Silicate-apatite composite layers on external fixation rods and in vitro evaluation using fibroblast and osteoblast

A silicate-apatite layer was formed on commercially available anodically oxidized titanium rods using Na(2)SiO(3)-containing supersaturated calcium phosphate solutions. With the increase in the concentration of Na(2)SiO(3) in the supersaturated calcium phosphate solutions, the amounts of silicon that precipitated on the titanium rods increased from 0 to 0.07 +/- 0.02 microg/cm(2); meanwhile, the amounts of calcium and phosphorus that precipitated on the titanium rods decreased from 11.6 +/- 1.6 and 5.7 +/- 2.0 microg/cm(2) to 2.6 +/- 0.5 and 3.0 +/- 1.0 microg/cm(2), respectively. The present silicate-apatite composite layers, which demonstrated increased fibroblastic proliferation and osteoblastic proliferation and differentiation in vitro, are promising as coating layers on external fixation pins for decreasing the pin tract infection rate in vivo.