Abstract
Introduction: A criticism of innominate osteotomy is that it causes relative acetabular retroversion, predisposing to osteoarthritis. This study was designed to address this hypothesis.
Materials and Methods: We had access to radiographs of 30 patients that had undergone open reduction and innominate osteotomy for late presenting developmental hip dislocation. The patients are now middle-aged and formed part of a previously reported study. Standardised, well-centered anteroposterior standing hip radiographs were obtained and using the validated method of Hefti (1995), anterior and posterior acetabular coverage and contact area were measured. From this we were able to extrapalate the acetabular version.
Ten operated hips had advanced osteoarthritis which made it impossible to identify acetabular landmarks.
Twenty-six hips were readable despite signs of mild to moderate osteoarthritis in some (Group A). 20 contra-lateral hips without DDH which appeared radiographically normal formed control group B. 21 further age and sex matched AP pelvis radiographs were taken from the PACS system at random. All of which had been reported as normal by a consultant musculoskeletal radiologist, these formed group C.
The Kruskal Wallis test was used to compare the 4 outcomes, in the 3 groups.
A significant difference between the groups was found for contact area (p< 0.001). There was no significant difference between the other 3 outcomes. Anterior coverage (p=0.509), posterior coverage (p = 0.135) and antirversion (p= 0.845).
Conclusion: Acetabular coverage and anteversion in hips with a good outcome after innominate osteotomy with open reduction were not different to a control group of radiographically normal hips without previous DDH. The early osteoarthritic changes seen in these hips may be related to a decreased contact area compared to the normal population. 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 Matt Costa and Mr Ben Ollivere. Correspondence should be addressed to Mr Costa at Clinical Sciences Research Institute, University of Warwick, Clifford Bridge Road, Coventry CV2 2DX, UK.
