We believe a curved periacetabular osteotomy is indicated for treatment of severe dysplastic hips with center-edge angles less than 0°, classified as Severin Group IV-b. However, the lower limit of the center-edge angle in hips classified as Severin Group IV-b is not clearly defined to determine which patients should receive periacetabular osteotomy alone.
We retrospectively compared the results of curved periacetabular osteotomies performed for the treatment of severe (Severin Group IV-b: center-edge angle < 0°) and moderate (Severin Groups III and IV-a: center-edge angle ≥ 0°) dysplastic hips. We investigated the lower limit of the center-edge angle, which was corrected by a curved periacetabular osteotomy alone in Severin Group IV-b hips.
We divided 191 hips in 163 patients into moderate (147 hips) and severe (44 hips) dysplastic hip groups. Minimum followup was 2 years (mean, 70.9 and 70.6 months, respectively). Clinical evaluations were performed using the Harris hip score. Radiographic measurements included the center-edge angle, acetabular head index, acetabular roof obliquity, and head lateralization index. Complications were compared between the two groups.
All clinical and radiographic postoperative parameters showed satisfactory improvement over the preoperative parameters in both groups. The postoperative acetabular roof obliquity and head lateralization index were equivalent between the two groups. Eleven hips deteriorated to end-stage osteoarthritis. No complications were specifically associated with the severe dysplastic hips.
Curved periacetabular osteotomy alone for treatment of severe dysplastic hips with preoperative center-edge angles as low as -20° and classified as Severin Group IV-b restored weightbearing area and medialization.