Investigation of contact behavior on a model of the dual-mobility artificial hip joint for Asians in different inner liner thicknesses.

BACKGROUND: The four components that make up the current dual-mobility artificial hip joint design are the femoral head, the inner liner, the outer liner as a metal cover to prevent wear, and the acetabular cup. The acetabular cup and the outer liner were constructed of 316L stainless steel. At the same time, the inner liner was made of ultra-high-molecular-weight polyethylene (UHMWPE). As this new dual-mobility artificial hip joint has not been researched extensively, more tribological research is needed to predict wear. The thickness of the inner liner is a significant component to consider when calculating the contact pressure. AIM: To make use of finite element analysis to gain a better understanding of the contact behavior in various inner liner thicknesses on a new model of a dual-mobility artificial hip joint, with the ultimate objective of determining the inner liner thickness that was most suitable for this particular type of dual-mobility artificial hip joint. METHODS: In this study, the size of the femoral head was compared between two diameters (28 mm and 36 mm) and eight inner liner thicknesses ranging from 5 mm to 12 mm. Using the finite element method, the contact parameters, including the maximum contact pressure and contact area, have been evaluated in light of the Hertzian contact theory. The simulation was performed statically with dissipated energy and asymmetric behavior. The types of interaction were surface-to-surface contact and normal contact behavior. RESULTS: The maximum contact pressures in the inner liner (UHMWPE) at a head diameter of 28 mm and 36 mm are between 3.7-13.5 MPa and 2.7-10.4 MPa, respectively. The maximum von Mises of the inner liner, outer liner, and acetabular cup are 2.4-11.4 MPa, 15.7-44.3 MPa, and 3.7-12.6 MPa, respectively, for 28 mm head. Then the maximum von Mises stresses of the 36 mm head are 1.9-8.9 MPa for the inner liner, 9.9-32.8 MPa for the outer liner, and 2.6-9.9 MPa for the acetabular cup. A head with a diameter of 28 mm should have an inner liner with a thickness of 12 mm. Whereas the head diameter was 36 mm, an inner liner thickness of 8 mm was suitable. CONCLUSION: The contact pressures and von Mises stresses generated during this research can potentially be exploited in estimating the wear of dual-mobility artificial hip joints in general. Contact pressure and von Mises stress reduce with an increasing head diameter and inner liner's thickness. Present findings would become one of the references for orthopedic surgery for choosing suitable bearing geometric parameter of hip implant.

Running-in behavior of dual-mobility cup during the gait cycle: A finite element analysis.

The running-in process is considered an essential aspect of the comprehensive wear process. The phenomenon of running-in occurs during the initial stages of wear in the prosthetic hip joint. Within the field of tribology, the running-in phenomenon of the hip joint pertains to the mechanism by which the contact surfaces of the artificial hip joint components are adjusted and a suitable lubricating film is formed. During the process of hip joint running-in, there is an interaction between the metal surface of the ball and the joint cup, which results in adjustments being made until a steady state is achieved. The achievement of desirable wear existence and reliable performance of artificial hip joint components are reliant upon the tribological running-in of the hip joint. Despite the establishment of current modeling approaches, there remains a significant lack of understanding concerning running-in wear, particularly the metal-on-polyethylene (MoP) articulations in dual-mobility cups (DMC). An essential aspect to consider is the running-in phase of the dual mobility component. The present study employed finite element analysis to investigate the running-in behavior of dual mobility cups, wherein femoral head components were matched with polyethylene liners of varying thicknesses. The analysis of the running-in phase was conducted during the normal gait cycle. The results of this investigation may be utilized to design a dual-mobility prosthetic hip joint that exhibits minimal running-in wear.

Influence of Varying Concentrations of Epoxy, Rice Husk, Al2O3, and Fe2O3 on the Properties of Brake Friction Materials Prepared Using Hand Layup Method.

