JOA - 2026-08-01 - Journal Article; Randomized Controlled Trial
Ten-Year Outcomes of Hypoallergenic Coated and Standard Implants in Total Knee Arthroplasty: A Randomized Controlled Trial.
Roitzsch C, Beyer F, Lützner C, Postler AE, Lützner J
Topics
Key Takeaway
At 10-year follow-up, hypoallergenic-coated and standard TKA implants demonstrated identical 98% implant survival with no significant difference in Oxford Knee Score, SF-36, or serum metal levels.
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Summary
This RCT compared 10-year outcomes of hypoallergenic-coated versus standard TKA implants in patients without known metal allergy undergoing unconstrained primary TKA. Both groups achieved 98% implant survival with one revision each, and showed no significant differences in Oxford Knee Score, SF-36, or patient satisfaction at 10 years. Serum metal ion levels were below detection limits in both groups at 5 years, with no between-group difference.
Key Limitation
Exclusion of patients with confirmed metal allergy means the study cannot answer whether coated implants outperform standard implants in the highest-risk, allergy-confirmed population for whom coating is most clinically justified.
Original Abstract
BACKGROUND
Patients who have metal allergies frequently request hypoallergenic implants. In total knee arthroplasty (TKA), coating of standard implants is commonly used, with almost 10% of all primary TKAs in Germany in 2023. Registry data, however, have shown increased revision rates for coated implants. Whether this is due to the coating itself or the characteristics of allergy-prone patients remains unclear. The aim of this study was to compare revision rates, patient-reported outcomes, and serum metal levels in patients receiving coated versus standard TKA.
METHODS
In this randomized controlled trial, patients undergoing primary, unconstrained TKA were enrolled. Exclusion criteria included other metal implants, the need for constrained prosthesis, or known implant material allergy. A total of 118 patients were randomized (59 per group) to receive a coated or standard TKA. Serum metal levels were assessed up to five years. At the 10-year follow-up, 20 patients had died, and two had undergone revision. Of the remaining 96, 79 were available for clinical evaluation. Outcomes included the Oxford Knee Score, Short Form-36, and patient satisfaction.
RESULTS
Overall, 10-year implant survival was 98% for both groups. A revision occurred in each group. After 10 years, both groups showed good functional outcomes, health-related quality of life, and patient satisfaction, with no significant differences. However, functional scores and the physical component summary of the Short Form-36 declined compared to the 5-year follow-up, likely due to aging. Serum metal levels after five years were mostly below detection limits and similar across groups.
CONCLUSIONS
Both coated and standard TKA implants demonstrated sustained improvement in function and health-related quality of life, as well as low revision rates. In comparable patient cohorts, the use of this coated implant system does not appear to be associated with inferior outcomes.