Characterization of the mechanical and ultrastructural properties of heat-treated cortical bone for use as a bone substitute

Heat-treated bovine cortical bone has been proposed as an alternative to bo ne grafts and synthetic bone substitutes because it may combine the advanta ges of allografts (high stiffness and strength) and synthetic materials (ab undant supply, reduced risk of rejection and disease transfer). Its mechani cal properties and ultrastructure, however, are not well characterized. To address this, we compared the compressive (n = 20, bovine bone) and tensile (n = 26, bovine bone) mechanical properties and the ultrastructure (n = 12 , human bone) of intact versus 350 degrees C heat-treated cortical bone. Th e 350 degrees C heat-treated bone had a mean +/- SD elastic modulus similar to the intact bone for both compression (16.3 +/- 2.2 GPa, pooled; p = 0.6 8) and tension (16.3 +/- 3.7 Cpa, pooled; p = 0.95). It also maintained 63% of the intact strength in compression but only 9% in tension (p < 0.001). Infrared scans and X-ray diffraction patterns showed no differences between the 350 degrees C heat-treated and intact bone but large differences betwe en ashed (700 degrees C) and intact bone. Similarly, heat-treated bone prev iously has been shown to be biocompatible and osteoconductive. We conclude, therefore, that 350 degrees C heat-treated cortical bone may be an excelle nt load-bearing bone substitute provided that it is loaded in compression o nly in vivo and is shown by future work to have acceptable fatigue properti es. (C) 1999 John Wiley & Sons, Inc.