Ta/PEEK cages with enhanced hydrophilicity and cell adhesion improve intervertebral fusion in a rabbit model of extreme lateral intervertebral fusion

This study developed bioactive cages by fabricating hydroxyapatite-coated titanium (HA/Ti) and tantalum-coated PEEK (Ta/PEEK) cages and evaluated their physicochemical properties, cellular responses, and intervertebral fusion performance in a rabbit XLIF model. Both coatings improved surface wettability and maintained the intrinsic mechanical properties of the substrates. Ta/PEEK showed superior coating adhesion and enhanced BMSC adhesion-related marker expression, whereas HA/Ti more strongly promoted osteogenic differentiation and matrix mineralization in vitro. In vivo, both coated cages significantly improved intervertebral fusion compared with uncoated Ti and PEEK cages. HA/Ti induced greater new bone formation, while Ta/PEEK enhanced cell adhesion and angiogenesis, as indicated by increased CDH1, ITGα2, CD31 and HIF-1α expression. These findings suggest that Ta/PEEK cages provide a mechanically compatible and biologically active strategy for improving intervertebral fusion and represent a promising platform for next-generation printed spinal implants.