Tissue reactions following total hip arthroplasty - a Raman microscopic study on dogs

A quantitative determination of the mineralization of bone tissue and of th e hydroxyapatite (HA) content of HA coatings following total hip arthroplas ties in dogs was performed using an optimised FT Raman microscope (inverted microscope, high throughput of radiation) that allows minimal sample prepa ration without fluorescence. The lateral resolution reached down to 10 mu m . A similar cross-sectional course of the HA content - reaching from the im plant body to the ongrown bone - was found in all cases. In the immediate v icinity of the prosthesis a large HA content could be observed that decreas ed to a minimum towards the periphery of the coating and increased at the s ite of the ongrown bone. For the interface between bone and HA coating a tr ansitional zone was observed at a lateral distance of 30-40 mu m to the imp lant. Bone ingrown into the gap between detached HA coating and implant had a lower HA content than bone ongrown onto the coating peripherally. Thus, Raman microscopy can determine the relative age of bone tissue at different sites in the course of implant integration.