Determining femoral component goodness-of-fit using computer segmentation and numerical simulation
Date
2010-03
Authors
Van Schalkwyk, Etienne P.
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
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.
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.
Description
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.
Keywords
Knee, Mimics, gGodness-of-fit, Arthroplasty, Dissertations -- Mechanical engineering, Theses -- Mechanical engineering, Knee prostheses