Abstract
Background: Revision total hip replacement in patients with a previous diagnosis of developmental dysplasia of the hip (DDH) can be a challenging and technically demanding procedure. Two of the major concerns are deficient acetabular bone stock and the position of the acetabular implant, particularly if the hip centre was not restored during the primary procedure. The purpose of this study was to determine if cup height, lateralization or abduction angle are correlated with functional outcome or survivorship in revision total hip replacement (THR) in patients with a previous diagnosis of DDH.
Methods: A retrospective investigation of 51 sequential patients (63 hips) previously diagnosed with DDH who underwent revision THR at our center between 1984 and 2000 was performed. The mean duration of follow up was 119 months (range 36 to 238 months). Forty-one patients (52 hips) were available for functional outcome and survivorship analysis. The remaining ten patients (11 hips) were available only for survivorship analysis. Three independent variables identified apriori as possible correlates were cup height, lateralization and angle as measured on the AP radiographs. Functional outcome measurement consisted of the Harris Hip, SF36 and WOMAC questionnaires. Linear regression analysis and Kaplan-Meier curves were used to determine if any of the variables correlated with functional outcome or survivorship.
Results: Cup height was found to have a statistically significant (p< 0.05) correlation with Harris Hip, SF36, and WOMAC functional scores. High hip centers correlated with worse scores. In addition, patients with hip centers less than 3.5 cm above the radiographic tear drop had a statistically significant improvement in cup survivorship compared to those with higher hip centers.
Conclusion: Restoration of hip center height to as close to the radiographic teardrop as possible improves functional outcome and cup survivorship.
The abstracts were prepared by Orah Naor, IOA Co-ordinator and Secretary. Correspondence should be addressed to Israel Orthopaedic Association, PO Box 7845, Haifa 31074, Israel.
