Abstract:

BACKGROUND: Previous studies mostly have two or more samples for experiments, and the longitudinal stress relaxation experiments are preferred.
OBJECTIVE: To compare the horizontal and vertical tensile stress relaxation of the distal femoral cancellous bone, and to provide the biomechanical parameters of the distal femoral cancellous bone.
METHODS: Ten femur samples from normal male corpses, aged 20-30 years, were selected, 5 for each side. The femoral samples were taken out from the corpses within 1 hour after autopsy. The right femoral samples were covered with saline-soaked gauze, saved in -20 ℃ refrigerator. Before experiment, the samples were taken to be thawed in room temperature and made into specimens of 20 mm×20 mm×20 mm. Firstly, longitudinal stress relaxation experiments were performed in 10 specimens, and 24 hours later, horizontal stress relaxation experiments were performed in these 10 specimens. Strain acceleration was 0.5%/s, experimental time was set to 7 200 s, and 100 experimental data were collected.
RESULTS AND CONCLUSION: The longitudinal and horizontal stress relaxation was 0.58 MPa and 0.72 MPa at 7 200 s, respectively. The stress relaxation curve changed based on the relation of logarithm. The longitudinal creep strain at 7 200 s was lower than the horizontal one. The stress relaxation equation of the distal femur cancellous bone based on the three-parameter model can well reflect the stress relaxation properties of the distal femur cancellous bone.