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EN
Porous and alternative biografts for possible usages in orthopaedic applications were synthesized by the substitution of gelatin (G), cuttlefish backbone (C), meerschaum sepiolite (S) and hydroxyapatite (H). The effects of different proportions of the Gelatin substitutions on the mechanical properties and structure and cell viability properties of the fabricated biografts were investigated. Throughout the structure and mechanical evaluations, it was found that Gelatin substitution in the fabricated biografts increased the total porosity fraction, particularly for C13G75 and S13G75 biografts. Scanning Electron Microscope (SEM), X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) were used for characterization of the synthesized biografts. Furthermore, the cell viability tests for the synthesized biografts were carried out by using the osteoblast cell culture. Throughout the analysis, the synthesized C13G75 and S13G75 biografts generated the highest porosity and better correlation between mechanical properties and structural results contributing with highest cell viability rates.
EN
Laser-treated Ti6Al4V surfaces were coated by the single-layer hydroxyapatite (HA) and double-layer hydroxyapatite reinforced by the reduced nano-graphene oxide (rGO) using the sol-gel method. The effects of rGO reinforcement at different ratios and sintering temperatures on surface morphology and adhesion strength of the single and double layer coatings (rGO/HA) were analysed. As the initial treatment process, a laser texturing was patterned on the alloy and then, prepared samples were coated. The coated laser-modified HA and HA/rGO-coated Ti6Al4V surfaces were characterized by Raman spectroscopy, X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and the adhesion strength between the coat and substrates were determined by the standard adhesion tests. The conducted analyses indicated that the substitution of rGO into HA matrix revealed a homogeneous morphology and relatively crack-free coatings on the laser-treated Ti substrate surfaces. Adhesion tests showed that, the HA + rGO (1.0 wt. %) biocomposites exhibited a significant increase in adhesion strength compared to untreated surfaces and to the single HA-coated Ti6Al4V substrates.
EN
Purpose: Biomechanical comparison of straight DCP and helical plates for fixation of transversal and oblique tibial bone fractures were analyzed and compared to each other by axial compression, bending and torsion tests. Method: An in vitro osteosynthesis of transverse (TF) and oblique bone fracture (OF) fixations have been analysed on fresh sheep tibias by using the DCP and helical compression plates (HP). Results: Statistically significant differences were found for both DCP and helical plate fixations under axial compression, bending and torsional loads. The strength of fixation systems were in favor of DC plating with exception of the TF-HP fixation group under compression loads and torsional moments. The transvers fracture (TF) stability was found to be higher than that found in oblique fracture (OF) fixed by helical plates (HP). However, under torsional testing, compared to conventional plating, the helical plate fixations provided a higher torsional resistance and strength. The maximum stiffness at axial compression loading and maximum torsional strength was achieved at torsional testing for the TF-HP fixations. Conclusion: From in vitro biomechanical analysis, fracture type and plate fixation system groups showed different responses under different loadings. Consequently, current biomechanical analyses may encourage the usage of helical HP fixations in near future during clinical practice for transverse bone fractures.
EN
Due to temperature increase during bone drilling, bone necrosis is likely to occur. To minimize bone tissue damage during drilling, a detailed in vitro experimental study by using fresh calf cortical bones has been performed with various combined drilling parameters, such as: drilling environment, drill diameter, drill speed, drill force, feed-rate and drill coating. Bone temperatures at the drilling sites were recorded with high accuracy using multi-thermocouples mounted around the tibial diaphyseal cortex. It was shown that temperatures increased with increased drill speeds. It also decreased with a higher feed-rate and drill force. It was also observed that TiBN coated drills caused higher temperatures in the bone than the uncoated drills and the temperatures increased with larger drill diameters. Although the influence of Simulated Body Fluid (SBF) on rising temperatures during drilling was higher for the TiBN coated drills, it was observed that these drills caused more damage to the bone structure. In order to minimize or avoid bone defects and necrosis, orthopaedic surgeons should consider the optimum drilling parameters.
EN
A new method was used in fixation of tibial bone fractures. Intramadular nailing (IMN) has been used into mid-diaphysis on left tibias of New Zeland rabbits (n = 5) via an in vivo work. To enable fixation of fracture, without causing too much screw damage on bone and avoiding malunion, nano- and micro-scale hydroxyapatite (HA) was coated at two ends (25 mm in length) of intramadular nails before implantation. After six weeks of survival period and sacrifizing, biomechanical tests and histopathologic examinations were executed. Such experiments have revealed that good stabilization and hence better fracture union for both treated IMN groups (NHA and MHA) over the standard IMN’. Pull-out tests showed the tensile strengths obtained to be significantly higher for the nano (NHA) and micro scale-MHA coated IMN compared to the uncoated standard IM nailing.
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