INNOMINATE OSTEOTOMY WAS ASSOCIATED WITH BETTER ACETABULAR REMODELLING AND HIP STABILITY THAN VARUS OSTEOTOMY AFTER OPEN REDUCTION OF A DISLOCATED HIP

Abstract

Aim: To compare acetabular development and hip stability over time in patients treated for developmental dysplasia of the hip (DDH) by open reduction combined with either varusderotation (VDRO) or innominate (IO) osteotomies.

Method: Patients who underwent open reduction for DDH, combined with either VDRO (38 patients) or IO (33 patients), between 15 months and 4 years of age were reviewed. Both groups comprised a single surgeon consecutive series, differing only in the type of osteotomy performed. A total of 490 postoperative radiographs over a maximum follow-up period of 13.6 years were analyzed. We used repeated measures analysis of variance to compare the change in acetabular index (AI) as well as several other radiographic indices of acetabular development and hip stability over time.

Results: After osteotomy, the AI decreased in both groups but the magnitude of the decrease was significantly different between groups over time (p< 0.0001). The AI of patients undergoing VDRO never decreased as much as that of patients undergoing IO, with a mean difference of 10.4 degrees after 4 years (p< 0.0001). Similarly the IO group demonstrated more favourable acetabular architecture and hip stability over time compared to the VDRO group, as quantified by change in the acetabular floor thickness (p< 0.03), lateral centring ratio (p< 0.0001) and superior centring ratio (p < 0.0001).

Conclusions: Acetabular remodelling after IO was more effective at reversing acetabular dysplasia and maintaining hip stability than VDRO. Long-term follow-up of VDRO will be necessary to determine if late improvement occurs. IO may be preferable over VDRO in the treatment of hip dislocation after walking age.