Preliminary results of an anteverting triple periacetabular osteotomy for the treatment of hip instability in Down syndrome

PURPOSE: To investigate the outcomes of an anteverting triple periacetabular osteotomy for the treatment of hip instability in skeletally immature patients with Down syndrome. METHODS: We evaluated 16 patients (21 hips) with Down syndrome and hip instability who underwent an anteverting triple periacetabular osteotomy between 2007 and 2016. There were nine females and seven males with an average age of 7.4 years SD 2.0. We assessed the level of hip pain, gait ability and clinical stability at a minimum of one year after surgery. Radiographic evaluation included pre- and postoperative lateral centre-edge angle (LCEA), Tönnis acetabular angle and extrusion index. RESULT: After an average follow-up of 4.1 years SD 2.6, 20 of 21 hips (95%) remained clinically stable. In all, 12 of 16 (75%) patients had a full gait without a major limp, but three patients (19%) had a persistent limp. Of the 21 procedures, one hip (5%) was considered a failure due to persistent instability. There was a mean increase of 18.3º SD 15.3º of the LCEA (p < 0.001); a mean decrease of 15.2º SD 11.6º (p < 0.001) for the Tönnis angle and the extrusion index had a mean decrease of 0.27 SD 0.20 (p < 0.001). The most common complications were minor and included nonunion of the pubis or ischium (24%) and stress fractures of the pubis and ischium (14%). Only one patient required unplanned surgery for the treatment of an infection; which was considered a major complication. CONCLUSION: The anteverting triple periacetabular osteotomy provided global deformity correction and achieved hip stability in 95% of the hips after a mean follow-up of 4.1 years. LEVEL OF EVIDENCE: Therapeutic level IV.