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Non-invasive extending prosthesis

Meswania, Jayantilal Mohanlal; (2006) Non-invasive extending prosthesis. Doctoral thesis , (UCL) University College London. Green open access

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Most sarcomas of the bone occur in patients of a relatively young age including skeletally immature patients. Approximately 50 child sarcomas are treated with limb salvage surgery per year in the United Kingdom. These children need an extendible implant that can be lengthened periodically to keep pace with the growth in the opposite limb. Surgically, invasive devices have been used for the past thirty years with intrinsic problems of infection and long-term recurrent trauma to the patient. To eliminate problems associated with the invasive device I have attempted to develop a non invasive extendible prosthesis by utilising a magnetically coupled drive. The aims of this study were to ascertain the clinical requirements of an electro-mechanical design, evaluate the performance of the proposed design, validate the design by in vitro tests and conclude its effectiveness by conducting an in vivo clinical trial. The final aim was to develop a similar concept for the distraction of juvenile spinal scoliosis. The drive technology used in this device is an induction motor with a gear driven telescoping prosthesis. In very young patients the potential loss of growth in the resected bone usually exceeds the amount of extension that could be built into the prosthesis. Therefore, maximisation of the growth potential was the prime objective of the prospective design. A previously designed two-stage epicyclic gearbox was tested and improvements were made to provide a load carrying capacity identified by in vivo measurements conducted in over 30 patients. In this design the motor configuration is in two parts: a rotor which fits inside the prosthesis and a stator which is an external device used to extend the prosthesis remotely. A compact external drive was developed with focused magnetic flux which required no cooling and operated on a single-phase power supply. The effect of the magnetic rotor on the diagnostic imaging was tested and the findings are reported in this thesis. A number of patients were treated with this new device and the clinical outcome is presented. A different version of the device for use with a spinal rod system was developed for the treatment of juvenile scoliosis.

Type: Thesis (Doctoral)
Title: Non-invasive extending prosthesis
Identifier: PQ ETD:594506
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest. Third party copyright material has been removed from the ethesis. Images identifying individuals have been redacted or partially redacted to protect their identity.
UCL classification: UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Surgery and Interventional Sci > Department of Ortho and MSK Science
URI: https://discovery.ucl.ac.uk/id/eprint/1446454
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