The cyclic loads influence on mechanical parameters of morselized bone graft

Prosthetic components are subject to wear at the prosthetic-bone interfaces after hip replacement. Over time, this causes the healthy pelvic bone around the implant to deteriorate to the point that revision surgery is required. In this case, the technique of impaction bone grafting (IBG) is used with various osteoplastic materials (OPM). Therefore, the OPM becomes an important mechanical link that takes on cyclic loads during the patient’s physical activity. Predicting long-term stability of the endoprosthesis after revision surgery using IBG is inextricably linked to understanding the mechanical behavior of OPM in the form of morselized bone graft – a mixture of crushed particles human cortical and trabecular bone. The article provides an experimental and numerical study of the elastic and viscoelastic parameters of the bone-plastic material based on morselized bovin bone graft. The experiments were carried out on single-cycle and cyclic constrained compression of the OPM. The problems of compressing the OPM are solved numerically based on the obtained parameters. Instantaneous modulus of elasticity and Poisson's ratio were obtained for single-cycle loading. The values of the instantaneous modulus of elasticity under cyclic loading were obtained for “dry” specimens and containing an aqueous solution of glycerol, simulating wound “blood”. The comparison was made of the compressive stresses during the relaxation process of the OPM, obtained numerically and experimentally. The values of instantaneous elastic moduli increase not only with increasing number of cycles, but also with increasing applied load in the test. The modules of specimens with “blood” are larger than those of “dry” specimens. The obtained parameters make it possible to describe the viscoelastic behavior of osteoplastic materials based on morselized bone allograft using Prony series in finite element programs with numerical modeling.