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STRUCTURAL ANALYSIS DRIVEN SHOULDER ARTHROPLASTY

Abstract

Shoulder arthroplasty, the most common treatment option for patients diagnosed with end-stage glenohumeral osteoarthritis, is able to provide pain relief and restore some functionality. However, this highly advanced surgical procedure often suffers from a major complication of glenoid prosthesis loosening. The problem is magnified during repeat surgeries mainly due to the minimal quantity of bone in the glenoid vault. The goals of this dissertation were to perform structural analysis of normal and osteoarthritic glenoid, evaluate glenoid design variable effects on restoring long-lasting functionality to damaged shoulders, and create a finite element model (FEM)-based simulation process for computing subject-specific internal glenoid bone remodeling.3D computer models of normal and osteoarthritic scapulae were created using high-resolution volumetric computed tomography images. The computer models were used for glenoid structural analyses. The morphological measurements were comparable to prior studies. The glenoid was found to be approximated by geometric analogs. The osteoarthritic scapula was highly retroverted compared to the normal, and had relatively higher glenoid bone density. Internal glenoid morphology was quantified for the first time. Two and three dimensional stress analysis was used to compare glenoid prosthesis design variables. A custom program assigned location-specific material properties to the bone elements, based on the computed tomography data, making the FEMs similar to the actual scapula. Cemented or uncemeneted polyethylene pegs, compared to metal, gave stresses comparable to intact scapula.Two dimensional FEM based simulation process for normal glenoid bone remodeling was successfully created and validated. The "element" approach better predicted the actual specimen bone density distribution than the "node". Some of the findings agreed with past studies that is, obtaining "checkerboard" pattern in the "element" approach. The various combinations of multiple loads had minimal effect on the predicted bone density distribution.The computer modeling, numerical stress analysis, and the simulated bone remodeling allowed successful glenoid structural analysis. The approach adopted improved our understanding of the glenoid prosthesis and successful shoulder arthroplasty

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