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Published byDennis Lynch Modified over 9 years ago
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Vidhya sundhararaj 2115580 Supervisor Prof Mark Taylor
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Population based studies are important for implant study, risk assessment for fracture, pre-clinical studies. Modelling of single femur or limited number of femur excludes inter-patient variability and extrapolation to population makes less sensible. Also creating multiple models is time consuming. Statistical modelling overcomes this issue of model generation.
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To statistically model femur that represents maximum variation in femur population in terms of bone geometry, material property and forces and analysing if force can predict geometry and material property.
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1 PCA on Forces 2 PCA on simple geometry 3 PCA on registered geometry 5 PCA with Density 1 Regression on force and simple geometry 2 Regression on force and registered geometry 3 Regression on force and density 4 PCA on surface nodes
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A data reduction method that accounts for most of the variation in the original data. The obtained variables are Called principal components & are uncorrelated to each other.
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Time for stance was obtained from musculoskeletal models in OpenSim. Muscolo skeletal models developed by Saulo martelli
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26 muscle forces On femur and hip joint Forces.
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9 modes 36.1185142482350 49.0151734147590 60.9275970287362 69.0040742900684 75.6375736855110 81.4136554583573 85.3248586585143 89.0679714765587 91.4560197304632
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Surface matching – deforms the baseline surface to match the given target surface. Volume morphing- creates the internal mesh points based on surface nodes.
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6 modes 49.1722858737894 73.5022024924462 82.4879247417899 89.6331203177221 92.5821919508897 95.388699332539 6 modes 46.095523527846 72.063448429335 80.6772566973216 88.1151404184275 92.2940278597457 95.0421274638311
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9 modes 29.5581178678154 48.2866868347216 61.5598539541340 71.8252523911785 80.9403289449587 88.2955863787843 91.9716698668447 93.7112395356659 95.2916843891132
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Analysis was performed on force and shape data to know if shape can predict force. Scatter plots of force and shape
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Regression – a measure of relationship between variable. Has independent variable as predictors and dependent variable as outcome or response variable. Multiple regression analysis – more than one predictor to predict outcome. Stepwise regression – shows significant variables that can predict outcome.
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X1- Head radius X2- neck major radius X3- neck minor radius y- mean peak forces Fx
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Regstat function – performs multiple regression by fitting model to the data. ‘linear‘ - Includes constant and linear terms (default). 'interaction‘-Includes constant, linear, and cross product terms. Mode 1 force represented by shape modes Mode 2 force represented by shape modes
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Interaction model Mode 1 of force Mode 2 of force
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MODE 1 FORCE REPRESENTED BY SHAPE MODES MODE 2 FORCE REPRESENTED BY SHAPE MODES
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TERMS ADDED TERMS REMOVED
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FOR FORCE
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Interpretation of force and shape modes Volume morphing. Density extraction from CT scans and assigning it to meshes. PCA and Regression analysis
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Questions
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