Effect of prophylactic trochanteric epiphyseodesis in older children with Perthes' disease.

To evaluate the effect of prophylactic epiphyseodesis of the greater trochanter in Perthes' disease, 62 children with unilateral Perthes' disease who underwent trochanteric epiphyseodesis combined with varus osteotomy of the femur during the active stage of the disease (mean age at surgery: 8.4 y) and 20 controls were followed up until skeletal maturity. On radiographs taken at skeletal maturity, the articulo-trochanteric distance, the center-trochanteric distance, the length of the abductor lever arm, the neck-shaft angle, the radius of the femoral head, and the Reimer's migration index of normal and affected hips were measured. The shape of the femoral head was assessed according to the criteria of Mose. The range of hip motion, the strength of hip abduction, and limb lengths were measured and the Trendelenburg sign was elicited. The mean values of articulo-trochanteric distance and center-trochanteric distance were greater and the frequency of a positive Trendelenburg sign was less in children who had undergone trochanteric epiphyseodesis than in children who had no surgery (P<0.01). Trochanteric epiphyseodesis achieved optimal trochanteric growth arrest in 60% of operated children; the procedure was not effective in 30%, and in 10% of children there was overcorrection. Logistic regression analysis showed that the size of the femoral head at healing and the age at surgery were variables that significantly influenced the effectiveness of trochanteric growth arrest. At skeletal maturity, the mean shortening of the affected limb in operated children was 0.44 cm (SD 0.68 cm), whereas that of non-operated children was 0.86 cm (SD 0.78 cm) (P<0.05). The range of motion of the hip was excellent and there were no significant differences in the range of motion among children with optimal correction, under-correction, and overcorrection. A probability curve plotted on the basis of a logistic regression model suggests that effective trochanteric arrest may be achieved in a high proportion of children operated at or before 8.5 years of age and in half the children operated between the age of 8.5 years and 10 years. On the basis of this study, we recommend prophylactic epiphyseodesis of the greater trochanter as a means of minimizing trochanteric overgrowth and resultant Trendelenburg gait in older child with Perthes' disease.