<i>AIMS:</i> The primary aim of this thesis was to determine what effect modular intramedullary stems of differing lengths have on the initial stability experienced by the tidial tray and the strain magnitude experienced within the proximal tibia due to the differing modular stems in a primary and revision TKA. <i>NULL HYPOTHESIS: </i>Increasing the length of the implant stem has no affect on the micromotion of the tibial tray relative to the bone surface. Adding a modular stem does not affect the strain distribution within the proximal tibia. <i>CONCLUSIONS:</i> A 40mm or 80mm press-fit modular stem does not enhance initial fixation with hybrid or cementless implantation in either primary or T2A revision TKA. The addition of a modular stem when implanting an uncemented tibial tray may well increase the instability of the construct. Cemented implants with no modular stem have better initial fixation compared to all uncemented implants tested. In a primary and revision T2A TKA scenario the addition of a press-fit or fully cemented 80mm modular stem offers no added translational or rotational stability. In the bone impaction grafting group a fully cemented tibial tray with an 80mm modular stem significantly increased the migrational and inducible displacement stability. The use of cemented modular stems in primary TKA and simple revision TKA reduces the strains experienced in the proximal tibia and causes excessive strains within the distal cancellous bone at the stem tip. Press-fit stems do not cause significant stress shielding but do cause localised areas of high strain at the stem tip, (which may be linked to patient pain and discomfort). A cemented long modular stem provided the best strain distribution within the proximal graft in the T1 models.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:657037 |
| Date | January 2007 |
| Creators | McLean, Alastair J. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/15352 |
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