What is an open reduction?
An open reduction is a surgery where the hip joint is opened up so that the surgeon can remove any tissue that may be stopping the ball of the thigh bone (the femoral head) from going back into the hip socket (the acetabulum). Once the hip joint is cleared out, it is then reconstructed to hold the femoral head in place. Typically, an open reduction is performed on children with more severe hip dislocation that cannot be treated any other way. An open reduction surgery may be used for children between ages 9 and 18 months for whom a closed reduction was either unsuccessful or was not the best option, or it may be used as a first-line treatment for an older walking-age child. If your child is older than 18 months, an osteotomy (bone reshaping) is usually performed along with the open reduction. More information about osteotomies can be found in the article Osteotomy for developmental dysplasia of the hip.
How is an open reduction done?
There are five main steps to an open reduction. Each of these steps occurs after your child has been put under general anaesthesia.
Step 1. Adductor tenotomy
A very small incision (cut) is made in the groin and the surgeon releases the adductor tendon. By cutting this tight tendon, pressure on the soft surfaces of the hip is reduced, allowing the ball to stay in the socket better after the hip has been reduced. Cutting the tendon is nothing to worry about – it heals very quickly, much like a groin pull in an athlete.
Step 2. Muscle releases and clearing the socket
The surgeon will make one incision on the front of the hip (bikini line incision). This will allow the doctor to access the hip joint by releasing several tight muscles in front of the hip. The hip joint can then be opened so that any tissue blocking the ball from going back into the socket can be removed.
Step 3. Repairing the hip joint
Once the hip joint has been cleared, the ball can be manipulated back into the hip socket. The ligaments and muscles surrounding the hip will then be repaired and tightened to ensure that the hip stays in the joint. All of the soft tissues, including the skin, are repaired with dissolving stitches.
Step 4. Single-leg spica cast
The next step is to apply a hip spica cast to your child’s body. The cast goes from the upper chest down to the hips and then down just one leg to the ankle. The goal of the cast is to hold the hip joint in place so it can heal. The constant contact between the femoral head and the socket is what triggers the growth of the acetabulum into the preferred shape.
Step 5. Imaging
After the spica cast has been applied, and while your child is still asleep, the doctor will take images of the hip using 3D fluoroscopy. This is similar to an X-ray that shows the new hip position in great detail and ensures that the femoral head is held in the correct position, to allow for proper hip formation as your child grows.
Going home after surgery
Your child will be admitted to the ward after surgery for close observation. This also allows the nurses plenty of time to teach you how to take care of your child in the spica cast. An open reduction usually requires one night’s stay, so your child can go home the day after surgery if all is well.
Follow-up appointments after surgery
Your child will be seen in the outpatient clinic at 6-8 weeks after surgery. At this visit, the spica cast is removed by the orthopaedic technologists and an X-ray will be taken to ensure the hip has stayed in the joint. 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, which is normal. Physiotherapy is not usually required after open reduction surgery. Your orthopaedic team will give you lots 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 after cast removal. 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 dislocated hips treated with surgery 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.
Complications of open-reduction 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 very 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 very 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 is 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.
Re-dislocation
There is also the possibility that the hip may re-dislocate, meaning the ball may not stay in the hip socket and may come back out of joint. This complication is very rare, occurring in less than 2% of cases. If re-dislocation occurs, the doctor will discuss further treatments and surgical procedures that may be necessary to put the hip back in the joint, such as another open reduction or a hip osteotomy.
Growth disturbance (Avascular necrosis)
In approximately 5% of open reduction 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.