Creep characteristics of cancellous bone at 45°between normal and necrotic femoral head / 中国组织工程研究

ABSTRACT

BACKGROUND:The creep characteristics of cancellous bone from necrotic femoral head are important for clinical artificial joint replacement.Therefore,it is necessary to study mechanical properties of cancellous bone at 45°direction.OBJECTIVE:To compare creep properties of normal femoral head and necrotic femoral head at 45°direction based on three-parameter model established creep equation METHODS:A total Of 8 normal and 8 necrotic femoral heads were used.The cancellous bone was harvested at 45° and subjected to creep test on electronic universal testing machine.With simulated temperature field of human body temperature at36.5℃.stress was imposed on the samples by an increase of 5%/s for 7 200 seconds.100 experimental data were collected,and stress relaxation equation was calculated using three-parameter model.RESULTS AND CONCLUSION:The creep curve of the femoral head of normal and necrotic changes was exponential relation.Changes were fast in the first 600 seconds,and strain increased slowly with time,finally entered into balance stage.7 200 s creep of cancellous,bone from necrotic femoral head was less than normal femoral head cancellous bone.Three-parameter model calculation is simple and can well fit the creep of changes in the femoral head.The establishment of such idealized equation quantitatively shows poor visco-elasticity of the necrotic femoral head.