Osteoinduction within porous polysulfone implants at extraosseous sites using demineralized allogeneic bone matrix

The objective of this study was to determine if bone induction could occur in implants of porous polysulfone (PPSF) impregnated with particles of demineralized allogeneic bone matrix (DABM). DABM-PPSF composites were fabricated by inserting DABM particles into PPSF specimens. The porous implants were produced by sintering polysulfone particles (850-1180 micron in diameter). DABM particles were prepared by demineralizing rat cortical bone in 0.6N HCl at 4 degrees C for 18-24 h. A composite DABM-PPSF specimen and three "controls" were implanted subcutaneously at abdominal sites in 30 adult Sprague-Dawley rats. The three controls were whole DABM (4 X 4 X 1 mm), particulate DABM (1 X 1 X 1 mm), and porous polysulfone (5 X 5 X 1 mm). Microradiographic and histological evaluation of DABM-PPSF composites revealed chondrogenesis within the pores of the specimens at 10 days, followed by ossification and fatty marrow production at 21 and 43 days. This histological sequence was similar to that seen with DABM controls. The tissue response to porous polysulfone did not prevent the osteoinductive process. These results suggest that an osteoinductive material such as DABM may be useful in augmenting the implantation of porous implants at osseous sites in which the potential for bone regeneration is limited.