The results of Chiari pelvic osteotomy in adolescents with a brief literature review

Abstract

Purpose: Chiari medial displacement osteotomy is a procedure that uses the cancellous bone of the ilium to contain the femoral head and bear weight. It is the most contraversial osteotomy of the hip joint. This study was therefore conducted to determine the results of this osteotomy with mid-term follow-up in children.

Methods: From 1995 to 2004, 20 Chiari pelvic osteotomies (in 18 patients) were performed. There were 15 male and 3 female patients. The average age at operation was 12.6 years and the mean follow-up was 54 months. The operative technique was as described by Chiari. An iliofemoral approach was used without utilizing a traction table. If there was anterior or anterolateral uncoverage of the femoral head, bone graft augmentation was performed.

Results: The angle of the osteotomy averaged 12 degrees , with the distance from the acetabulum averaging 3.2 mm. The average displacement was 42%. Of the 20 Chiari osteotomies, 11 were categorized as excellent, 8 as good and one as fair in terms of clinical and radiological results. Student's t test statistics showed improvements in all radiologic parameters of the hip joint (Sharp angle, center-edge angle and coverage of the femoral head). Graft resorption was observed in 25% of the patients.

Conclusion: There are very rare indications of Chiari osteotomy in patients younger than 10 years. Because of the high rate of graft resorption, Chiari osteotomy should be the last treatment option when there is anterior or anterolateral uncoverage of the hip joint.

Fig. 1

Radiographic parameters of Chiari osteotomy. Angle of Chiari (α), the angle between the line parallel to the reference line (intertear drop line) and the osteotomy line. Displacement = line A/line B × 100

Fig. 2A–D

A 9.5-year-old boy with Perthes’ disease, who had been operated at the age of eight with varus osteotomy of the proximal femoral bone. Eighteen months later, Chiari osteotomy and bone graft augmentation was performed for coxa magna and extruded femoral head (A–C); the nine-year follow-up radiograph showed complete resorption of the bone graft and uncoverage of the femoral head (D)