzerland in 1984. This is now a well accepted procedure for acetabular dysplasia and reported results have been generally very positive.
The hip joint is a ball and socket joint consisting of the cup of the pelvis (acetabulum) and the top of the thigh bone (head of femur). Acetabular dysplasia is an underdevelopment of the hip socket where the acetabulum or cup is congenitally shallow. The periacetabular osteotomy is a surgical procedure to correct this deficiency of the hip socket.
Most patients with acetabular dysplasia do not have any symptoms until young adult life. It usually presents with exercise related hip pain, sometimes associated with a catching or clicking sensation. The condition is more common in women and can be familial. In some cases there has been a history of hip dislocation at birth. The pain at times can be quite severe. It is not uncommon for the patient not to have a proper diagnosis for some months or years. If the dysplasia is significant and is left untreated then there is a strong likelihood that osteoarthritis will eventually develop.
The procedure is technically demanding and there is quite a steep learning curve. The procedure should be carried out only by surgeons well trained or experienced in its technique. Mr Dunin has carried out approximately 70 such procedures and has visited Prof Ganz in Switzerland on several occasions. He has also presented his results to the Australian Orthopaedic Association and the Arthroplasty Society of Australia.
A detailed history and physical examination will be performed. Mr Dunin will explain to you on the x-ray the nature of the condition. X-ray changes of dysplasia usually include shallowness of the acetabulum with an upward sloping roof, and significant uncovering of the femoral head. Further tests may be required, such as a CT scan or MRI scan in some cases. However, in most cases sufficient information can be gained from plain x-rays.
Hip arthroscopy can occasionally be used in cases where there is a labral tear with very mild dysplasia, however, this procedure does not alter the natural course of the condition when the dysplasia is significant.
The operative procedure of periacetabular osteotomy will be explained including the potential risks and expected outcomes. This procedure has reliably relieved patients preoperative pain in a high percentage of cases. Many patients have a higher functional capacity, particularly for sports postoperatively and this effect can be quite long lasting.
Periacetabular osteotomy involves performing several bone cuts (osteotomies) around the acetabulum and redirecting it in an optimal position so that the femoral head is adequately covered. The osteotomy is then stabilised with about three screws. The xray demonstrates that the acetabular roof is now horizontal and there has been excellent covering of the femoral head. The procedure is a major operation with significant blood loss and many patients chose to donate their own blood prior to surgery. A Cell Saver is used during the operation to reinfuse the patients own blood during the operation. The procedure normally takes about 2.5 hours to perform. An image intensifier is used throughout the procedure. This is done to confirm correct positioning of the osteotomies, as well as to check for optimum positioning of the acetabulum.
The procedure will be performed under a spinal anaesthetic which numbs the pelvis and legs so you will not experience any pain or sensation of the procedure. Most likely you will also be given some sedation or a light general anaesthetic. With the spinal technique Morphine is sometimes injected as well as local anaesthetic. The advantages of Morphine is that it prolongs the postoperative pain relief. It can sometimes cause some postoperative itchiness, but this can usually be well controlled with other medication. A urinary catheter will also be inserted which will stay in position until you are mobile.
Postoperative Inpatient Stay
As the procedure is a major operation, some degree of postoperative pain is to be expected. In addition to the spinal anaesthetic, it can be well controlled by a variety of pain killing medication. Most patients get out of bed around day 2 to 4. It would be expected that you would still require oral pain killers on discharge, and this may be required for several weeks. It is important to remain minimal weight bearing for the first 6 weeks postoperatively. A physiotherapist will assist you in using crutches as well as protecting the weight bearing. Most patients are discharged at approximately 7 days post operation.
After Discharge From Hospital
Due to the extent of this major procedure you will feel quite tired in the first few weeks postoperatively and it is important to give yourself plenty of rest and not expect too much of yourself. The leg will feel quite heavy and in most cases you will need to use your hands to lift the leg in and out of chairs and cars.
