Surface engineering and coatings for metallic orthopaedic implants: an integrative review of biological performance and clinical translation

Coatings modify metallic orthopaedic implant interfaces, but their clinical value depends on biological safety and function during service. This integrative review examines bone-facing arthroplasty interfaces and internal fracture fixation. It links infection control and bone integration to corrosion, wear and coating integrity across titanium, stainless steel, cobalt–chromium and magnesium substrates. The original corpus comprised supplied bibliographic exports and targeted additions, rather than a comprehensive, reproducible search. After exclusion of two unavailable full texts, the review retained 27 primary reports. The sole author verified animal judgements; laboratory appraisal used descriptive criteria. Independent dual appraisal was not performed. Additional published clinical, retrieval, and mechanistic literature broadens the synthesis beyond the retained appraisal denominator. Experimental studies support biological activity under specific conditions. Randomised trials of antibiotic-loaded hydrogel coatings provide evidence for early infection prevention in defined settings. Conversely, long-term knee comparisons and registry analyses do not demonstrate a general clinical advantage from coating alone. Magnesium requires time-matched assessment of degradation, residual support, and healing. Heterogeneity in composition, implant role, exposure, and outcomes prevents a defensible ranking of coating families. A candidate antimicrobial exposure range must preserve host-cell function and integration on the same finished surface. Its persistence after sterilisation, ageing and mechanical damage requires separate evaluation. The review contributes a framework for assessing concurrent function and device-specific durability. Limited ascertainment and single-reviewer appraisal restrict the conclusions; laboratory activity alone cannot establish clinical benefit.