POINT: Early intervention is appropriate in most instances of residual DDH.
Dennis R. Wenger, MD
The need for intervention—specifically for performing early pelvic osteotomy in young children with radiographic evidence of developmental dysplasia of the hip (DDH)—may be dictated by signs and symptoms. The decision in favor of early osteotomy is easy if the patient has abnormal-looking radiographs, exhibits symptoms, and has a break in Shenton’s line, representing hip subluxation or dislocation as opposed to acetabular dysplasia.
Shenton’s line is a radiographic feature—an imaginary line drawn along the inferior border of the superior pubic ramus (superior border of the obturator foramen) and along the inferomedial border of the neck of the femur. In a normal hip, the line is continuous and smooth.
Traditionally, when we reviewed radiographs of an asymptomatic patient with visual signs of DDH, we might say that the patient would probably do pretty well over time. We would simply wait and watch it.
The decision to perform an early osteotomy can seem difficult because the hip can improve over time. But the results are not as good when surgery is performed in teenagers. The patient may drop out of the system or the shape of the femoral head or the acetabulum may change, making surgery more difficult. We can operate early, even if the patient has no symptoms, or we can wait and see, possibly performing more complicated surgery later. I have emphasized the ease of the operation on the child who is 5 to 10 years old; it has fewer complications and allows for joint ‘remodeling.’
In addition, most pediatric orthopaedists can perform surgeries such as the Salter osteotomy or the Pemberton procedure. The joint remodeling is extraordinarily important. The femoral head tends to change its shape over time, and the earlier you can get the femoral head covered over the hip, the better the results are likely to be. You will avoid having to open the joint as part of an acetabuloplasty.
Experience with procedures in teenagers who did not undergo surgery at a young age has shifted opinion in favor of earlier intervention. Teenage patients with DDH who did not undergo surgery at a young age may have residual dysplasia or experience a sudden onset of pain.
We know the skeletal complications of traditional acetabuloplasties performed in teenagers. More recently developed procedures, such as the periacetabular osteotomy (PAO), may increase the risk of vessel injury, nerve injury, heterotopic bone formation, and other problems.
Many surgeons who treat teens with residual DDH are now opening the hip capsule to reshape the head. The philosophy has changed. Previously, we only treated patients who had symptoms. Today, we analyze all patients and, particularly if there is a break in Shenton’s line, we do early surgery.
When surgery is performed, either the Salter or the Pemberton procedure is acceptable. I believe that normalization of the hip radiograph by age 6 or 8 years is within the realm of almost all pediatric orthopaedic surgeons and gives the patient the best chance for normal function over time.
Should we treat a patient with no pain and with no symptoms? In the 1960s and 1970s, the answer was no; now it is yes. It depends on the surgeon’s skills. Teenage surgery requires someone with experience in doing more complex procedures.
Dennis R. Wenger, MD, is in private practice at the Pediatric Orthopaedic and Scoliosis Center in San Diego, Calif. Disclosure information: OrthoPediatrics, Rhino Pediatric Orthopaedic Designs, Wolters Kluwer Health - Lippincott Williams & Wilkins, Journal of Pediatric Orthopedics, Journal of Children’s Orthopedics.
COUNTERPOINT: Surgery should generally be reserved for patients with symptoms.
Young Jo Kim, MD
I admit that, in some circumstances, early pelvic osteotomy for DDH is indicated. If the hip is unstable, it will not remodel and the acetabular index will not improve. Several radiographic features can be used to detect instability, including a break in Shenton’s line. With the evolution of modern pelvic osteotomy techniques, surgery can be safely performed in a symptomatic patient.
But I challenge the rationale for surgically treating an asymptomatic hip in a young patient based on radiographic findings. If the hip is stable, we are really treating a radiographic metric or surrogate—the acetabular index—that can be inaccurate and may not represent the true acetabular morphology.
Acetabular remodeling occurs up to 4 years after reduction is performed in the very young patient. After age 3, acetabular remodeling is unpredictable. If the acetabular index is 28 degrees at 4 to 6 years after reduction, the chance of having acetabular dysplasia is almost 80 percent.
The question is, what is the real acetabular index? The radiographic measure can be unreliable. It will vary based on how the radiograph is obtained. How reliable is the acetabular remodeling natural history data? The very basic metric on which the decision to perform surgery is made may be inaccurate.
For example, I once performed bilateral open reduction with femoral osteotomies on a young (2½-year-old) patient, but did not perform simultaneous pelvic osteotomies. My decision was heavily criticized. But by the time the patient was age 14, radiographs showed healthy hips. If I had performed an osteotomy when the patient was 5 years old, would I have made the hip have too much coverage? Would she have impingement? I don’t know.
In another case, a 3-year-old patient had an elevated acetabular index after open reduction. But the MRI showed a cartilaginous acetabulum, and the hip was stable. Over time, it is ossifying and will end up being normal.
With modern pelvic osteotomy, we can safely correct both moderate and severe dysplasia. I would submit that treating truly symptomatic patients with problems at maturity will result in less overtreatment and more precise treatment. Treating residual acetabular dysplasia in immature hips is prophylactic treatment based on an understanding of the natural evolution of hips. In these situations, the surgeon must be sure that the radiographic surrogate used to make the decision is accurate and that the natural history of the patient’s hip is well understood.
I recognize that acetabular surgery at a young age is safer and allows normalization of future growth. In the end, I don’t think we disagree too much. If the hip is unstable with a broken Shenton’s line and a wide tear drop, an early acetabular procedure to stabilize the hip is necessary.
If the hip is stable, acetabular remodeling can occur up to 4 years after reduction. If the acetabular index remains elevated above 28 degrees, the probability that the acetabulum will remain dysplastic at maturity is high; however, this does not mean these hips will be symptomatic. If the resultant acetabular dysplasia at maturity is going to be mild and the family is uncertain, the dyplasia can be treated with a pelvic osteotomy at maturity.
Young Jo Kim, MD, is associate professor of orthopaedic surgery at the Harvard Medical School and director of the adolescent and young adult hip program at Children’s Hospital Boston. Disclosure information: Synthes, Siemens Health Care, Osteoarthritis and Cartilage, POSNA.