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Title: Preparation of the acetabular socket for implantation of a novel flexible horse-shoe cup
Author: Latif, Ahmed Muhsin Hussein
Awarding Body: St George's, University of London
Current Institution: St George's, University of London
Date of Award: 2011
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Abstract:
The MITCH PCRTM Cup is an evolution of the anatomic, flexible Cambridge Cup. The Cambridge Cup two layer mechanical interlock design has been converted to a mono-block structure, where the bearing articulation is formed of the same material as the bulk of the cup. The cup has an outer surface that should enhance long term bony fixation. The Cambridge Cup metal on polyethylene bearing has been changed to a ceramic on polyetheretherketone bearing. Prior to seeking Ethical Committee approval for the first MITCH PCRTM Cup clinical study, validation that the acetabulum could be prepared in a manner which would allow the MITCH PCRTM Cup to be implanted safely, was undertaken. This study describes the four phases of the validation process and the modification made to the cup design in order to ensure safe acetabular preparation. The first study investigated the effect of interference fit on cup deflection. An interference fit of O.5mm or less was required to ensure polar contact necessary for safe tribological performance. The second study examined the variability of socket dimensions achieved in foam blocks, using reamers provided by five different commercial manufacturers. Excessive socket undersizing was a common finding with all but the EPM reamers. These reamers were validated for accuracy and precision. In the third study, EPM reamers were used to ream cadaveric bone. The socket dimensions obtained were variable with an interference fit of up to 1.8mm obtained. Bony protrusions were observed which could also increase cup deflection and compromise proper cup seating. As a consequence, the cup internal geometry was modified to accommodate the spectrum of findings observed. The fourth study used the modified cups and a new reaming strategy comprising both conventional and custom MITCH PCRTM finishing reamers to achieve safe acetabular preparation. The results showed satisfactory clearance was achieved at the cup side arms in all cases. The reaming solution was appropriate for progression to the first clinical implantation. The surgical technique manual was completed and the cup was CE marked.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (M.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.559386  DOI: Not available
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