Brake friction materials (BFMs) have a critical role in ensuring the safety as well as the reliability of automotive braking systems. However, traditional BFMs, typically made from asbestos, are associated with environmental and health concerns. Therefore, this results in a growing interest in developing alternative BFMs that are eco-friendly, sustainable, and cost-effective. This study investigates the effect of varying concentrations of epoxy, rice husk, alumina (Al2O3), and iron oxide (Fe2O3) on the mechanical and thermal properties of BFMs prepared using the hand layup method. In this study, the rice husk, Al2O3, and Fe2O3 were filtered through a 200-mesh sieve. Note that the BFMs were fabricated using different combinations and concentrations of the materials. Their mechanical properties, such as density, hardness, flexural strength, wear resistance, and thermal properties, were investigated. The results suggest that the concentrations of the ingredients significantly influence the mechanical and thermal properties of the BFMs. A specimen made from epoxy, rice husk, Al2O3, and Fe2O3 with concentrations of 50 wt.%, 20 wt.%, 15 wt.%, and 15 wt.%, respectively, produced the best properties for BFMs. On the other hand, the density, hardness, flexural strength, flexural modulus, and wear rate values of this specimen were 1.23 g/cm3, 81.2 Vickers (HV), 57.24 MPa, 4.08 GPa, and 8.665 × 10-7 mm2/kg. In addition, this specimen had better thermal properties than the other specimens. These findings provide valuable insights into developing eco-friendly and sustainable BFMs with suitable performance for automotive applications.

Characterization of PLA/PCL/Green Mussel Shells Hydroxyapatite (HA) Biocomposites Prepared by Chemical Blending Methods.

Recently, there has been an increase in the number of studies conducted on the process of developing hydroxyapatite (HA) to use in biocomposites. HA can be derived from natural sources such as bovine bone. The HA usage obtained from green mussel shells in biocomposites in this study will be explored. The research goal is to investigate the composition effect of biomaterials derived from polycaprolactone (PCL), polylactic acid (PLA), as well as HA obtained from green mussel shells with a chemical blending method on mechanical properties and degradation rate. First, 80 mL of chloroform solution was utilized to immerse 16 g of the PLA/PCL mixture with the ratios of 85:15 and 60:40 for 30 min. A magnetic stirrer was used to mix the solution for an additional 30 min at a temperature and speed of 50 °C and 300 rpm. Next, the hydroxyapatite (HA) was added in percentages of 5%, 10%, and 15%, as well as 20% of the PLA/PCL mixture's total weight. It was then stirred for 1 h at 100 rpm at 65 °C to produce a homogeneous mixture of HA and polymer. The biocomposite mixture was then added into a glass mold as per ASTM D790. Following this, biocomposite specimens were tested for their density, biodegradability, and three points of bending in determining the effect of HA and polymer composition on the degradation rate and mechanical properties. According to the findings of this study, increasing the HA and PLA composition yields a rise in the mechanical properties of the biocomposites. However, the biocomposite degradation rate is increasing.

Application of fused deposition modeling (FDM) on bone scaffold manufacturing process: A review.

Some of the health issues that are becoming more prevalent each year include bone disease and fractures. Because the natural healing process of bones takes a long time, a bone grafting procedure is required so that the patient's condition can improve rapidly. Because bone grafting procedures such as autographs, allographs, and xenografts have limits, bone replacement is constructed by employing biomaterials in the form of a bone scaffold via additive manufacturing. As a result, fused deposition modeling (FDM) is a proposed technology for the manufacturing process because it is straightforward, capable of producing complex parts and adjustable shapes, and has minimal operational expenses. However, implementing this technique is challenging because of the scarcity of biocompatible and bioactive materials that are suited. This technology has a number of limitations, including a limited variety of biocompatible and bioactive materials, the most appropriate microarchitecture of bone scaffold, and the establishment of printing parameters that can produce bone scaffold with the strongest mechanical properties. This article discusses current advancements in the use of FDM technologies for bone scaffold production.

Synthesis and Characterization of Calcium Carbonate Obtained from Green Mussel and Crab Shells as a Biomaterials Candidate.

