The “2 to 10% strain rule” for fracture healing has been widely interpreted to mean that interfragmentary strain greater than 10% predisposes a fracture to nonunion. This interpretation focuses on the gap-closing strain (axial micromotion divided by gap size), ignoring the region around the gap where osteogenesis typically initiates. The aim of this study was to measure gap-closing and 3D interfragmentary strains in plated ovine osteotomies and associate local strain conditions with callus mineralization. MicroCT scans of eight female sheep with plated mid-shaft tibial osteotomies were used to create image-based finite element models. Virtual mechanical testing was used to compute postoperative gap-closing and 3D continuum strains representing compression (volumetric strain) and shear deformation (distortional strain). Callus mineralization was measured in zones in and around the osteotomy gap.Aims
Methods
To fully verify the reliability and reproducibility of an experimental method in generating standardized micromotion for the rat femur fracture model. A modularized experimental device has been developed that allows rat models to be used instead of large animal models, with the aim of reducing systematic errors and time and money constraints on grouping. The bench test was used to determine the difference between the measured and set values of the micromotion produced by this device under different simulated loading weights. The displacement of the fixator under different loading conditions was measured by compression tests, which was used to simulate the unexpected micromotion caused by the rat’s ambulation. In vivo preliminary experiments with a small sample size were used to test the feasibility and effectiveness of the whole experimental scheme and surgical scheme.Aims
Methods
The aim of this study was to establish a reliable method for producing 3D reconstruction of sonographic callus. A cohort of ten closed tibial shaft fractures managed with intramedullary nailing underwent ultrasound scanning at two, six, and 12 weeks post-surgery. Ultrasound capture was performed using infrared tracking technology to map each image to a 3D lattice. Using echo intensity, semi-automated mapping was performed to produce an anatomical 3D representation of the fracture site. Two reviewers independently performed 3D reconstructions and kappa coefficient was used to determine agreement. A further validation study was undertaken with ten reviewers to estimate the clinical application of this imaging technique using the intraclass correlation coefficient (ICC).Aims
Methods
