Thesis (Ph.D.)--University of Western Australia, 2007.

Thesis (M.D.S.)--University of Hong Kong, 2003. / Also available in print.

D.Ing. / This thesis studies the application of newer generation engineering materials, specifically carbon fibre reinforced polymers, as bone plates in cases of fractured bones. The application of bone plates subsequent to bone fracture is a very old orthopaedic technique that has always rendered some problems. The rigidity of the bone plate, and thus the plated system as a whole, is of advantage during the healing phase, but of disadvantage later. Bone remodels itself to most efficiently perform the load bearing required of it. In a plated system, the load is born primarily by the plate and therefore protects the underlying bone, leading to osteoporosis and eventual atrophy. All bone plates are made of a material that is totally foreign to the body, and in most cases these are removed after some healing of the bone had occurred. The majority of current research programmes with respect to bone plates are directed towards biodegradable bone plates that reduces in mechanical strength at approximately the same rate as bone gains in its ability to sustain loads. The principle of stimulating bone growth in cases of delayed union and non-union has been studied since the early 1960's. The studies revealed that bone healing can in fact be enhanced by the introduction of a very small electric current to the fracture site. Variations to the mechanisms and position of application of the current, alternating or direct, are well documented. Although the physiological healing process associated with electrical stimulus remains largely unknown, the principle is well established. The phenomenon of galvanic corrosion has been known since the tum of the century. Where two dissimilar materials are in the presence of a conducting media, the more "reactive" of the two materials will react as an anode or electron donor to the other material. An electric current thus will flow from the one material to the other. Having three existing and known phenomena, namely bone plating, bone healing stimulation and galvanic corrosion raises the question of whether these can be combined to yield a solution superior to any current plating mechanism - a plate that would render sufficient mechanical support but act as an electron source and thus as a bone healing stimulus. The purpose of this study is to assess the biological criteria determining the choice of bone plates (inclusive of mechanical, physiological and electrical criteria) and thereafter selecting a material suitable for this dynamic requirement.

Thesis (MMed)--Stellenbosch University, 2014. / No abstract available

published_or_final_version / Dentistry / Master / Master of Dental Surgery

No description available.

No description available.

[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.