Revealing the compressive and flow properties of novel bone scaffold structure manufactured by selective laser sintering technique

Additive manufacturing is revolutionizing the field of medical sciences through its key application in the development of bone scaffolds. During scaffold fabrication, achieving a good level of porosity for enhanced mechanical strength is very challenging. The bone scaffolds should hold both the porosity and load withstanding capacity. In this research, a novel structure was designed with the aim of the evaluation of flexible porosity. A CAD model was generated for the novel structure using specific input parameters, whereas the porosity was controlled by varying the input parameters. Poly Amide (PA 2200) material was used for the fabrication of bone scaffolds, which is a biocompatible material. To fabricate a novel structure for bone scaffolds, a Selective Laser Sintering machine (SLS) was used. The displacement under compression loads was observed using a Universal Testing Machine (UTM). In addition to this, numerical analysis of the components was also carried out. The compressive stiffness found through the analysis enables the verification of the load withstanding capacity of the specific bone scaffold model. The experimental porosity was compared with the theoretical porosity and showed almost 29% to 30% reductions when compared to the theoretical porosity. Structural analysis was carried out using ANSYS by changing the geometry. Computational Fluid Dynamics (CFD) analysis was carried out using ANSYS FLUENT to estimate the blood pressure and Wall Shear Stress (WSS). From the CFD analysis, maximum pressure of 1.799 Pa was observed. Though the porosity was less than 50%, there was not much variation of WSS. The achievement from this study endorses the great potential of the proposed models which can successfully be adapted for the required bone implant applications.

Biomechanical Analysis and Design Method for Patient-Specific Reconstructive Implants for Large Bone Defects of the Distal Lateral Femur

This study aims to develop a generalizable method for designing a patient-specific reconstructive scaffold implant for a large distal lateral femur defect using finite element (FE) analysis and topology optimization. A 3D solid-core implant for the distal femur defect was designed to withhold the femur load. Data from FE analysis of the solid implant were use for topology optimization to obtain a ‘bone scaffold implant’ with light-weight internal cavity and surface lattice features to allow for filling with bone material. The bone scaffold implant weighed 69.6% less than the original solid-core implant. The results of FE simulation show that the bone repaired with the bone scaffold implant had lower total displacement (12%), bone plate von Mises stress (34%), bone maximum first principal stress (33%), and bone maximum first principal strain (32%) than did bone repaired with bone cement. The trend in experimental strain with increasing load on the composite femur was greater with bone cement than with the bone scaffold implant. This study presents a generalizable method for designing a patient-specific reconstructive scaffold implant for the distal lateral femur defect that has sufficient strength and space for filling with allograft bone.

Penentuan Komposisi Hidroksiapatit-Alginat-Zinc terhadap Kuat Tekan Bone Scaffold dengan Metode Taguchi

Indonesia merupakan negara berkembang dengan tingkat mobilitas masyarakat yang berkendara cukup tinggi. Seiring dengan bertambahnya kebutuhan transportasi menyebabkan tingkat kecelakaan lalu lintas juga semakin meningkat. Permasalahan ini menyebabkan luka hingga patah tulang bagi para korban. Untuk menangani masalah tersebut, perlu diadakannya pencangkokan tulang (bone graft). Pada penelitian ini akan dirancang material tulang pengganti manusia yang berasal dari campuran Hidroksiapatit dengan Alginat dan Zinc. Hasil pencampuran material akan dilakukan pengujian kuat tekan dan data akan diolah dengan menggunakan metode Taguchi. Target uji tekan yaitu 7,5-41 MPa dengan karakteristik kualitas larger-the-better. Sedangkan desain eksperimen yang digunakan yaitu L423. Hasil dari perhitungan ANOVA menunjukkan bahwa faktor komposisi HA, komposisi Alginat, dan rasio HA:Aquades memiliki hasil yang signifikan. Terhadap kuat tekan scaffold. Namun, hasil perhitungan ANOVA terhadap nilai SNR menunjukkan bahwa ketiga faktor tersebut tidak memiliki kontribusi pada pengurangan variansi suatu karakteristik kualitas. Komposisi material scaffold yang paling optimal yaitu komposisi HA 88%wt, komposisi Alginat 8%wt, dan rasio HA:Aquades 1:1,5. Hasil nilai kuat tekan pada komposisi tersebut sebesar 8,197±0,259 MPa dimana nilai ini sesuai dengan nilai kuat tekan untuk tulang cancellous.

Role of miR-214 in biomaterial transplantation therapy for osteonecrosis

BACKGROUND: The effectiveness and availability of conservative therapies for osteonecrosis of the femoral head (ONFH) are limited. Transplantation of bone marrow mesenchymal stem cells (BMSCs) combined with Bio-Oss, which is a good bone scaffold biomaterial for cell proliferation and differentiation, is a new potential therapy. Of note, the expression of miRNAs was significantly modified in cells cultured with Bio-Oss, and MiR-214 was correlated positively with osteonecrosis. Furthermore, miR-214 was upregulated in cells exposed to Bio-Oss. OBJECTIVE: To investigate whether targeting miR-214 further improves the transplantation effect. METHODS: We treated BMSCs with agomiR-214 (a miR-214 agonist), antagomiR-214 (a miR-214 inhibitor), or vehicle, followed by their transplantation into ONFH model rats. RESULTS: Histological and histomorphometric data showed that bone formation was significantly increased in the experimental groups (Bio-Oss and BMSCs treated with antagomiR-214) compared with other groups. CONCLUSIONS: miR-214 participates in the inhibition of osteoblastic bone formation, and the inhibition of miR-214 to bone formation during transplantation therapy with Bio-Oss combined with BMSCs for ONFH.

Mechanical Performance of 3D-Printed Biocompatible Polycarbonate for Biomechanical Applications

Additive manufacturing has experienced remarkable growth in recent years due to the customisation, precision, and cost savings compared to conventional manufacturing techniques. In parallel, materials with great potential have been developed, such as PC-ISO polycarbonate, which has biocompatibility certifications for use in the biomedical industry. However, many of these synthetic materials are not capable of meeting the mechanical stresses to which the biological structure of the human body is naturally subjected. In this study, an exhaustive characterisation of the PC-ISO was carried out, including an investigation on the influence of the printing parameters by fused filament fabrication on its mechanical behaviour. It was found that the effect of the combination of the printing parameters does not have a notable impact on the mass, cost, and manufacturing time of the specimens; however, it is relevant when determining the tensile, bending, shear, impact, and fatigue strengths. The best combinations for its application in biomechanics are proposed, and the need to combine PC-ISO with other materials to achieve the necessary strengths for functioning as a bone scaffold is demonstrated.