Electromagnetic induction disinfection applied to cemented knee arthroplasty implants: safety evaluation of potential changes in the bone cement

Abstract

Background: Electromagnetic induction heating is a newly developed disinfection method aimed at improving periprosthetic infection outcomes after Debridement and Implant Retention (DAIR). One safety concern is its effect over polymethylmethacrylate (PMMA). The objective of this in-vitro study is to assess such effect on cement adjacent to metallic arthroplasty components. Methods: Two different PMMA products, with and without antibiotic, were applied on three total-knee arthroplasty implants. A portable device was used to administer induction-heating protocols: 70 °C, 3.5 min and 100 °C, 3.5 min, while the third prosthesis served as control. The 602 cm⁻¹ and 558 cm⁻¹ bands in Raman spectroscopy were used to assess isotactic and syndiotactic components of PMMA, while 1339 cm⁻¹, 1295 cm⁻¹ and 882 cm⁻¹ bands in infrared spectroscopy (ATR-FTIR) were used to assess crystallinity. Results: Isotactic/syndiotactic ratios were 0.27(±0.02) for antibiotic-free cement, and 0.41(±0.02) for gentamicin-loaded cement. After induction-heating protocols, isotactic fraction increased in antibiotic-free cement, and decreased in gentamicin-loaded cement. No evidence of crystallization was found in ATR-FTIR, except for a small increase in 1340 cm⁻¹ band after 100 °C protocol. Conclusions: Spectroscopic techniques confirmed that PMMA only experienced minor structural changes after induction heating treatments. From a structural viewpoint, these results suggest that electromagnetic induction heating could be a safe disinfection technique for cemented implants in total knee arthroplasty.

Graphical Abstract