Determining femoral component goodness-of-fit using computer segmentation and numerical simulation

Van Schalkwyk, Etienne P. (2010-03)

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.

Thesis

ENGLISH ABSTRACT: The c2 goodness-of-fit (GOF) test was used to determine which standard femoral component would achieve the best geometrical fit for a specific patient. This was done by creating 3D models from computerized tomography scan data through computer segmentation using Materialise MIMICS. The second step was to measure the morphological dimensions of the distal femur whereof twelve were selected and compared to the dimensions of two commercial femoral prosthesis designs. Thirdly, cadaveric femurs were scanned with a 3D desktop scanner to create a database with the dimensions of healthy knees. The 3D model database of the cadaveric femurs included cartilage layer. A cartilage thickness was added to the CT knee dimensions using a self-organizing map (SOM) calculation based on the healthy knee database. The developed method calculated alignment angles with higher accuracy than presently used and determined preoperatively which size to implant. Kinematic simulations of total knee arthroplasty (TKA) knees were compared to normal knee simulations created in LifeMOD. The articulating surface was the only variable changed between the two simulations and the kinematics of different sizes were evaluated. A method was created to scale the femoral component using the standard available sizes. The completed project will be used as foundation for customization of TKA prostheses.

AFRIKAANSE OPSOMMING: Die c2 graad van passing toets metode was gebruik om te bereken watter standaard femorale komponent ’n patiënt die beste geometries pas. Dit was gedoen deur eerstens 3D modelle gemaak vanaf CT skandeer data deur rekenaar segmentasie met Materialise MIMICS. Daarna was morfologiese dimensies gemeet vanaf die distale femur, waarvan twaalf gekies en vergelyk was teen two kommersiële femorale prostesis ontwerpe. Laastens was kadawer femurs geskandeer met ‘n 3D skandeerder om ’n databasis van gesonde knieë te maak. Die 3D modelle van die kadawer bene het die kraakbeen laag bevat. Die kraakbeen dikte was by die CT knie dimensies gevoeg d.m.v. SOM en die gesonde knie databasis. Die nuwe metode bereken die belynings hoeke met hoër akkuraatheid as wat huidiglik gebruik word en bereken voor die operasie watter grote om te gebruik. Kinematiese simulasies van knie prostesis was vergelyk met ’n normale knie simulasies gemaak in LifeMOD. Die artikulêre oppervlakte was die enigste veranderlike tussen die twee simulasies en kinematika van verskillende grotes was ondersoek. ‘n Metode was geskep om die standaard femorale komponent se skaal te verander vir ’n beter passing.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/4320
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