- A new electrochemically graded hydroxyapatite coating for osteosynthetic implants promotes implant osteointegration in a rat model. Schmidmaier, G., Wildemann, B., Schwabe, P., Stange, R., Hoffmann, J., Südkamp, N.P., Haas, N.P., Raschke, M. J. Biomed. Mater. Res. (2002)