Development of a statistical shape model of the human scapula: Development of a statistical shape model of the human scapula for improvement in vehicle safety aspects

Sammanfattning

The human scapula is the fundamental structure of the shoulder and an anatomicallandmark for upper limb movements. Understanding variations in scapula shapecan influence biomechanical modeling, clinical diagnosis, and safety simulation, particularlyin vehicle crash testing. The aim of this study is to develop a StatisticalShape Model (SSM) of the human scapula bone from computed tomography (CT)image data segmentations to analyze and describe the variability in the populationbased on sex, height, age, and BMI.A dataset comprising 70 segmented scapulae derived from an original set of 230segmented scapulae, including healthy samples and samples with Hill-Sachs lesions,some of which are considered unhealthy, was used for this study. The landmarkingset-up consisted of 45 landmarks in total, including 20 anatomical landmarks and25 pseudo-landmarks placed along splines, which provide reliable reference pointsfor shape analysis. Morphing techniques, performed primarily in Python code, wereused to standardize the mesh structures of scapulae by mapping every sample ontoa common average model. For ease of comparison, General Procrustes Analysis(GPA) was used first to remove position, orientation, and scale variance, and thenPrincipal Component Analysis (PCA) to capture the main modes of shape variationin the dataset. Then, a regression model is used on the principal components of thePCA to study variations based on population data.The resulting SSM provides valuable information on the variation of the anatomicalscapula of the population and how demographic factors influence bone shapeand size. The results have potential applications to personalized biomechanicalmodeling, clinical diagnostics, and improved occupant protection in vehicle crashsimulations.