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Mandibular reconstruction : biomechanical strength analysis (FEM) based on a retrospective clinical analysis of selected patients

Jędrusik-Pawłowska M., Kromka-Szydek M., Katra M., Niedzielska I.

Acta of Bioengineering and Biomechanics

2013

Vol. 15, no. 2

23--31

Restoration of mandible discontinuity defects continues as a challenge for maxillofacial surgeons. Despite the development of algorithms for reconstruction plates fixation and autogenous grafting techniques, complications are still encountered including screw loosening, bone resorption or delayed/incomplete union. The aim of the study was to analyze the possibility of obtaining bone union in the aspect of biomechanical conditions of two mandible reconstructions using an autogenous iliac crest bone graft stabilized with a reconstruction plate, and to attempt to predict patient outcomes based on strength parameters obtained by the finite element analysis. The authors of the present paper were trying to determine to what extent the reconstruction model and changes occurring in hard tissues of the bone and autogenous graft (simulated by changes in material properties) might help predict individual patient courses. The effort of reconstruction plates was defined using the values of the von Mises stress (σHMH) while the effort of bones was determined based on the values of strain intensity εint. The results of the above mentioned simulations are presented in the form of bar graphs and strain/stress distribution maps. Our strength analyses indicate that uncomplicated healing of grafts fixed with reconstruction plates requires that the initial loading of the stomatognatic system should not result in strain intensity exceeding 20–40 [×10–4]. This range of strain intensity evokes an increase in the mineral phase. The state of nonunion between the mandibular bone and the graft might result from prolonged periods of insufficient loading of the mandible during treatment.

Ocena stabilności zamocowania sztucznej panewki stawu biodrowego

Płomiński J., Watral Z., Michalski A., Sienkiewicz J.

Diagnostyka

2006

nr 3(39)

245-252

W referacie przedstawiono problematykę stabilności zamocowania panewki sztucznego stawu biodrowego po zabiegu rewizyjnym. Wykonano badania eksperymentalne na modelach cielęcego stawu biodrowego z zacementowaną na warstwie ubitych przeszczepów kostnych panewką polietylenową. Po zacementowaniu panewki obciążano ją siłą 1kN przez 100000 cykli a następnie sprawdzano jej stabilność przykładając na jej krawędź siłę ścinającą. Badano wpływ grubości warstwy przeszczepów oraz kierunku działania siły obciążającej na stabilność panewki.

The paper deals with the problem of stability of artificial acetabulum after revision hip arthroplasty. Experimental tests on calf joint with artificial acetabulum cemented into it were performed. Cemented acetabulum was subjected to a cyclic load of 1 kN through 100000 cycles and then the fixing stability was verified by applying a shearing force to its edge. The influence of thickness of bone grafts layer and the direction of loading force on the overall stability was investigated.