Strontium-substituted Nanohydroxyapatite Coatings to Decrease Aseptic Loosening of Femoral Prosthesis: Safety and Efficacy in a Rat Model.

This study aimed to evaluate the safety and efficacy of strontium-substituted nanohydroxyapatite (Sr-nHA) coatings in decreasing aseptic loosening of the femoral prosthetic stem after hip replacement surgery in a rat model. Sr-nHAs (atomic ratio of Sr/(Ca + Sr) of 0%, 5%, 10% and 20%) were prepared by homogeneous phase coprecipitation. Plasma spraying was employed to prepare the Sr-nHA coatings on titanium rod substrate. After microstructure analyses, we investigated the safety and efficacy of Sr-nHA coatings both in vitro and in vivo. Cytotoxicity, histocompatibility, general toxicity, mineralization and osteogenic differentiation tests demonstrated that the Sr-nHA coatings had good safety and efficacy in vitro. Histological observation, fluorescence microscopy, microcomputed tomography, biomechanical test and energy dispersive of X-ray analysis revealed that the Sr-nHA coatings were safe and effective in vivo. In both in vitro and in vivo experiments, the efficacy of the Sr-nHA coatings revealed a dose-dependent effect and the 20% Sr-nHA coating was more effective than the other three coatings. Employing Sr-nHA coatings on titanium implants for surface modification showed safety and great application potential in decreasing the aseptic loosening of femoral prostheses after hip replacement. This kind of coating provides a method for decreasing aseptic loosening of femoral prostheses.