Ultimately, the long-term prognosis for Perthes depends on the mechanical shape of the femoral head as it interfaces to the acetabulum (hip joint). However, the final mechanical interface won’t be known until the disease runs through the lengthy repair process that can last up to 5 years after the loss of blood supply episode. The short-term problem confronting orthopedic specialists is that they need to examine the hip very early in the process and they need to estimate the final mechanical configuration and then make an informed judgment about the necessity and type of treatment.
The best method to estimate the prognosis for the patient can be used very early in the disease process (only a few months after the loss of blood episode). This prediction technique is based on two pieces of information: the age of the child at onset and the degree of necrotic bone involvement within the femoral head. The older the child when diagnosed, the worse the prognosis. Children under the age of six have the best prognosis even without treatment. For children over age six, the best prognosis is before the age of eight. The prognosis worsens between ages eight and ten and is often quite poor after the age of ten. The relationship between age at onset and prognosis is widely agreed upon by pediatric orthopedic surgeons.
The other major prognostic factor is the extent of femoral head involvement. The smaller the amount of femoral head involved (with loss of blood supply), the lower the risk of long-term femoral head deformation. The simplest classification system for Perthes, the Salter-Thompson classification, divides cases into “partial” vs. “whole head” involvement which corresponds to less than and greater than fifty percent of the head affected, respectively. Obviously, the prognosis is better with partial head involvement than with whole head involvement. Most pediatric orthopedic surgeons agree that partial head involvement cases require no treatment, as the disease will correct itself.
All treatment for Perthes Disease have the same goal: return sphericity to the femoral head.
If your child is older and has greater than 50% head involvement, then treatment may be indicated. Treatment for Perthes can generally be divided into five categories:
- Range-of-motion (ROM) treatment
- Core Decompression
- Containment Treatment
- Distraction Treatment
- Femoral Head Reshaping