Sharif Digital Repository

Successful treatment of bone infections is a major orthopedic challenge due to the physiological and anatomical features of bone. In this project, we prepared a drug delivery system with injectable and biodegradable polysaccharide agar containing alginate, polyvinyl alcohol and hydroxyapatite nanocarriers composite microspheres. Alginate and polyvinyl alcohol composite microspheres are crosslinked by calcium and freeze-thawing technique. Using the freeze thawing process for polyvinyl alcohol crosslinking, in addition to alginate crosslinking, improved hydrogel swelling behavior and enhanced drug loading and thus slowed drug release, drug loading increased with increasing PVA percentage from ... 

Loosening and gap opening at the bone-implant interface depends on several physiological and mechanical factors such as bone remodeling, stress concentration, and variation in load transfer pathway. Since fracture of orthopedic material at the interface is one of the major failure mode of total joint implants, this study focused on the micromechanical behavior of the interface. Using a two-dimensional FE model, with pure compressive, tensile, and shearing forces applied on bone or cement, ratio of the stress at the interface to the applied stress has been calculated. Stress distribution was considered as a function of porosity,angle of bead contact to surface, as well as size of bead for two... 

In the last decade, mechanical metamaterials have attracted more attention due to new design principles that combine the concept of hierarchical architecture with material size effects at the micro or nano scale. This strategy shows extraordinary mechanical performance that we use in unknown parts of the material property space, including strength-to-density ratios, extraordinary flexibility, and the ability to absorb energy with brittle components. The aim of this research was to print metamaterial scaffolds from a combination of biocompatible and bioactive to be used as scaffolds in bone tissue engineering. In addition to the biological properties appropriate to the host tissue, the... 

Modified Fish-Bone (MFB) Model and Consistent Generic (CG) Model are simplified Multi-Degrees-of-Freedom (MDOF) models, proven to be valuable tools in estimating seismic demands of moment-resisting frames, aimed to reduce the computational costs by decreasing the number of degrees of freedom. The preliminary expansion of these simplified models for steel moment resisting frames (SMRFs) were proposed by considering elastoplastic behavior and is not able to take into account stiffness and strength deteriorations in nonlinear dynamic behavior of structures. However, behavior deterioration affects seismic demands of SMRFs under intense earthquakes. For this reason, the present study is done to... 

BASHTI is a new implant-less ACL reconstruction surgery which has recently been considered for its advantages. This study aimed to investigate the effects of tendon and cannulated drill bit diameter on the BASHTI fixation strength and core bone engaged length (CBEL) in an anterior cruciate ligament (ACL) reconstruction. It is believed that CBEL may affect both bone healing process and fixation strength in this technique. Bovine digital tendons and Sawbones blocks were used to mimic the ACL reconstruction. Tendons were sized to 6, 7, 8, 9, and 10 mm and the hole size for the 6-9 mm tendons was set to 10 mm while for the 10 mm tendon was set to 12 mm. Mechanical strength of the specimens was... 

Craniofacial bone defects without scarring are a major clinical issue. These critical defects, which can be caused by infection or fracture, cannot be repaired without surgery. The main goal of skull repair is to protect vulnerable structures such as the brain, or it can be due to the improvement of jaw function and beauty. Tissue engineering can offer a new generation solution. The purpose of this study was to construct and characterise a degradable polymer/ bioceramic composite scaffold with allograft powder used in the craniofacial bone. The complexities of the extracellular matrix of humans can be simulated using 3D bioprinting.In this study, tricalcium silicate (TCS) was first... 

In the upcoming research, with the aim of bone tissue engineering and achieving a new structure, a scaffold based on polyhema (PHEMA) and gelatin (Gel), which are biocompatible polymers for bone tissue, was made and evaluated. Also, in order to improve the bioactivity and mechanical properties, bioactive glass alone (BG45S5) or together with strontium (BG-Sr) was used in the scaffold structure. and chemical by conducting FTIR, XRD, SEM, mechanical strength, bioactivity measurement, contact angle, water absorption and degradation tests. Biological investigations were done using mesenchymal stem cells derived from human bone marrow and with the help of MTT evaluations and SEM photography. The...