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This dissertation, Prediction of Pathological Fracture Risk Due to Metastatic Bone Defect Using Finite Element Method by Wang-to, Derek, Lai, 黎弘道, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled Prediction of Pathological Fracture Risk due to Metastatic Bone Defect using Finite Element Method Submitted by LAI Wang To Derek for the degree of Master of Philosophy at the University of Hong Kong in August 2006 Pathological fractures secondary to metastatic bone defect reduce the patient's quality of life and should be prevented by prophylactic fracture fixation. This must be accompanied by a reliable guideline to decide which patient has the highest fracture risk before treatment is given. Although the existing guidelines are simple to use, the accuracy in fracture risk prediction might be jeopardized as the actual activities resulted in pathological fracture were rarely under consideration. The aim of this study was to predict the pathological fracture risk of a finite element model of femoral shaft with simulated metastatic defect by using the Factor of Risk (Φ), which is a ratio of the applied load to the failure load of any structural element. Fracture is expected if the Factor of Risk is larger than or equal to one. A finite element model of femoral shaft was generated based on the Standardised Femur model. It was then validated by comparing the torsional and bending strength of the femoral shaft model with the in-vitro biomechanical studies of femur in the literature. Simulated metastatic defects of different geometry, orientation, location and size were created on the femoral shaft model to determine the torsional strength, bending strength and strength reduction with respect to the intact femoral shaft model. The Factor of Risk was then calculated by using the torque and bending moment acting on the femur of various daily activities measured with instrumented implant in the literature and the torsional and bending strength of defect models. It was found that with the similar percentage of cross-sectional area removed, there was a larger strength reduction in cortical defect than transcortical defect. The defect located on the medial or lateral cortex resulted in a larger strength reduction in bending than in torsion. Also, the defect size and activity leaded to fracture was consistent with previous clinical study. Lastly, the following defects resulted in femoral fracture during stumbling and should be treated with prophylactic fracture fixation. ƒ Mediolateral transcortical defect larger than 0.4 of the average femur diameter at mid shaft. ƒ Anterior, posterior and lateral cortical defect that remove more than 60% of the cross-sectional area. ƒ Medial cortical defect that remove more than 40% of the cross-sectional area. The Factor of Risk was found to be an effective way to predict the pathological fracture risk and should be validated by prospective study in the future. An abstract of exactly 395 words DOI: 10.5353/th_b3706083 Subjects: Stress fractures (Orthopedics)Femur - Wounds and injuriesFinite element method

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