Osseointegration of functionally-graded Ti6Al4V porous implants: Histology of the pore network

Abstract

The additive manufacturing of titanium into porous geometries offers a means to generate low-stiffness endosseous implants with a greater surface area to improve osseointegration. In order to optimize pore size in the scaffolds, it is important to first understand the timeline of osseointegration in pre-clinical models. In this work, selective laser melting was used to produce gyroid-based scaffolds with a uniform pore size of 300 m or functionally-graded pore size from 600 m to 300 m before implantation in New Zealand white rabbit tibiae for 4 and 12 weeks. Initial in vitro assessment with Saos-2 cells showed favourable cell proliferation at pore sizes of 300 and 600 m. At four weeks, histological observations indicated some residual inflammation alongside neovessel infiltration into the scaffold interior and some early apposition of mineralized bone tissue. At twelve weeks, both scaffolds were filled with a mixture of adipocyte-rich marrow, micro-capillaries, and mineralized bone tissue. X-ray microcomputed tomography showed a higher bone volume fraction (BV/TV) and percentage of bone-implant contact (BIC) in the implants with 300 m pores than in the functionally-graded specimens, indicating that these smaller pore sizes may be favourable for osseointegration in leporine bone. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=77 SRC="FIGDIR/small/521963v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@2e319aorg.highwire.dtl.DTLVardef@baa9deorg.highwire.dtl.DTLVardef@e66075org.highwire.dtl.DTLVardef@c6c8c4_HPS_FORMAT_FIGEXP M_FIG C_FIG