The effect of gamma irradiation on the mechanical properties of human
bone was examined. Specimens of cancellous bone were cut from the proximal
epiphyseal region of fresh-frozen tibiae and divided into control and
irradiated groups according to anatomical region. The irradiated groups
were exposed to 10,000, 31,000, 51,000, or 60,000 gray (1.0, 3.1, 5.1, or
6.0 megarad). The specimens were tested in compression to failure to
determine failure stress, strain to failure, and elastic modulus. Failure
stress and elastic modulus were found to be proportional to the square of
the density and were normalized with respect to this property. Significant
differences in normalized failure stress (p less than 0.001) and normalized
elastic modulus (p = 0.003), when compared with the values for matched
control specimens, were found only for the specimens that had been
irradiated with 60,000 gray (6.0 megarad).