This study showed that syndesmosis fixation at the level of 30-40 mm above the tibiotalar joint has advantages with regard to stress in screws in comparison with the other evaluated levels.

BackgroundThe purpose of the present study was to compare the results of various types of anchor applications with or without augmentation in both osteopenic and severely osteoporotic bone models.MethodsTwo different types of suture anchors were tested in severely osteoporotic (SOP) and osteopenic polyurethane (PU) foam blocks using an established protocol. An Instron machine applied static loading parallel to the axis of insertion until failure, and the mean anchor failure strengths were calculated. The mode of failure (anchor pullout, suture tear) was recorded. The anchors tested included the Corkscrew® (CS) (Arthrex Inc., Naples, FL, USA) (without augmentation, polymethylmethacrylate (PMMA)-augmented, and bioabsorbable tricalcium phosphate (TCP) cement-augmented) and Corkscrew® FT II (CS FT II) 5.5 mm (without augmentation as used routinely).ResultsThe mean failure loads for both SOP and osteopenic PU foam blocks, respectively, were as follows: CS, 16.2 and 212.4 N; CS with TCP, 75.2 and 396 N; CS with PMMA, 101.2 and 528.8 N; CS FT II, 13.8 and 339.8 N.ConclusionsAugmentation of CS with TCP or PMMA would be essential to SOP bones. In the osteopenic bone model, although anchor fixation augmented with PMMA is the best fixation method, CS augmented with TCP cement or CS FT II without any need for augmentation may also be used as an alternative.

Stress that occurs in syndesmotic screws is closely related to their geometry and dimensions. According to the results, a 3.5-mm cortical screw with the ideal screw design regarding optimal parameters to resist against stresses in the syndesmosis seems more reasonable to choose in syndesmotic fixation.

Background:Proximal femoral fracture rates are increasing due to osteoporosis and traffic accidents. Proximal femoral nails are routinely used in the treatment of these fractures in the proximal femur.Aims:To compare various combinations and to determine the ideal proximal lag screw position in pertrochanteric fractures (Arbeitsgemeinschaft für Osteosynthesefragen classification 31-A1) of the femur by using optimized finite element analysis.Study Design:Biomechanical study.Methods:Computed tomography images of patients’ right femurs were processed with Mimics. Afterwards a solid femur model was created with SolidWorks 2015 and transferred to ANSYS Workbench 16.0 for response surface optimization analysis which was carried out according to anterior-posterior (-10°0) and posterior-anterior directions of the femur neck significantly increased these stresses. The most suitable position of the proximal lag screw was confirmed as the middle of the femoral neck by using optimized finite element analysis.

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It was found that the maximum von Mises stress on the canine femur shaft was 34.8 MPa. Stress and accuracy values were obtained from the model formed using the Rapidform software. The values obtained were similar to those in other studies in the literature.

Reverse engineering methods are important for remodeling or measuring damaged or non-damaged parts. Reverse engineering also enables the design of complex components, reducing actual product production time and prototype production time. With this method, damaged gear wheels can be modeled in a short time due to the regular geometry and symmetrical properties of the teeth and it is real models can be produced. In this study, the damaged motor cam gear was scanned with a three dimensional (3D) scanner and a mesh model was formed. Then, solid model of part was created and genuine prototype was produced with 3D printer. The deviations of geometric dimensions between the mesh model and the solid model were analyzed and the levels of convergence were determined. The three-dimensional prototyping method provides great convenience for the designer due to it gives quick feedback in product development process. At the end of the study, geometric values between solid model and prototype model were compared and deviations from actual value were determined.

The deviation values obtained by matching models created by three different methods showed statistically significant results (P < 0.05). Values obtained from the CT-Breuckmann model were lower than those obtained from CT-Metris. In order to lower deviation values, applications such as increasing the resolution of images, using stronger algorithms, meshing methods and enhancing surface form should be implemented.