Bioactive Surface Coatings for Implants

Abstract

Bioactive surface coatings transform inert implant substrates into biologically instructive interfaces that promote osseointegration, resist bacterial colonisation, or deliver therapeutic agents locally, yet the translation from laboratory coating to clinically approved implant surface remains slow and unpredictable. We evaluated 216 bioactive coating programmes conducted across materials-science and clinical centres in Estonia, Switzerland, and France between 2015 and 2024, spanning five coating categories: hydroxyapatite and calcium phosphate coatings, antimicrobial silver and copper coatings, drug-eluting polymer coatings, bioactive glass coatings, and peptide- and growth-factor-functionalised surfaces. A Bioactive Coating Translational Index (BCTI) was constructed from five sub-scores -- biological efficacy magnitude, coating adhesion durability, controlled release precision, in vivo biocompatibility confirmation, and manufacturing scalability -- with weights from regression against progression to regulatory submission or commercial adoption. BCTI correlated with translational advancement at r = +0.83 and discriminated advancing from stalled programmes with an AUC of 0.878. Hydroxyapatite coatings scored highest (mean BCTI 0.814), while peptide-functionalised surfaces trailed at 0.592. Only 33.8 percent of programmes exceeded the 0.75 BCTI threshold. Biological efficacy magnitude carried the largest regression whttps://stanfordgroup.org/index.php/IABLA/$$$call$$$/grid/users/author/author-grid/add-author?submissionId=539&publicationId=539eight (beta = +0.276), followed by coating adhesion durability (beta = +0.230).