Histological behavior of HDPE scaffolds fabricated by the "Press-and-Baking" method

High density polyethylene (HDPE) scaffolds were fabricated by a new "Press-and-Baking" method without using solvents. This method involved mixing HDPE and salt particles, then pressing and baking to produce porous scaffolds after the salt was leached out. The HDPE scaffolds from 80 wt% salt had strength and flexibility comparable to commercial Medpor HDPE implants. The HDPE scaffolds provided larger and more pores than Medpor. The HDPE scaffolds were oxidized by ozone to investigate the effect of increased hydrophilicity on tissue healing. The HDPE scaffolds fabricated were implanted subcutaneously into rats for 28 days to evaluate the biocompatibility compared with Medpor. The HDPE scaffolds exhibited suitable tolerance with surrounding tissue. Although the tissue ingrowth in the HDPE scaffolds infiltrated the pores slower, denser tissue formation was organized in the scaffolds, while Medpor allowed tissue to infiltrate more readily into the interconnective pores. These results indicate that the difference in porous structural morphology affects tissue ingrowth. In contrast, the increased hydrophilicity by ozone oxidation had little effect on tissue ingrowth.