Long-term follow-up of Chiari pelvic osteotomy in myelomeningocele.

The management of hip instability in myelomeningocele patients is controversial. The purpose of this study is to review our long-term results of isolated Chiari osteotomies in the treatment of hip instability in children with myelomeningocele. Between 1975 and 1988, 11 patients underwent 13 Chiari osteotomies for reducible hip subluxation or dislocation and acetabular deficiency. The patients returned for follow-up clinical examinations, interviews, and radiographs. The average age at the time of surgery was 9.4 years (range, 5-18). The average age at follow-up was 18 years (range, 13-23). The average follow-up was 11.4 years (range, 2-18). The mean preoperative center-edge (CE) angle was -38 degrees. The mean immediate postoperative CE angle was 41 degrees. At final follow-up, the mean CE angle was 4.6 degrees. Only three of the 10 hips had a normal CE angle of > or = 25 degrees. The Chiari osteotomy alone did not achieve long-term hip stability in the majority of patients. Several, if not most, of our patients may progress to frank dislocation with longer follow-up.