Modified Chiari pelvic osteotomy: a long-term follow-up study.

In a series of 100 modified Chiari pelvic osteotomies in ninety-six patients, who were followed for an average of nine years and three months (range, six years to fourteen years and eight months), an excellent or good clinical result was obtained in seventy-eight hips. The level of the osteotomy line on postoperative radiographs was compared with the clinical result. The average clinical result was good in seventy-four (84 per cent) of the eighty-eight patients in whom the osteotomy was at the I-I, I-II, or II-II level, according to the classification of levels by Azuma et al., but was good in only four of the twelve patients in whom the osteotomy was at another level (p = 0.0003). We found that smooth anterior and lateral coverage can be obtained by the use of a dome-shaped osteotomy line.