[Truncated abstract] Renewed interest in the fixation of fractures using plates has been stimulated by an improved understanding of the biology of fracture healing and a drive towards minimally invasive surgery. This has led to a change in the way we use plates nowadays and the way in which we build the bone-plate construct, as well as the development of new implants better suited to these techniques. As a result of this, we have now the potential to safely expand the indications for plate fixation especially in the management of fractures in osteopenic bone. This thesis provides scientific evidence allowing for better formulation of the optimum way to use the modern plating systems in the clinical setting. Biological fracture repair with conventional plates, in terms of a less rigid construct to enhance fracture healing, is becoming increasingly popular. By omitting screws the construct becomes more flexible with a risk of fixation failure. It was the aim of the first paper to investigate in an experimental model the construct strength of different conventional plate lengths and number / position of the screws, and if an oblique screw at the plate end could increase the fixation strength. Our data suggest that the plate length is the most important factor in withstanding forces in cantilever bending. Longer plates with an equal number of screws require greater peak loads to failure than short plates with more screws. Furthermore, an oblique screw at the plate end produces an increased strength of fixation in all different test setups. However, the difference is more significant in shorter plates and in constructs with no screw omission adjacent to the fracture site. ... Following cyclic loading, however, locking plates can better retain fracture reduction compared to compression plates. On the other hand, under torsional load the compression plate appears to be biomechanical superior to the locking system. In supracondylar comminuted femur fractures, combining the two principles results in less plastic deformation, and a higher load to failure compared to their single application. The last two papers examine the behaviour of locking plates in osteopenic bone. In cadaveric intra-articular calcaneal fractures, the locking plate showed a significantly lower irreversible deformation during cyclic loading and a significantly higher load to failure. In dorsal and volar fixed angle distal radius constructs in a cadaveric model, all constructs showed adequate stability with minimal deformation on fatigue testing under physiological conditions in good bone quality. In osteoporotic bone, however, dorsal fixed angle constructs are stiffer and stronger than volar constructs. The addition of a styloid plate to a volar plate does not significantly improve stability.
| Identifer | oai:union.ndltd.org:ADTP/221391 |
| Date | January 2007 |
| Creators | Stoffel, Karl Kilian |
| Publisher | University of Western Australia. School of Surgery and Pathology, University of Western Australia. School of Mechanical Engineering |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Karl Kilian Stoffel, http://www.itpo.uwa.edu.au/UWA-Computer-And-Software-Use-Regulations.html |
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