| Summary: | 碩士 === 國立陽明大學 === 復健科技輔具研究所 === 95 === Surgery is a major choice for intertrochanteric hip fracture. As a golden standard, stable fractures should be treated with sliding hip screw system, and it had bee followed for decades. Traditional sliding hip screw systems used in operation with a long four-holed side plate but sliding hip screw systems with two holed side plate had been applied clinically with good results since several years ago. In this study we simulated simple trochanteric fracture model using two, three and four holed DHS systems under one reference load (stance phase of the gait cycle). Several different situations were analyzed by finite elements, and we would discuss the difference at stability and stress distribution in these different DHS systems.
The left femur from a 70-year-old man donor was scanned by computer tomography (CT) to and this imagines were catch by 3D geometry and associated finite element mesh with the CAD package Ansys. Behavior of bone was approximated by an isotropic linear elastic material. Cortical and cancellous bone were distinguished. Only one loading condition was considered. The femur was restrained at distal end of femur model. This study used an appropriately sized two, thee and four holed DHS. Interface between the bone and the implant was considered to be bonded. Fractures were modeled with contact pairs. Distance between fracture fragment micro-motion in each sliding hip screw system was evaluated. von Mises stress distribution at femur and implant were checked, too.
Results showed that sling hip screw systems with two holed side plate had most mobilization and system with four holed side plate had most effect of stress shielding. Stress along implant was concentrated at junction of lag screw and barrel. The most distal screw at all system expressed more stress distribution than other screws. Stress distribution on at femur and micro-motion at fracture site revealed treating with two holed sliding hip system is save in simple type intertrochanter fracture.
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