Mr. Hashemi-Nejad, Consultant Orthopaedic Surgeon at the Royal National Orthopaedic Hospital, has explained the main surgery options to treat DDH:
The term “closed reduction” implies that the capsule of the joint (the envelope that holds the hip), is not opened and, although there may be an incision to lengthen the tight muscle, the hip itself is not disturbed.
A closed reduction is undertaken any time after the age of three months up to one year, although some surgeons may consider this up to 18 months. This entails an examination under a general anaesthetic and is usually combined with dye being injected into the hip so that the ball can be seen reducing into the socket. If the ball sits nicely into the socket this may be combined with a small incision in the groin to release the contracted muscles and lengthen them to reduce the risk of blood supply damage to the ball. The child then goes into a cast. The time spent in the cast varies from six weeks and then use of a hip brace, which continues for nighttime and naptime bracing, depending on how the socket develops. Some surgeons use a cast for three months and occasionally this is in addition to change of plaster at the six-week mark.
On some occasions, the surgeon may recommend that the hip is too high out of the socket for a closed reduction, or if closed reduction has failed, in which case they may recommend open reduction.
An open reduction can be done through a groin incision, which is known as a medial open reduction. This releases or lengthens some of the tendons on the inner aspect of the thigh, the capsule is then opened and the ball is eased into the socket. The protocol, thereafter, is the same as a closed reduction.
There is no opportunity to do any tightening of the capsule, which is the envelope that holds the hip, or indeed any bony surgery at the time of medial open reduction (yes, this is the right term even if it sounds a bit odd). Some authorities believe that medial open reduction has a slightly higher risk of blood supply damage (avascular necrosis). Most people do not do a medial open reduction after the age of one. There are a few surgeons who would consider doing this up to the age of 18 months.
An open reduction through the front of the hip (anterior approach) is the standard way of addressing a dislocated hip. This allows lengthening the contracted muscles. The capsule (the envelope surrounding the hip) is opened, the hip is reduced and any obstruction to the reduction is removed. The capsule is then overlapped, (double breasted), to give more stability to the hip. At this stage, the surgeon may decide whether bony surgery is require to stabilise the hip further. This may involve bony surgery on the thigh bone, known as femoral osteotomy, or bony surgery on the acetabular side (pelvic osteotomy). The child is usually placed in a hip plaster for six-eight weeks.
A femoral osteotomy is the cutting of the thigh bone below the hip to ensure that the hip is stable in the socket. This can be done at an early age, any time after the age of one year or 18 months, but may also be done at an older age if the hip is not sitting well within the socket and there is a structural abnormality in the thigh bone. The surgeon can cut the bone so they can rotate the bone into the socket or tilt the bone into the socket and the bone is then held with a metal plate and screw. Generally speaking under the age of five, this would be augmented with a plaster because of the child’s inability to co-operate with the use of crutches. Over the age of five or six, the surgeon may not use a plaster. The surgeon may also tell you that the plate will be removed at a later date.
In hip dysplasia, the socket of the hip is usually not formed very well. It can grow normally following closed reduction or open reduction if the hip is stable. Occasionally, however, surgery on the pelvis is needed to re-orientate the socket.
The pelvic bone is sometimes referred to as the innominate bone and Dr. Salter, from Toronto, described an osteotomy (cutting of the bone) in 1960. “This is a cut in the bone above the socket and the surgeon can then re-orientate the socket to give improved coverage at the front and the side of the hip to stabilise the ball within the socket.”
The surgeon quite often uses some sort of fixation, either dissolvable pins or non-dissolvable metal work. Again under the age of five or six, Plaster of Paris is used, after the age of five or six the surgeon may choose not to use plaster. The surgeon will recommend removal of metal work at some point in the first year.
When the socket is quite large, a Pemberton osteotomy, which is again a type of surgery on the pelvic bone, is undertaken. This allows more redirection and also partial closure of an enlarged socket so that it captures the femoral head. It can be fixed with metal work or occasionally surgeons use bone graft to hold the position of the cup bone. Usually under the age of six, this is combined with a hip Spica.
A Chiari osteotomy is not usually done at a very young age and it is mainly a later operation. This is undertaken in an older child or an adult where the socket is quite shallow and the hip is irreducible so the socket is not amenable to redirection. If the socket was amenable to redirection the surgeon may suggest a triple or pelvic osteotomy or a periacetabular osteotomy, which are evolutions of the Salter osteotomy with further cuts around the socket to re-orientate the socket.
However, if the hip is not reducible in the socket and the socket is very shallow, an angled cut is made above the socket and the socket is displaced inwardly and the top of the pelvic bone is moved out to give a buttress to the acetabulum. This procedure is very similar to a shelf acetabuloplasty, which some surgeons use to give a buttress to a very shallow socket in order to try and hold the femoral head within the acetabulum.