Green mussel and crab shells are natural sources of CaCO3, which is widely used as a bioceramic for biomedical applications, although they are commonly disposed of in landfills. The improper disposal of green mussel and crab shells can cause environmental pollution, reducing the quality of life in the community. Many studies have reported the preparation of CaCO3 from green mussels and crab shells. However, there are limited studies comparing the characteristics, including the crystal phase obtained, weight percentage (%) of crystal, crystal size, crystal system, and elemental composition of CaCO3 from green mussel shells, crab shells, and commercial CaCO3. The objective of this research was to compare the calcium carbonate properties formed from green mussel (PMS) and crab (PCS) shells to commercial CaCO3. Green mussel and crab shells were crushed to powder and were calcined at 900 °C for 5 h. Precipitated Calcium Carbonate (PCC) was synthesized from calcined green mussel and crab shells using a solution of 2M HNO3, NH4OH, and CO2 gas. The effect of setting parameters on the synthesized product was analyzed using XRD and SEM-EDX methods. This study shows that the chemical composition of PMS is nearly identical to that of commercial CaCO3, where no contaminants were identified. In contrast, PCS has N components other than Ca, C, and O. Furthermore, the predominance of the vaterite crystal phases in PMS and PCS, with respective weight percentages of 91.2% and 98.9%, provides a benefit for biomaterial applications. The crystallite sizes of vaterite in PMS, PCS, and calcite in commercial CaCO3 are 34 nm, 21 nm, and 15 nm, respectively.

Short communication: Running-in behavior on single-mobility total hip arthroplasty.

Total hip arthroplasty is a short-term solution for replacing a damaged hip joint with synthetic biomaterials. Total hip arthroplasty comes in two flavors: single and dual mobility. Mechanical and biological factors may degrade the quality of biomaterials over time. This may lead to implant failure and second surgical treatment. Wear is the crucial element leading to damaged bone and debris release throughout the body over time. Running-in is the initial wear phase between two surfaces before the steady-state phase. The stage of running-in is critical for understanding hip joint wear. Running-in and wear behavior have been extensively studied in single-mobility total hip arthroplasty, but aseptic loosening is the leading reason for restoration in arthroplasty registries. This paper seeks to summarize running-in behavior on single mobility hip implants, emphasizing its key aspects and recent developments.

Initial Response of Human Bone Marrow-Derived Stem Cells after Contact with Ultrahigh-Molecular-Weight Polyethylene (UHMWPE) Material: An In Vitro Study on Cell Viability and Interleukin-6 Expression.

INTRODUCTION: Ultrahigh-molecular-weight polyethylene (UHMWPE) is a thermoplastic polymer useful in biomaterial applications, especially in orthopedic field. Yet, little is known concerning its initial effect on human bone marrow stem cells (hBMSCs) after implantation. MATERIALS AND METHODS: A cytotoxicity analysis was performed with a 3-(4,5-dimethylthiazol 2-yl)-2,5-diphenyltetrazolium assay after 24, 48, and 72h of incubation of hBMSC culture. Expression of interleukin-6 (IL-6) was measured using enzyme-linked immunosorbent assay. Cell viability was measured with Inhibitory concentration 50% (IC50) formula. RESULTS: All treatment groups showed a cell viability of >50% ranging from 78% to >100%. Lower expression of IL-6 of hBMSC compared to control group was found in 48h of incubation period. CONCLUSION: hBMSC showed high cell viability after initial contact with UHMWPE material. Modulation of IL-6 expression was present at the initial stage as a response to foreign material.

Human Bone Marrow-Derived Mesenchymal Cell Reactions to 316L Stainless Steel: An in Vitro Study on Cell Viability and Interleukin-6 Expression.

Purpose: Human bone marrow-derived mesenchymal cell (hBMC) reactions to 316L stainless steel (316L-SS) have never been evaluated. The objective of this study was to assess cell viability and interleukin-6 expression of hBMC cultures upon treatment with a 316L-SS implant. Methods: A cytotoxicity analysis was conducted with a 3-(4,5-dimethylthiazol 2-yl)-2,5-diphenyltetrazolium (MTT) assay after a period of 24, 48 and 72 hours of incubation. Expression of interleukin-6 was measured using enzyme-linked immunosorbent assay (ELISA). Results: Cell viability measurement was performed via IC50 formula. All treatment group showed a > 50 % cell viability with a range of 56,5 - 96,9 % at 24 hours, 51,8-77,3% at 48 hours and 70,1- 120 % at 72 hours. Interleukin-6 expression was downregulated subsequent to treatment with 316L-SS compared to the control group. Conclusion: We found that 316L-SS did not exhibit toxicity towards hBMC culture.