EARLY REVISION FOR CEMENTED & CEMENT-LESS PRIMARY TOTAL HIP ARTHROPLASTY: AN ANALYSIS OF THE NEW ZEALAND JOINT REGISTRY

Abstract

Recent analysis of the Australian Joint Replacement Registry revealed the rate of revision of primary total hip arthroplasty was greater with cement-less fixation than with cemented fixation. The seven-year results of the New Zealand Joint Registry have also shown an increased revision rate with cement-less hip arthroplasty. The purpose of this study was to review the revision rate of cemented and cement-less total hip arthroplasty from those joint replacements registered with the New Zealand Joint Registry and to determine the cause for revision.

All 42 1000 primary total hip arthroplasties recorded in the New Zealand National Joint Registry since its establishment in 1999, until December 2006, were included in the study. The rate of revision of cemented and cement-less femoral and acetabular components was calculated for the study period, and for the first 90 days after the operation. The reasons for revision were evaluated and compared for different methods of fixation. Survival curves were constructed for each combination of femoral and acetabular component fixation.

Two hundred and eighty three cement-less (2.46%), 294 cemented (1.91%), and 321 cemented femoral with cement-less acetabular fixation (2.19%) primary total hip arthroplasties have been revised. The difference in revision rate between each group was statistically significant. There were only 573 primary total hip arthroplasties performed with cement-less femoral and cemented acetabular component, with 11 revised. The rate of revision was highest in the cement-less group (0.74% revised per year), and lowest in the cemented group (0.47%).

The predominant reason for revision in all three major groups was dislocation. Revision for loosening of the acetabulum was more common with cemented fixation. Revision for fractured femur was more common with cement-less fixation, and revision for deep infection was most common in the cemented group. These differences were all shown to be statistically significant. Revision for loosening of the femoral component and pain was more common in the cement-less group, but was not shown to be statistically significant.

In the first 90 days, there were a large number of revisions in the cement-less group (0.77%), compared to the cemented group (0.32%), and cemented femur with cement-less acetabulum group (0.57%). Dislocation was again the most common reason for revision. Revision for fractured femur was high in the cement-less group (0.19%) in the first 90 days. Excluding these early revisions, the number of revisions in the cemented and cement-less groups maintained a similar rate for the remainder of the study period.

This study confirmed that the revision rate for uncemented THA was higher than for cemented THA. The major difference was the early revision rate within 90 days. Addressing these problems would improve the overall early outcome.