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Hip

CAN WE IDENTIFY THRESHOLDS FOR REVISION SURGERY IN METAL-ON-METAL HIP ARTHROPLASTY PATIENTS WITH ADVERSE REACTIONS TO METAL DEBRIS? A RETROSPECTIVE COHORT STUDY OF 346 REVISIONS

The British Hip Society (BHS) Meeting, Nottingham, England, 27 February – 1 March 2019.



Abstract

Introduction

We investigated predictors of poor outcomes following metal-on-metal hip arthroplasty (MoMHA) revision surgery performed for adverse reactions to metal debris (ARMD), to help inform the revision threshold and type of reconstruction.

Patients and Methods

A retrospective cohort study was performed involving 346 MoMHAs revised for histologically confirmed ARMD at two specialist centres (245=hip resurfacing, 101=total hip arthroplasty). Numerous preoperative (blood metal ions and imaging) and intraoperative (findings, and components removed/implanted) factors were used to predict poor outcomes. Poor outcomes were postoperative complications (including re-revisions), 90-day mortality, and poor Oxford Hip Scores (<27/48). Multivariable logistic regression models for predicting poor outcomes were developed using stepwise selection methods.

Results

Cumulative implant survival rate seven-years after ARMD revision was 87.0% (95% CI=81.0%-91.2%). Poor outcomes occurred in 39% (n=135). Shorter time (under four-years) from primary to revision surgery (odds ratio (OR)=2.12, CI=1.00–4.46) was the only preoperative predictor of poor outcomes. Pre-revision metal ions and imaging did not influence outcomes. Single-component revisions increased the risk of poor outcomes (acetabular or femoral vs. all component revisions; OR=2.99, CI=1.50–5.97). Intraoperative factors reducing the risk of poor outcomes included the posterior approach (OR=0.22, CI=0.10–0.49), revision head sizes ≥36mm (vs. <36mm: OR=0.37, CI=0.18–0.77), ceramic-on-polyethylene (OR vs. ceramic-on-ceramic=0.30, CI=0.14–0.66) and metal-on-polyethylene revision bearings (OR vs. ceramic-on-ceramic=0.37, CI=0.17–0.83).

Discussion

This large cohort study demonstrated 39% of patients experience poor outcomes following MoMHA revision for ARMD. This information will help surgeons when counselling patient's pre-revision about the expected prognosis. No threshold exists for recommending ARMD revision, therefore surgeons must make decisions on an individual case basis. However, surgeons can make intraoperative decisions that influence outcomes following ARMD revision.

Conclusion

We recommend optimal outcomes following ARMD revision may be achieved if surgeons use the posterior approach, revise all MoMHA components, and use ≥36mm ceramic-on-polyethylene or metal-on-polyethylene articulations.


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