You will be reassessed by Mr Dunin at the 6 week mark postoperatively, but should you have any concerns during these initial few weeks do not hesitate to contact him by phone.
It is not uncommon during these initial few weeks to notice a clicking sensation in the anterior groin and this is nothing to be concerned about. It usually passes with time. After the 6 week period you will be allowed to increase your weight bearing to partial weight bearing progressing to full weight bearing by 10 weeks postoperatively. At this stage some physiotherapy and rehabilitation exercises can be commenced. There is little point in doing them until there is sufficient healing of the osteotomy. Gentle stationary bike riding and hydrotherapy can be commenced at this stage.
It is expect that you will have a limp and some weakness in the leg for up to 6 months after the operative procedure. Patients continue to improve for up to 12 months postoperatively. It would not be expected to return to various sporting activities until at least 8 months postoperatively.
This is a major operative procedure and does carry with it some potential risks. These include wound infection and potential damage to surrounding nerves and blood vessels. It is very common for patients to experience some numbness in the outer thigh but this does not usually interfere with the function of the leg and in most cases resolves over some months. There is a very small risk of damage to the sciatic nerve, although great care is taken to protect the nerve during the procedure. IF this occurred it could cause altered feeling and weakness in the foot and ankle. In most cases this would improve spontaneously but there is a small risk that it could be permanent. Other risks include persistent pain in the hip, although the vast majority of patients obtain marked improvement in their preoperative pain levels.
This is very uncommon with this procedure due to the excellent blood supply. It may require antibiotic treatment or occasionally further surgery to wash the wound out.
Stretching of the nerve supplying the outer thigh is extremely common with this procedure. In many cases the area of numbness will diminish over several months, but in some patients it may be permanent. Stretching of the sciatic nerve is a very uncommon, but more serious complication. Damage to the sciatic nerve would cause numbness in the foot and an inability to lift the ankle upwards. When it does happen it is usually due to stretching of the nerve and recovery could be expected in the majority of cases, however there is a small risk that the weakness in the foot may be permanent. Damage to the main artery of the leg is very rare, but it is worth noting that there is usually a moderate degree of blood loss during the operation.
Ongoing pain in the hip
Most studies have shown that approximately 85% of patients obtain very good pain relief. There are some patients who do have ongoing pain which may be related to progression of the osteoarthritis.
Osteoarthritis of the hip
One of the aims of the operation is to prolong the function of the hip and to delay or prevent the need for a total hip replacement. In a small percentage of patients however, a total hip replacement may well be required years after the periacetabular osteotomy.
There is a small risk of delayed or non-union of the osteotomies. It is very important that you do not smoke for at least 6 weeks prior to surgery as this interferes with wound and bone healing.
Deep Venous Thrombosis
There is a small risk in blood clots (deep vein thrombosis) in the initial postoperative period. You will be given stockings to improve the blood flow through the leg and you will be encouraged by the physiotherapist to exercise the foot and calves frequently. In addition to the stockings, for the first 2 days foot pumps will be fitted to your foot and ankles. These mechanical devices actively contract your legs to also improve the blood flow. In addition, you will be placed on either Aspirin or subcutaneous injections of Heparin.
Further Postoperative Consultations
You will be reviewed by Mr Dunin over the next few months to assess your rehabilitation and healing of the osteotomy with periodic x-rays. Some patients experience some discomfort over the top of the screws which are located on the iliac crest. Once the osteotomy has united these can be simply removed as a day procedure.
Periacetabular osteotomy is a major procedure for a patient to undergo and it is important to give yourself plenty of time to reflect on the pros and cons of surgery before proceeding with this operation. It is sometimes not a bad idea to have two or more consultations with Mr Dunin regarding the management of acetabular dysplasia as there is often a lot of information to take in on one day. In addition, Mr Dunin can put you in touch with patients who have had the operative procedure to give you some insight as to what is expected of you in the postoperative period. If you have any particular queries it is a good idea to write them down and bring them along at the time of the consultations.
For further information regarding this procedure, click on this link: www.hipandpelvis.com.