It is estimated that the UK has more than 19 million people aged over 50, with about 9.4 million aged 65 or more [1]. In 2000, fragility fractures represented an estimated cost of £1.8 billion [2] to the UK. Depending on the severity, treatment can include surgical intervention where plates, screws and wires are used to stabilise the fracture. However, fracture fixations can fail, leading to two or more interventions, increasing costs and trauma to patients. The mechanical test performed on these fixations represented the fracture as flat line or a gap between the fractured bones [3, 4]. Recent research has shown that the geometry of the fracture have an impact in the response of the system, proving that a more close representation of the fracture is still needed in order to correctly assess and test the designs of fracture fixations. The aim of this work was therefore to characterise real bone fractures in terms of its shape and surface properties. Transverse fractures were successfully generated in ten porcine femurs, using a specially designed three-point rig. Post-fracture the specimens were scanned in a µCT machine (XtremeCT, Scanco Medical AG, Brüttisellen, Switzerland) with a resolution of 82 microns. Various metrics were captured from each specimen, including length of fracture and range of feature sizes. Mechanical testing was performed of the fractured bones under axial load and rotational displacement. The torsional results were compared with the results obtained from the computational simulations, for each specimen and agreement was observed. The experimental results showed that the torsional behaviour for transverse fractures reached a plateau after 5 degrees of rotational displacement, and the average rotational stiffness was found to be 1.64 ±0.77 Nm/degree. Torsional behaviour in the FE models was particularly sensitive to changes in the elastic modulus of the specimen, coefficient of friction between the bone and the geometry of the fracture. Future work is still needed. An investigation of the effects of the microdamage caused by the mechanical test can be useful and the inclusion of locking plates in the models could be interesting.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:640627 |
| Date | January 2014 |
| Creators | Zapata Cornelio, Fernando Yitzhak |
| Publisher | University of Leeds |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.whiterose.ac.uk/8705/ |
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