| Summary: | 碩士 === 國立陽明大學 === 生物醫學工程學系 === 105 === Abtract
The mandibular condylar fracture is one of common mandibular fractures in mandibular surgeries. Due to the intracapsular fracture in all types of condylar fractures not easy to reduce and fix, condylar fractures are treated conservatively. Thus, the study will focus on exploring the above problem. For condylar restoration is required to open the surgical space and reposition the fracture bone at the same time. This will causes difficulties that surgeons restore the fracture bone in present. For fracture fixation, mini plate is a common clinical way; however, this will cause external soft tissue destruction. To solve this, some studies have proposed the use of headless compression screws fixation. But this is not the dedicated screws which are for the condylar head causing other postoperative complications. In order to solve the above problem, this study will develop the instrument for the surgery and design the headless compression screws for condylar head fractures, and then we’ll discuss biomechanics of the mini plate fixation to solve the aforesaid problems. First of all, the study will collect the clinical problems from surgeons, patents and regulations. Then, using the reconstruction model of the mandible and cranial bone to design and develop the screw and instrument. After rapid prototyping, testing the prototype if is practically feasible to turn the instrument and screws into metal. Once it has been casting, the screws should be tested by the compression force test as well as the convergence and verification of the analysis model to confirm the credibility and numerical accuracy of the model. The pressure values(60.4N) are analyzed by computer simulation, and comparing mini plate fixation and headless compression screw fixation with four kinds of loading conditions(100N、12.8N、76.6N、45 degree angle lateral force). Finally, these prototypes will be put into functional test practically.
The instrument and screw developed in this study can solve the difficulties of the condylar fracture restoration during the surgery. The result shows that the stress didn’t exceed the material breaking strength (933.2Mpa / 480Mpa) and bone strain can be less than 4000μ which didn’t cause bone loss .in addition, interfragmentary motion can less than 150μm
So condylar fractures can have the best healing effect for a patient in the case of liquid diet and using headless compression screws for fracture fixation.
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