This is an interdisciplinary research project in which the methods of biomechanical and design engineering are focused upon a problem in orthopaedics. The anterior cruciate ligament (ACL) is the major ligament in the knee and is often torn during athletic competition as well as every day activity. The ACL is made up of two functional bundles, which help to stabilize the knee. Until recently, ACL reconstruction only replaced one of these bundles; however, research shows that both bundles should be replaced to more fully restore normal knee functionality. The aim of the research was, therefore, to evaluate the mechanical aspects of the double-tunnel-double-bundle ACL reconstruction technique. The research was directed towards designing a new and improved surgical device to improve ACL reconstruction: The current study used a computational model and experimental testing to explore the mechanical parameters of the tendon graft and knee bones to investigate the effects of double tunnel drilling in tibia and femur during ACL reconstruction. The thesis presents the findings of research into three aspects of double-tunnel-double-bundle ACL reconstruction. The first aspect of the study involves clinical and computational analysis of a single-tunnel-singlebundle (SB) ACL reconstructed knee with a double-tunnel-double-bundle (DB) ACL reconstructed example. The study tried to show the advantage of the DB technique over the conventional SB technique. The anatomical geometries of both SB and DB examples were used to create a finite element model and investigate the relative merits of single and double tunnelling, the variations of graft pretension, and tunnel placement on bone stress. The experimental and computational results of both methods were compared and discussed. The second study investigated whether tripling a tendon when using suspensory fixation provides inferior graft strength and a greater cyclical elongation than a doubled tendon graft with suspensory fixation. The tensile stress was found to be lower in the third strand than in the doubled portion. The study was focussed on the mechanical assessment of two different methods of tripling tendons when using suspensory fixation. The third aspect of the study focussed on the design of a new device for fixation of the femoral tripled tendon graft in DB ACL reconstruction technique. The study describes a series of designs and prototypes that were iteratively developed and experimentally tested, leading to a novel tripled tendon graft device. The function of the new device was compared with the conventional methods and tested with a number of animal tendons and bones. The new device with a tripled tendon graft resulted in higher pull-out strength and less graft elongation than that seen using a conventional tripling method.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:558606 |
| Date | January 2011 |
| Creators | Chizari, Mahmoud |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=167333 |
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