Hydroxyapatite/polymer composite flame-sprayed coatings for orthopedic applications.

The complex biological and mechanical requirements for implant materials in the human body generally cannot be furnished by one single material. In the present study, hydroxyapatite/polymer composite coatings with different contents of hydroxyapatite were produced using a flame spray system. This processing route is intended to obtain a coating with an optimal combination of biological and mechanical properties of these two materials for skeletal implants. The composite coatings were produced from a mechanical blend of hydroxyapatite and ethylene methacrylic acid copolymer powders, which were delivered from a fluidized bed powder feeder. Characterization of the coating surface morphology, polished coating cross-sections, and fracture surface morphology was conducted by scanning electron microscopy. The dissolution behavior of the coatings was evaluated with a calcium-specific ion meter. The stress-strain behavior was investigated by tensile testing. The biological and mechanical properties were found to be related to the volume and distribution of the hydroxyapatite in the polymer matrix. This technique provides a means of preparing hydroxyapatite/polymer coatings for application as implants.