Metal on Metal No factors proved helpful in predicting outcomes of THA revision for ARMD


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Jun 8, 2007
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No factors proved helpful in predicting outcomes of THA revision for ARMD
(adverse reaction to metal debris)
Orthopaedics Today Europe, August 2016

GENEVA — Finnish researchers found no preoperative factors helped predict which patients would have a poor result following total hip arthroplasty revision for adverse reaction to metal debris, according to findings presented at the 17th EFORT Annual Congress, here.

Olli Lainiala, MD, PhD, and colleagues at Coxa Hospital for Joint Replacement in Tampere, Finland, used a multivariable analysis to study preoperative factors that might be related to total hip arthroplasty (THA) revision outcomes in patients with adverse reaction to metal debris (ARMD). The factors they looked at included patient age and gender, implant type and size of femoral head, preoperative cobalt and chromium levels in the blood and findings on preoperative imaging.

“None of the variables studied predicted the decrease of Oxford Hip score [OHS] pain subscore. And, the function subscore results were much similar — no significant differences in any of the variables studied,” Lainiala said.

Focus on Oxford Hip score subscales
Lainiala and colleagues included in their study 107 patients at their institution who underwent primary THA with an ASR XL (DePuy Synthes) prosthesis with a large-size head and were advised they had ARMD. Six orthopaedists performed the revision surgeries, all of which were done through a posterior approach. The investigators focused primarily on the OHS pain and function sub-scores for this study, both of which use a scale of 0 to 100. They defined a minimal detectable change in each score as 10 points.

Five patients required a re-revision procedure. One patient died before the study’s 1-year follow-up was completed. Of the remaining 101 patients, 89 patients needed an OHS for ultimate inclusion in the analysis portion of the study.

“There was no clinically significant increase or decrease in the median pain sub-score or function sub-score,” Lainiala said.

Investigators observed, however, there were decreases of about 10 points in the pain and function sub-scores in 16 patients and 17 patients, respectively

No differences in pain scores
According to findings from the multivariable model that was used, the pain scores were no different among patients who underwent a revision based on gender, age, bearing surface and femoral stem used during revision surgery, head size, preoperative imaging results or preoperative metal ion levels.

Lainiala and colleagues were able to follow up on 88% of these patients. But, he noted in his presentation, a limitation of the study was the missing OHS findings.

“It is known that usually it is the patients [who are] doing worse who do not return the questionnaires. So that is definitely a limitation,” he said.

The fact that different surgeons performed the revisions and used a variety of implants another possible weakness of the study, Lainiala noted.

“We think the answer to the question [of] who should go through a revision might not be answered by studying the patients who have already gone through the revision. What we should do instead [is] study those who have not been revised, but have been diagnosed as potential or definite, and see how they do in the follow-up,” Lainiala said. – by Susan M. Rapp

Lainiala O, et al. Paper #2483. Presented at 17th EFORT Annual Congress — A combined programme in partnership with swiss orthopaedics; 1-3 June 2016; Geneva.


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