A retrospective study of 22 Chiari osteotomies in 21 children with severe Legg-Calve-Perthes disease is presented. All cases were studied at skeletal maturity. The average age at surgery was 8.5 years with an average follow-up of 6.1 years. Four hips were classified as Catterall group III and the remaining hips as group IV. Arthrography was used preoperatively to measure the femoral head sphericity, the femoral head coverage and the eccentric index. The same parameters were studied on radiographs at skeletal maturity.