To what extent does remodeling of the proximal femur and the acetabulum occur between disease healing and skeletal maturity in Perthes disease? A radiological study.

Radiographs of 75 children with unilateral disease were studied to quantify the extent of remodeling of the proximal femur and the acetabulum between healing and skeletal maturity in children with Perthes disease. The mean ages at disease onset, healing, and skeletal maturity were 8.3, 11.9, and 15.5 years, respectively. Fifty-seven children were treated surgically by subtrochanteric varus osteotomy with trochanteric epiphyseodesis; the remaining 18 children were treated nonoperatively. Assessment of the Mose's index and Stulberg grading and measurements of the proximal femur and the acetabulum were made at healing and at skeletal maturity. The Stulberg grade and the Mose's index did not change between healing and skeletal maturity in 88% and 95% of children, respectively. In operated children, there was significant improvement of the articulotrochanteric distance, acetabular depth, neck-shaft angle, and Sharp's angle between disease healing and skeletal maturity, but no such changes occurred in children who were not operated on. We conclude that because little change occurs in the shape of the femoral head and congruity of the hip between healing and skeletal maturity, the outcome of treatment based on these 2 variables can be assessed once the disease heals in children with late-onset Perthes disease.