Full‐field strain of regenerated bone tissue in a femoral fracture model

Abstract

The mechanical behaviour of regenerated bone tissue during fracture healing is key in determining its ability to withstand physiological loads. However, the strain distribution in the newly formed tissue and how this influences the way a fracture heals it is still unclear. X-ray Computed Tomography (XCT) has been extensively used to assess the progress of mineralised tissues in regeneration and when combined with in situ mechanics and digital volume correlation (DVC) has been proven a powerful tool to understand the mechanical behaviour and full-field three-dimensional (3D) strain distribution in bone. The purpose of this study is therefore to use in situ XCT mechanics and DVC to investigate the strain distribution and load-bearing capacity in a regenerating fracture in the diaphyseal bone, using a rodent femoral fracture model stabilised by external fixation. Rat femurs with 1 mm and 2 mm osteotomy gaps were tested under in situ XCT stepwise compression in the apparent elastic region. High strain was present in the newly formed bone (ε p1 and ε p3 reaching 29 000 µε and -43 000 µε, respectively), with a wide variation and inhomogeneity of the 3D strain distribution in the regenerating tissues of the fracture gap, which is directly related to the presence of unmineralised tissue observed in histological images. The outcomes of this study will contribute in understanding natural regenerative ability of bone and its mechanical behaviour under loading.

Real-time finite element analysis allows homogenization of tissue scale strains and reduces variance in a mouse defect healing model

“…The mechanical environment during fracture healing is greatly dependant on the geometry of bone, its microstructure, mechanical properties and the degree of mineralisation 9 , 10 . Strains propagate differently through each individual bone, providing a variety of mechanical stimuli throughout the tissue 11 . This geometric variance is seen from traumatic fractures in humans 12 to well controlled osteotomies in sheep 13 or murine models 14 .…”

A predictive model for fracture in human ribs based on in vitro acoustic emission data

“…The prediction of bone fracture under stress is a problem of practical interest. Recently, some medical imaging techniques have been developed to estimate the degree of deformation of a bone based on medical images 1 . This, coupled with computationally adequate constitutive models, provides a potential method for predicting the strength capacity of bone.…”

“…Recently, some medical imaging techniques have been developed to estimate the degree of deformation of a bone based on medical images. 1 This, coupled with computationally adequate constitutive models, provides a potential method for predicting the strength capacity of bone. However, there is still considerable uncertainty about the accuracy of such methods.…”

Reducing variance in a mouse defect healing model: Real-time Finite Element Analysis allows homogenization of tissue scale strains

“…The mechanical environment is greatly dependant on the geometry of bone 9 . Strains propagate differently through each individual bone, providing a variety of mechanical stimuli throughout the tissue 10 . This geometric variance is seen from traumatic fractures in humans 11 to well controlled osteotomies in sheep 12 or murine models 13 .…”