Results of 11 cases treated with Chiari pelvic osteotomy were reported. Average age of patients at operation were 38 years and follow up periods after surgery were 6 years and 2 months. In all cases, plastic effects for acetabular edge were satisfactory; average CE angle improved to 31° from -7°, Sharp angle to 39° from 49° and acetabular head index to 93% from 50%. Ten of 11 cases have shown successful results, but one case was unsuccessful. Four cases of early stage and another 4 cases of progressive stage have gained excellent results; they have complained of no or very slight hip pain and have gained good ROM and ADL. Two cases of progressive stage have gained good results by combined operation with valgus osteotomy of the femur; they have complained of slight hip pain and of slight limitation of ROM and ADL. One case of progressive stage have shown unsatisfactory result and THR was performed as revision operation after 6 years. In successful 10 cases, pelvic osteotomy were carried out at about 5mm upward from acetabular margin. On the other hand, in the unsuccessful case the osteotomy was carried out at too low level (3mm upward from acetabular margin).
