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A finite element model of a complete vertebra was formulated from a previously developed bilaterally symmetric model. This model was verified by comparing its results to those of the previous model and by ensuring that the output was bilaterally symmetric. The applied nodal loads were checked against experimentally measured pressures on the vertebral endplate. Simulations of complete and partial laminectomies on one side of a vertebra were performed. High tensile stresses occurred in the pedicle and in the region of the pars interarticularis as a result of surgery, particularly when the superior half of the lamina was removed.

Fracture of the fibrous networks of normal and irradiated rat dermis have been studied using the SEM. The implications of these observations are discussed with regard to the mechanical behaviour of the tissue in the living animal. It is shown that after radiation the normal fibrous structure of collagen is replaced by a solid mat which is ill adapted to support stress, so that rupture at low stress levels is inevitable.