Investigation of effective coating of the Ti-6Al-4V alloy and 316L stainless steel with graphene or carbon nanotubes with finite element methods

Tumer, Devrim/0000-0003-2806-7648WOS:000606462600011Background: The Ti-6Al-4V alloy and 316L stainless steel are widely used biocompatible implant materials for repairing bone fractures and their mechanical properties are now being considered for various other applications. Due to the mentioned reasons, we initially investigated and determined the mechanical effects of these biocompatible implant materials. in the sequel, as a novelty of this study, we adopted a unique approach to investigating these materials and sought to determine if coating the Ti-6Al-4V alloy and 316L stainless steel with graphene or carbon nanotubes (CNTs) could provide superior mechanical properties compared to when their surface is uncoated. Methods: To investigate the mechanical effects of the Ti-6Al-4V alloy and 316L stainless, finite element method was utilized. Finite element analyses (FEAs) of the Ti-6Al-4V alloy and 316L stainless steel samples were comparatively conducted with the numerical results in literature. Static structural analyses were generated for the externally fixated femur in the single-leg stance position. Comparative static load analyses were performed for six distinctive cases of the uncoated Ti-6Al-4V alloy and 316L stainless steel, and graphenecoated Ti-6Al-4V alloy, CNT-coated Ti-6Al-4V alloy, graphene-coated 316L stainless steel, and CNT-coated 316L stainless steel. Results: The results of the static load analyses of the six distinctive cases show that the uncoated Ti-6Al-4V, graphene-coated Ti-6Al-4V, and CNT-coated Ti-6Al-4V samples stress values are 48.29 MPa, 36.24 MPa, and 87.574 MPa for the femur, the first screw, and plate stresses, respectively. These stresses are the minimum stress values occurred on the femur, the first screw, and the plate, respectively. on the other hand, the graphene-coated 316L and CNT-coated 316L stainless steel samples had the minimum displacement values, which were obtained as 1.558 mm, 1.5576 mm at the femoral head, and 0.13029 mm, 0.13028 mm at the fracture line, respectively. Conclusion: The main result and conclusion of this study is that coating the Ti-6Al-4V alloy and 316L stainless steel samples with graphene or CNTs results in superior mechanical performance in comparison to when they are uncoated. Considering the FEAs of the six different materials, CNT- or graphene-coated Ti-6Al-4V and CNT- or graphene-coated 316L stainless steel are the most recommended finite element models (FEMs) in terms of stress and displacement values, respectively. By using CNT- or graphene-coated Ti-6Al-4V and CNT- or graphene-coated 316L stainless steel, more durable, stable externally fixated implants can be obtained for femoral shaft fractures in terms of stress and displacement reduction occurred on both femur and implants. (C) 2020 The Author(s). Published by Elsevier B.V

Evaluation of bone plate with low-stiffness material in terms of stress distribution

WOS: 000261657000020PubMed ID: 18805533The aim of this study is to evaluate a newly developed bone plate with low-stiffness material in terms of stress distribution. In this numerical study, 3D finite element models of the bone plate with low-stiffness material and traditional bone plates made of stainless steel and Ti alloy have been developed by using the ANSYS software. Stress analyses have been carried out for all three models under the same loading and boundary conditions. Compressive stresses occurring in the intact portion of the bone (tibia) and at the fractured interface at different stages of bone healing have been investigated for all three types of bone-plate systems. The results obtained have been compared and presented in graphs. It has been seen that the bone plate with low-stiffness material offers less stress-shielding to the bone, providing a higher compressive stress at the fractured interface to induce accelerated healing in comparison with Ti alloy and stainless-steel bone plate. In addition, the effects of low-stiffness materials with different Young's modulus on stress distribution at the fractured interface have been investigated in the newly developed bone-plate system. The results showed that when a certain value of Young's modulus of low-stiffness material is exceeded, increase in stiffness of the bone plate does not occur to a large extent and stress distributions and micro-motions at the fractured interface do not change considerably. (C) 2008 Elsevier Ltd. All rights reserved

In vivo investigation of calcium phosphate coatings on Ti6-Al-4V alloy substrates using lactic acid - sodium lactate buffered synthetic body fluid

WOS: 000333317900008PubMed ID: 24509222Objective: The aim of this study was to evaluate the mode of failure and biomechanical characteristics of Ti-6Al-4V anchors biomimetically coated with calcium phosphate (CaP) for soft tissue fixation to bone in an animal model. Methods: The current study included 14 adult New Zealand white rabbits equally divided into two groups. Calcium phosphate-coated Ti-6Al-4V anchors were used in the test group and non-coated Ti-6Al-4V anchors in the control group. Anew approach was applied to synthesize the CaP coatings via the biomimetic growth in the Lac-SBF containing Ca2+ and PO43- ions, Na-lactate and lactic acid (HL). Titanium anchors were implanted into the right tibia, followed by biomechanical tensile strength tests. Histological studies were carried out after removal of anchors (bone-implant surface). Results: The CaP-coated Ti-6Al-4V anchors had significantly higher tensile strength (p=0.003) and displacement values (p=0.004) than the non-coated anchors. Control group scores were higher than those of the test group (14 and 9, respectively) in tensile strength tests. Conclusion: The new CaP coating can be used in orthopedic surgery as catalyzer to improve bone ingrowth. We believe that our research will form a model for further research on biomimetic coatings on Ti-6Al-4V substrates.State Planning Foundation of TurkeyTurkiye Cumhuriyeti Kalkinma Bakanligi [06-DPT-002]; EBILTEM, Izmir, TurkeyEge UniversityThis study was funded by the State Planning Foundation of Turkey (Project No: 06-DPT-002). The authors thank EBILTEM, Izmir, Turkey, for their financial support

