Miniplatten aus Titan zur Fixation von Gelenkfortsatzfrakturen des Unterkiefers: Evaluation des biomechanischen Verhaltens mittels der Finite-Elemente-Analyse

Liokatis, Paris Georgios (2023): Miniplatten aus Titan zur Fixation von Gelenkfortsatzfrakturen des Unterkiefers: Evaluation des biomechanischen Verhaltens mittels der Finite-Elemente-Analyse. Dissertation, LMU München: Medizinische Fakultät

Abstract

The current publications aimed first to determine which plating technique provides the most rigid fixation and the best biomechanical behavior and second, to examine how the positioning of the lambda plate affects the rigidity of fixation. To assess the rigidity of the osteosynthesis, the displacements of the condylar fragments were measured. The von Mises stresses in the osteosynthesis material were calculated to predict possible material failure in the plates and screws. In addition, the maximum principal strain in the bone was used to indicate potential bone areas that might be susceptible to bone resorption. All four plate designs (alpha, kappa, rhomboid, and trapezoidal) were tested under the same conditions: a load of 500 N simulating the maximum masticatory force of a healthy adult and a load of 135 N corresponding to the reduced masticatory force within the six postoperative weeks. According to our findings, all four plates showed adequate fixation of neck fractures at a load of 135 N with a risk for delayed screw loosening only when the trapezoidal and rhomboid plates were used. On the other hand, the plates showed significant differences when a load of 500 N was applied. Larger plates requiring more screws for fixation, such as the alpha and kappa plates, performed better than the rhomboid and trapezoidal plates, which have half the volume of the former. The alpha and kappa plates showed higher rigidity and better stress distribution in the bone. The trapezoidal plate resulted in less rigid fixation because the micromovements could lead to pseudoarthrosis. The above results may differ if the course of the fracture line or the position of the plate changes. These parameters were examined in the current study for the relatively new lambda plate, for which there is insufficient data to make any conclusions about its application. The rigidity of osteosynthesis using the lambda plate was studied for a load of 500N. According to the results of the present study, the lambda plate provided adequate rigidity only for neck fractures. In contrast, the stability of osteosynthesis was unsatisfactory for basal fractures. Furthermore, in condylar neck fractures, a more cranial placement of the plate should be pursued. Finally, if the Lambda plate is used for basal fractures, it should be combined with an additional plate under the sigmoid notch. The finite element analysis is a computational method, and results apply only to fracture patterns and osteosynthesis materials simulated with current models. The results should be validated by experimental or clinical studies.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Keywords: Finite element analysis, condylar fracture, lambda plate, osteosynthesis, biomechanic
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften ; 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• Fakultäten: Medizinische Fakultät
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 8. März 2023
• 1. Bericht­erstatter:in: Smolka, Wenko