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Bliven, Emily

University of British Columbia

Fall-related hip fractures are common yet devastating injuries with poor outcomes. Conventional prevention approaches may not be effective or fast-acting enough to prevent imminent hip fracture in high-risk individuals; however, the surgical insertion of a prophylactic implant to augment the proximal femur has been demonstrated as clinically feasible. In this thesis I investigate the less-explored aspects of femoral augmentation with a prophylactic implant in a sideways fall from standing, the most common scenario for geriatric hip fracture. Our work encompasses four contributions, the first of which involves developing a method to visualize phenomena occurring at the bone level during a fall impact. We integrated a bilateral high-speed x-ray system into a pre-existing fall simulator and applied it to experiments of seven augmented pelvis-femur specimens. We demonstrated sufficient capture of fracture incidence, kinematic data, and newly documented fracture mechanics in the pelvis in a fall. Second, we evaluated the efficacy and safety of prophylactic intramedullary nailing for hip fracture prevention by building finite element models (FEMs) of six ex vivo specimens in their native state to predict fracture outcome in a fall, and comparing their native fracture severity to experimental outcomes post-augmentation. Prophylactic nailing was not associated with any adverse events or hip fractures, but two pelvis fracture cases were found after fall experiments. Third, we quantified the accuracy of augmented versions of the FEMs in predicting outcomes related to force, pelvis deformations, and fracture. Our validation revealed an acceptable level of accuracy for these models and identified areas for future methodological improvements. Finally, we conducted an FEM study to identify key design features of prophylactic implants for increasing predicted femur force. We found that various implant designs regarding size or stiffness may pose different benefits for different high-risk candidates based on bone density. This work presents a methodology for the evaluation and development of new prophylactic implants for preventing hip fracture in a fall, and provides new insights into the biomechanical response of the femur and pelvis on impact after augmentation. Our results may contribute to the successful clinical use of these devices as an option for hip fracture prevention.

Text

2024-07-11

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/88621

Biomedical Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/