Constitutive models for constrained compression of unimpacted and impacted human morselized bone grafts

Morselized corticocancellous bone (MCB) is widely used in revision surgery with and without impaction. In the current study material parameters for the nonlinear viscoelastic and plastic responses of impacted and unimpacted human MCBs were determined during constrained compression. These models may be useful in finite element analyses of surgical constructs involving impacted and unimpacted MCBs. MCB is impacted layer by layer in the femoral canal during revision surgery. The influence of different layers on the mechanical properties was therefore also examined by comparing the relaxation strength and elastic and plastic strains for bone pellets impacted in one and two layers during constrained compression of human MCB. The relaxation strength was found to increase significantly by 14% for two layer pellets compared to one layer pellets, and the plastic strains decreased significantly by 15%, while the elastic strains were similar.