Bone ingrowth comparison of irregular titanium and cobalt-chromium coatings in a translational cancellous bone model

The use of cobalt-chromium (CoCr)-bearing surfaces in total joint replacement (TJR) remains the predominate bearing surface. The conundrum with using this biomaterial has been selecting an ideal porous coating to assure reproducible skeletal attachment. There has been evidence that smooth CoCr beads may be inferior for skeletal attachment compared to identically shaped titanium (Ti) beads. Recent in vitro studies have demonstrated that an increased surface area and roughness favors osteoblast adhesion to metallic biomaterials. Therefore, we hypothesized that an irregular shape CoCr bead with an increased surface texture would help correct the negative bone responses that have been reported with smooth beaded CoCr coatings and thus allowing for bone ingrowth equivalently as an irregular commercially pure Ti porous coating with similar porosity. This investigation employed a weight-bearing translational sheep cancellous bone model to accurately simulate a cancellous bone response as it would be clinically in a human TJR. The data analyses obtained from this investigation revealed similar bone responses between the porous coatings. By 12 weeks the irregular shape CoCr coating was able to achieve similar bone ingrowth with skeletal interlock when compared to a clinically proven Ti porous coating.