Validation of canine cancellous and cortical polyurethane foam bone models

The purpose of this study was to develop standard canine cortical and cancellous polyurethane foam (PUF) bone models. Canine cancellous and cortical bone mineral densities were determined with dual-energy- x-ray absorptiometry (DXA). Polyurethane foam was cast in two densities, corresponding to the predetermined canine cancellous and cortical bone mineral densities for use as synthetic bone models. Cancellous bone screws (4.0 mm and 6.5 mm) were extracted from both canine cancellous bone segments and blocks of cancellous density PUF. Cortex bone screws (3.5 mm and 4.5 mm) were extracted from both canine cortical bone segments and blocks of cortical density PUF. There was not any difference in the cancellous screw pull-out forces between cancellous density PUF and canine cancellous bone. Cortex screw pull- out forces were significantly less for cortical density PUF than for canine cortical bone. Cancellous density PUF makes an excellent cancellous bone model for use in implant testing.