SURVIVORSHIP AND FUNCTIONAL OUTCOME OF REVISION HIP ARTHROPLASTY IN PATIENTS WITH A PREVIOUS TOTAL HIP REPLACEMENT FOR DEVELOPMENTAL DYSPLASIA OF THE HIP.

Abstract

This is a retrospective study of fifty nine hips in fourty nine patients with a previous total hip replacement for developmental dysplasia of the hip who underwent a revision arthroplasty of the hip. Fifty three patients were available for follow up. Radiographs and charts were reviewed and functional outcome scores were obtained in order to determine if a correlation existed between cup position and functional outcome and survivorship. Cup height was found to be a statistically significant predictor for functional outcome and cup survivorship.

To determine if cup height, lateralization or angle are correlated with functional outcome or survivorship in revision total hip replacement (THR) in patients with a previous THR for developmental dysplasia of the hip (DDH).

There is a paucity of literature correlating functional outcome with cup position in revision THR.

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.

A retrospective investigation of forty-nine sequential patients (fifty-nine hips) previously diagnosed with DDH who underwent revision THR at our center between 1984 and 2000 was performed. Forty-three patients (fifty-three hips) were available for survivorship analysis and thirty-five patients (forty-five hips) were available for functional analysis. The mean follow up was one hundred and eighteen months (range 36–230). 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.

Restoration of hip center height to as close to the radiographic tear drop as possible improves functional outcome. Placement of the cup to within 3.5 cm of the tear drop improves cup survivorship.