Operative treatment of chondroblastoma : a study of 11 cases

Aim of the study was to review the radiological, clinical results of 11 chondroblastoma cases treated at our institute between 2003-2013. All patients with chondroblastoma included in this study underwent intralesional curettage +/- bone grafting. Follow up for healing of chondroblastoma lesions and detection of any local recurrence was assessed on clinical and radiological bases. The functional outcome was assessed by the Musculoskeletal Tumour Society scoring system. The mean follow-up period was 6.1 years. There were three recurrences (two femoral head, one proximal tibia). The mean Musculoskeletal Tumour Society functional score was 21. First line aggressive treatment seems appropriate for chondroblastoma especially when localized at lower extremities

A biomechanical study on preloaded compression effect on headless screws

WOS: 000271538400003PubMed ID: 19911480Commonly used headless design screws such as Acutrak and Herbert screws have limited compressive effect on short fragment fixation. Therefore, we investigated whether preloaded compression techniques could be helpful in improving the compression effect. A prototype of interfragmentary compression screw was designed with a constant pitch to avoid self-compressive effect. Preloaded compression was achieved with a sleeve device before the insertion of the trailer side (the leading side was inserted). Prototype screw test results were compared with those of Acutrak and Herbert screws. Eight pullout and eight compression tests were performed for each of the three screws using homogenous synthetic bone blocks. The mean pullout forces of the Acutrak, Herbert and prototype screws were 67.21, 45.90 and 61.88 N, respectively. Preloaded compression (18.15 N) was higher than the compression produced by Acutrak (15.27 N) and Herbert (15.11 N) screws (p < 0.05). However, at the end of full insertion, half of the power obtained by preloaded compression was lost. Preloaded compression technique was successful in attaining maximum compression rate. During trailing-side insertion, constant pitch design failed to keep compression rate. Variable pitches can be useful to preserve or increase compression rate. In addition, sleeve usage may be more advantageous in thin fragment fixation

Anatomic implications of lesser trochanterplasty

Objective: The aim of this study was to measure the area of iliopsoas tendon attachment and the distance of sciatic nerve, medial circumflex femoral artery (MCFA) and quadratus muscle to lesser trochanter tip, before and after 5, 10, 15 mm depth excision of lesser trochanter

Biocompatibility of MG-63 cells on collagen, poly-L-lactic acid, hydroxyapatite scaffolds with different parameters

WOS: 000362370500002PubMed ID: 24744232Purpose: In this study, osteoblast-like MG-63 cells were cultured on 3 different scaffold types composed of (a) collagen + poly-L-lactic acid (PLLA), (b) collagen + hydroxyapatite (HA; 30 degrees C) or (c) collagen + hydroxyapatite (HA; 37 degrees C) and produced with different porosities. Methods: Biomechanical properties of the scaffolds were characterized by tensile strength measurements. Properties of the cell-seeded scaffolds were evaluated with scanning electron microscopy (SEM). Cell adhesion and proliferation capacities were evaluated. Alkaline phosphatase (ALP) levels in media were measured. Transmission electron microscopy (TEM) and histological analyses were used to assess morphological characteristics. Results: Our results showed that collagen-based PLLA and HA scaffolds have good cell biocompatibility. MTT test showed that the scaffolds exhibited no cytotoxicity. According to the force and displacement data, collagen + HA at 37 degrees C showed the highest mechanical strength and displacement. Conclusion: The results suggest that collagen-based PLLA and HA scaffolds might improve osteoblastic growth in vitro and have biomaterial integration potential in possible therapeutic approaches for future clinical studies

TO COMPARE THE DIFFERENT SCAFFOLDS ACCORDING TO POROSITY'S PROPERTIES

14th National Biomedical Engineering Meeting -- MAY 20-22, 2009 -- Izmir, TURKEYWOS: 000274345400076The main purpose of this study is to investigate the increase in osteoblast cells cultured on three different porosity scaffolds in vivo environment. Hence, Collagen + Poly-l-lactic acid (PLLA), Collagen +HA (30 C degrees), Collagen + HA (37 C degrees) were studied. During the operation, 20 ml bone marrow was taken for any of patient in sterile conditions. Mesenchymal stem cells were differentiated to osteoblast cells. After the ALP and morphological evaluations were assessed, osteoblast cells were planted on 3 different scaffolds and SEM observations were evaluated. At twenty-fifth day, konfleunt osteoblast cells were observed. Osteoblast cells were watched on Collagen + HA (30 C degrees) scaffold appropriately. According to our knowledge, in various bone defects, cell cultures on suitable scaffolds are contribute to clinical studies