Effects of Salter innominate osteotomy on the sacroiliac joint in patients with developmental hip dysplasia.

The pressure effects of Salter innominate osteotomy (SIO), a surgical treatment for developmental hip dysplasia (DHD), on the sacroiliac joint were investigated in a retrospective study. Pre- and post-operative direct anteroposterior pelvic radiographs of 60 cases with unilateral DHD treated by SIO were examined. The mean age at surgery was 27.7 months (range 18-48 months). The distance from the posterior inferior iliac spine to the midline (from the middle of the first sacral vertebra to the symphysis pubis) was measured. No difference was found between pre- and post-operative distances on the normal, non-operated side. On the operated side, no change was observed in 10 cases (16.7%), but the distance increased by 2 mm or 3 mm in 50 cases (83.3%) post-operatively. This increase was statistically significant, but not related to age at surgery. These findings indicate that SIO creates pressure on the inferior part of the sacroiliac joint, resulting in some displacement. Such irreversible changes may eventually lead to joint degeneration and pain.