The operation of periacetabular osteotomy is designed to move the socket (acetabulum) of the hip joint so that it covers more of the femoral head (ball). The aim is to improve the biomechanics of the hip joint and reduce the high stresses that start to cause damage and arthritis because of the shallow acetabulum.
The operation is usually done with an epidural in place and under a general anaesthetic. The incision is curved over the outside of the pelvic bone and is typically 12-15cm long. The operation involves a series of bone cuts around the acetabulum, freeing it from the pelvis and allowing it to be moved to a new position. The new position of the joint is checked with X-rays at the time of surgery and once the optimal position for the hip has been achieved it is fixed in place with a number of screws.
After surgery, the epidural may be left in place for 24 hours for pain control and then with the aid of the physiotherapists you are taught to mobilise without putting significant weight through the leg using crutches. This amount of weight bearing is continued for 6 weeks and then provided everything looks alright on the x-ray or CT scan, weight is increased gradually so that full weight bearing is allowed 8 weeks after surgery. It will be necessary to use one crutch for somewhat longer that this while the muscles around the hip strengthen up and you will be given some specific exercises to practise. Patients usually find they can return to most activities after 3-4 months and to impact exercise and sports after 6 months.
The aim of the surgery is to improve the pain coming from the hip. It is also anticipated that the risk of the development or progression of arthritis will be reduced in the longterm, however, this depends a lot on how much arthritis damage has already occurred to the joint before surgery.
Risks and complications
Nerve and blood vessel injury. Because the acetabulum is surrounded by a lot of important nerves and blood vessels there is a small risk of damage to one of these serious structures. This could lead to some weakness in the lower leg. The overall risk of a major complication such as this is in the region of 2%.
Deep vein thrombosis and pulmonary embolus. During the recovery you will be treated with blood thinning injections and thromboembolic deterrant stockings to reduce this risk (2%).
Wound infections. These may occur about 1% of the time and may require antibiotics or further surgery to deal with them.
Failure of the osteotomy to unite. Because the pelvic bone has such a good blood supply and muscle cover, it would be very unusual for the osteotomy not to unite. If this were to happen then further surgery may be needed to stimulate the bone to heal.
Numbness around the wound and thigh. Because of the location of the incision for this operation and because of the anatomy of specific small sensory nerves, there is always some numbness over the upper outer aspect of the thigh. This area gradually gets smaller with time. Rarely the numbness may affect the outer aspect of a major portion of the thigh extending down to the knee but it would be unusual for it to persist to this extent.
Arthritis. In time the joint may become arthritic and this depends on the extent of damage before surgery and how shallow the acetabulum is. Although the aim is to make the hip look as normal as possible, it still won’t be a normal hip and therefore the stresses through it may result in the development of arthritis at some stage.
content written by Johan Witt Hip othopaedic and trauma surgeon
