In vivo and in vitro evaluation of vitreous coatings on cobalt base alloys for prosthetic devices

This work describes the electrochemical and biological response of wires of CrCoMo surgical alloys (F75) covered by two layers of SiO2 coating prepared by sol–gel to evaluate their properties in simulated body fluids and implanted in Lew rats for the in vivo evaluation. Wires were coated by a single layer of hybrid silica (that means that the coating contains Si–CH3 groups) covered by another similar layer containing a suspension of bioactive glass-ceramic particles in the system CaO–SiO2–P2O5 to provide fixation to bone. Standard electrochemical tests were conducted for the in vitro measurements and showed smaller current density for the covered samples than for the uncovered ones after 30 days of immersion. For the in vivo tests the coated wires were inserted in the tibia cortical bone by a press fit technique in Lew rats and analysed after 53 days of being implanted. We observed that none of the wires created an inflammatory response. Moreover the covered wires developed neo formed bone in the surroundings of the samples made of collagen with a vascular development. Uncovered wires did not develop new histionic structure.