Abstract
Introduction: A criticism of innominate osteotomy (IO) is that it causes relative acetabular retroversion, predisposing to OA. This study was designed to address this hypothesis.
Materials and Methods: We had access to radiographs of 30 patients 45 years after they had undergone open reduction and innominate osteotomy for late presenting DDH. Using the validated method of Hefti (1995) we measured anterior and posterior acetabular coverage, contact area and version.
Results: Group 1 – 26 Post-op hips, Group 2 – 20 Contralateral hips, Group 3 – 21 Normal hips. Anterior coverage was 10.8% in group 1, 11.0% in group 2 and 12.0% in group 3. Posterior coverage was 18.8% in group 1, 18.9% in group 2 and 21.0% in group 3. Contact area was 16.1 cm2 in group 1, 13.9 cm2 in group 2, and 22.1 cm2 in group 3. Version was 7.20 in group 1, 7.10 in group 2, and 7.70 in group 3.
A significant difference was found for contact area (p< 0.001). There was no significant difference in version (p = 0.845).
Conclusion: Early OA may be related to contact area. Any abnormal (retro)version grows out. Innominate osteotomy before the age of 5 years has the potential to facilitate, or at least not prevent, normal acetabular development and version.
The abstracts were prepared by Mr D J Bracey, Editorial Secretary. Correspondence should be addressed to him at Royal Cornwall Hospital, Treliske, Cornwall TR1 3LJ, England.
