Peri- and intra-implant bone response to microporous Ti coatings with surface modification

Abstract

Bone growth on and into implants exhibiting substantial surface porosity is a promising strategy in order to improve the long-term stable fixation of bone implants. However, the reliability in clinical applications remains a point of discussion. Most attention has been dedicated to the role of macroporosity, leading to the general consensus of a minimal pore size of 50-100 μm in order to allow bone ingrowth. In this in vivo study, we assessed the feasibility of early bone ingrowth into a predominantly microporous Ti coating with an average thickness of 150 μm and the hypothesis of improving the bone response through surface modification of the porous coating. Implants were placed in the cortical bone of rabbit tibiae for periods of 2 and 4 weeks and evaluated histologically and histomorphometrically using light microscopy and scanning electron microscopy. Bone with osteocytes encased in the mineralized matrix was found throughout the porous Ti coating up to the coating/substrate interface, highlighting that osseointegration of microporosities (<10 μm) was achievable. The bone trabeculae interweaved with the pore struts, establishing a large contact area which might enable an improved load transfer and stronger implant/bone interface. Furthermore, there was a clear interconnection with the surrounding cortical bone, suggesting that mechanical interlocking of the coating in the host bone in the long term is possible. When surface modifications inside the porous structure further reduced the interconnective pore size to the submicrometer level, bone ingrowth was impaired. On the other hand, application of a sol-gel-derived bioactive glass-ceramic coating without altering the pore characteristics was found to significantly improve bone regeneration around the coating, while still supporting bone ingrowth.

Evaluation of topographical and chemical modified TiAl6V4 implant surfaces in a weight‐bearing intramedullary femur model in rabbit

“…The remodeling process was accompanied by the appearance of osteoclasts. A higher number of osteoclasts at the implant interface at 3 and 6 weeks and a clear reduction of osteoclasts at 12 weeks after implantation was also found in other studies (Braem et al, 2014;Reigstad et al, 2007). In the present work, a higher number of osteoclasts was observed at the implant interface in case of the CaP coated samples (Figure 7) that could also have had a stimulatory effect on bone remodeling via the intimate crosstalk between osteoclasts and osteoblasts (Kular, Tickner, Chim, & Xu, 2012 (Reigstad et al, 2007).…”

Osseointegration Enhancement by Zr doping of Co-Cr-Mo Implants Fabricated by Electron Beam Melting

“…This particular surface texture, EBM-produced cp-Ti and Ti-alloy scaffolds, has also been shown to promote cell attachment, proliferation and differentiation [9,27]. Previous studies with porous titanium have shown that surface irregularities with similar dimensions permit bone ingrowth [28,29]. This was also observed for the present surface texture creating firm mechanical interlocking, resulting in shear forces combined with other forces acting at the interface [30,31].…”

Novel anti-infective implant substrates: Controlled release of antibiofilm compounds from mesoporous silica-containing macroporous titanium

“…Nevertheless, the pore structure is fully interconnected as the open porosity equals the total porosity. The pore window size distribution is relatively small around 1-2 m, but is still relevant for implant applications as we have recently shown that bone ingrowth for pore window sizes between 1 and 10 m is still possible [48].…”