Human primary osteoblast behaviour on microrough zirconia-toughened alumina and on selectively etched microrough zirconia-toughened alumina

Hip arthroplasty cementless acetabular components require excellent mechanical properties, biocompatibility, low friction and good osseointegration with surrounding bone tissue. Zirconia-toughened alumina (ZTA) fulfils these demands but requires combination with a rough metal shell for adequate osseointegration. Surface modifications of ZTA could allow a metal-free solution, thus preserving the bone stock for an eventual revision surgery. In this study, selective chemical etching proved to be an innovative method for the introduction of nano-features on micro-rough surfaces obtained by injection moulding. Results suggest that micro-roughness, fluorine enrichment and nano-porosity at the surface of ZTA play a synergistic role on human osteoblast (hOb) maturation. Among the tested groups, hydrofluoric acid etched “medium” roughness (Sa = 330 nm) ZTA showed the highest and/or earliest ALP expression at both the protein and gene level, while microroughness alone induced only minor effects on hOb maturation on ZTA.