What is an osteotomy?
An osteotomy is the surgical cutting of a bone. In the treatment of developmental dysplasia of the hip (DDH), an osteotomy is usually performed on the pelvis or the femur, and in some cases, on both together. It is typically performed on children older than 18 months of age who have a shallow acetabulum (hip socket) or a misshapen proximal femur (upper thigh bone and ball). It is often performed together with an open reduction to help keep the hip in joint. Essentially, an osteotomy will reshape and realign the bones of the hip. As with all surgeries for DDH, all osteotomies are performed under general anaesthesia.
Pelvic osteotomy
The most common type of pelvic osteotomy that is performed at SickKids is the innominate osteotomy, also known as the Salter osteotomy after the orthopaedic surgeon from SickKids who developed it.
In a Salter osteotomy, the pelvis is cut, and the angle of the hip socket is rotated and redirected in order to align it better with the head of the femur. This method is the most common as it is ideal for most types of hip dysplasia. In some cases, another type of pelvic osteotomy may be used, such as the Dega or Pemberton osteotomies. Despite the differences in technique, all pelvic osteotomy methods aim to achieve the same thing: a better aligned hip joint. Your child's orthopaedic surgeon will determine the most appropriate procedure for your child’s particular problem.
A pelvic osteotomy requires the hip area to be opened up so that the pelvis bone can be accessed and reshaped. After making a cut in the pelvic bone and shifting the hip socket into the preferred position, special metal pins are used to hold the bones in position while they heal into their new shape.
Fluoroscopic imaging (live X-rays) is used during the procedure to ensure that the bones of the hip and the hardware (pins) are in the correct position.
After the operation is finished the child is sometimes placed in a single-leg hip spica cast to help stabilize the hip while it heals.
Femoral osteotomy
A proximal femoral osteotomy is performed when the upper part of the femur or the head of the femur needs to be redirected so that it fits into the hip socket better. This will allow for a better shaped hip joint as it grows. The proximal femur may need to be angled in, rotated, or sometimes even shortened to make sure the hip joint is properly realigned. A proximal femoral osteotomy is usually performed on children who are older than 18 months of age. Your child's orthopaedic surgeon will discuss the specific details of your child’s surgery with you.
Access to the top of the femur is achieved by making an incision (cut) in the outside of the upper thigh. The upper part of the femur bone is cut in such a way that it can be shifted, thereby changing the angle of the femoral head (ball). Metal screws and plates are used to hold the realigned femoral head in position while the bones heal into their new shape.
Fluoroscopic imaging (live X-ray) is used during the procedure to ensure that the bones of the hip and the hardware (plates and screws) are in the correct position.
After the operation is finished the child is sometimes placed in a single-leg hip spica cast to help stabilize the hip while it heals.
Combined pelvic and femoral osteotomy
In a combined osteotomy, both the pelvis and femur are realigned together during the same surgery. The bones in the pelvis are held together with metal pins, while metal plates and screws are used for the femur. As with the independent pelvic and femoral osteotomies, fluoroscopic imaging is performed during the operation to monitor the shape and position of the hip bones and the hardware.
This combined procedure requires that the child be placed in a single-leg hip spica cast for 6 weeks post-operatively.
Follow-up care after an osteotomy
After either a pelvic or femoral osteotomy your child will be seen in the outpatient clinic at 6-8 weeks post-operatively. At this visit, if a hip spica cast has been used, it will be removed by the orthopaedic technologists and an X-ray will be taken to ensure the hip has healed properly and it is properly aligned. Afterwards, your child will be allowed to weight bear (walk) at their own pace. Some children start walking within a few days, but others take a week or two, and this is quite normal. Physiotherapy is not usually required after osteotomy surgery. Your orthopaedic team will give you a lot of advice on how to manage the first few weeks after the spica cast is removed.
Further follow up appointments will be scheduled at 6 weeks, 12 weeks, 6 months and 1-year following surgery. At these appointments, X-rays of the hips will be taken, and the doctor will examine the hip’s health and growth. Most children who had surgery for hip dysplasia will need ongoing follow-up until they are fully grown to check that the hip continues to develop properly. The exact schedule of follow-up appointments will be determined by the orthopaedic team based on your child’s needs.
Hardware
The hardware, such as metal screws and pins, may be removed during a separate daycare surgery, under general anaesthesia, from 6 months to two years later. It is not always necessary to remove all hardware, and the surgeon will discuss with you the risks and benefits, and whether it is necessary in your child’s case to remove the screws and pins.
Complications of surgery
Despite extreme care taken during the operation, there is still the possibility that complications could occur. During follow-up appointments, your child’s health-care team will look for signs of complications. You should also monitor your child at home for signs of complications and contact the health-care team if you suspect any of the following.
Nerve injury
An injury to a major nerve near to the hip is a rare but serious complication of surgery. In general, nerve injuries can sometimes heal on their own but may also cause permanent disability of the hip and leg.
Vascular injury
An injury to a major blood vessel (artery or vein) near to the hip is a rare but serious complication of surgery. This type of complication may cause permanent disability of the hip and leg.
Infection
There is a risk of infection with any surgical procedure, including this type of hip surgery. The risk of infection is very low, occurring in less than 1% of cases. To help prevent infection your child will be given a single dose of a suitable antibiotic during surgery. Routine antibiotics are not prescribed after surgery as research has shown that a routine course of antibiotics does not reduce the risk of infection and may actually cause more harm.
Spica cast complications
It is very important to take good care of your child when they are in the spica cast otherwise serious complications can occur. A full description of how to care for the spica cast can be found in the article Caring for your child's hip spica cast. A spica cast that is too tight may cause pain and need to be released by the orthopaedic team. A tight cast would typically be identified in the first few hours after surgery. The skin under a cast can become very irritated by soiling of the cast, with urine or stool. Therefore, great care should be taken to keep your child clean throughout their time in the cast.
Delayed bone healing
Most operations on the bones of children heal within 6 to 12 weeks. It is very rare in children to have problems with bone healing after surgery, but it is possible. If there is a problem with delayed bone healing, then further surgery can be required to encourage the bone to heal.
Growth disturbance (Avascular necrosis)
In very rare cases, interruption to the blood supply of the hip joint (avascular necrosis) can occur which causes disturbance in the growth of the hip, specifically the femoral head (ball). It can take several years after the surgery to know whether growth disturbance has occurred. Fortunately, while these complications are not common, there are additional treatments available if growth of the hip is not as good as anticipated.