The Characteristics of Nitinol in Spinal Implant Manufacturing

: Due to the increasing number of diseases related to the spine, we expect to see more research on the implants used in this area. These implants should have features such as strength, fatigue resistance, chemical stability and biocompatibility, which fortunately are seen in an alloy called nitinol. In this study, six lumbar vertebral implants were made of nitinol and these samples been studied by some experiments such as: X-ray diffraction and biocompatibility (evaluation of cytotoxicity by MTT assay). Finally, we came to the conclusion that the mentioned alloy with suitable microstructure is appropriate for medical applications specially as an orthopedic implant. According to the X-ray diffraction pattern, the samples have austenitic structures in the room temperature and the predominant phase of the porous sample is B2-NiTi. Since the sample should be biocompatible after placement in the body and should not cause an immune system reaction, this test was also examined and the samples were tested in vitro with an MTT kit and the biocompatibility was assessed. The results of biocompatibility tests also indicate the suitability of the implant in terms of cellular characteristics. These properties have made this alloy superior to other alloys in orthopedic implant utilization, especially in areas under continuous loading. It is hoped that the construction of this type of implant will pave the way for facilitating the treatment of spinal abnormalities.

Synthesis and Characterization of Ti-Sn Alloy for Orthopedic Application

Titanium (Ti)-based alloys (e.g., Ti6Al4V) are widely used in orthopedic implant applications owing to their excellent mechanical properties and biocompatibility. However, their corrosion resistance needs to be optimized. In addition, the presence of aluminum and vanadium cause alzheimer and cancer, respectively. Therefore, in this study, titanium-based alloys were developed via powder metallurgy route. In these alloys, the Al and V were replaced with tin (Sn) which was the main aim of this study. Four sets of samples were prepared by varying Sn contents, i.e., 5 to 20 wt. %. This was followed by characterization techniques including laser particle analyzer (LPA), X-ray diffractometer (XRD), scanning electron microscope (SEM), computerized potentiostate, vicker hardness tester, and nanoindenter. Results demonstrate the powder sizes between 50 and 55 µm exhibiting very good densification after sintering. The alloy contained alpha at all concentrations of Sn. However, as Sn content in the alloy exceeded from 10 wt. %, the formation of intermetallic compounds was significant. Thus, the presence of such intermetallic phases are attributed to enhanced elastic modulus. In particular, when Sn content was between 15 and 20 wt. % a drastic increase in elastic modulus was observed thereby surpassing the standard/reference alloy (Ti6Al4V). However, at 10 wt. % of Sn, the elastic modulus is more or less comparable to reference counterpart. Similarly, hardness was also increased in an ascending order upon Sn addition, i.e., 250 to 310 HV. Specifically, at 10 wt. % Sn, the hardness was observed to be 250 HV which is quite near to reference alloy, i.e., 210 HV. Moreover, tensile strength (TS) of the alloys were calculated using hardness values since it was very difficult to prepare the test coupons using powders. The TS values were in the range of 975 to 1524 MPa at all concentrations of Sn. In particular, the TS at 10 wt. % Sn is 1149 MPa which is comparable to reference counterpart (1168 MPa). The corrosion rate of Titanium-Sn alloys (as of this study) and reference alloy, i.e., Ti6Al4V were also compared. Incorporation of Sn reduced the corrosion rate at large than that of reference counterpart. In particular, the trend was in decreasing order as Sn content increased from 5 to 20 wt. %. The minimum corrosion rate of 3.65 × 10−9 mm/year was noticed at 20 wt. % than that of 0.03 mm/year of reference alloy. This shows the excellent corrosion resistance upon addition of Sn at all concentrations.

A DESCRIPTIVE STUDY OF BACTERIOLOGICAL SPECTRUM OF ORTHOPEDIC IMPLANT INFECTION IN CLOSED FRACTURES

Background: Surgical Site Infection (SSI) is defined as pain associated with erythema, induration, local tenderness, pus discharge or any culturepositive or negative discharge from a surgically created wound. Methods: Hospital based Descriptive type of Observational study conducted on Patients in the department of Orthopaedics. Results: Total 5.00% patients have wound infection. Gram positive 80.00% patients have found with Staph. Aureus and Gram negative 20.00%patients have found with Pseudomonas. Conclusion: Infection in closed fractures with implants was quite high. The adverse outcome of SSIs related to a clean orthopedic surgical procedure can be associated with significant morbidity, cost, and even mortality. Keywords: Infection, SSI, Fracture

Methodology of Multicriterial Optimization of Geometric Features of an Orthopedic Implant

The main purpose of the article is to describe the methodology used for multi-criteria optimization of the geometric features of the orthopedic implant used for the reconstruction of the anterior cruciate ligament located in the knee joint. The methodology includes: 1. Method of development of the bones of the knee joint model; 2. Method of multi-criteria optimization of the geometric features of the orthopedic implant using an artificial immune system, the objective function and the Pareto front; 3. Expert evaluation method based on forms. The work confirmed that the assumed thesis, a multi-criteria optimization using an artificial immune system, which is a specially defined objective function, and the Pareto method, which allows to determine the geometrical features of the implant, will lead to fulfill optimal blood perfusion and sufficient strength properties of the implant simultaneously. We conclude that the described methodology allowed to achieve the optimal geometrical features of the orthopedic implant used for reconstruction of the anterior cruciate ligament located in the knee joint.

Antibacterial and Anti-Inflammatory Coating Materials for Orthopedic Implants: A Review

Orthopedic implant failure is the most common complication of orthopedic surgery, causing serious trauma and resulting in a tremendous economic burden for patients. There are many reasons for implant failure, among which peri-implant infection (or implant-related infection) and aseptic loosening are the most important. At present, orthopedic doctors have many methods to treat these complications, such as revision surgery, which have shown good results. However, if peri-implant infection can be prevented, this will bring about significant social benefits. Many studies have focused on adding antibacterial substances to the implant coating, and with a deeper understanding of the mechanism of implant failure, adding such substances by different modification methods has become a research hot spot. This review aims to summarize the antibacterial and anti-inflammatory substances that can be used as coating materials in orthopedic implants and to provide a reference for the prevention and treatment of implant failure caused by implant-related infection and excessive inflammation.

Antimicrobial Peptides in the Battle against Orthopedic Implant-Related Infections: A Review

Prevention of orthopedic implant-related infections is a major medical challenge, particularly due to the involvement of biofilm-encased and multidrug-resistant bacteria. Current therapies, based on antibiotic administration, have proven to be insufficient, and infection prevalence may rise due to the dissemination of antibiotic resistance. Antimicrobial peptides (AMPs) have attracted attention as promising substitutes of conventional antibiotics, owing to their broad-spectrum of activity, high efficacy at very low concentrations, and, importantly, low propensity for inducing resistance. The aim of this review is to offer an updated perspective of the development of AMPs-based preventive strategies for orthopedic and dental implant-related infections. In this regard, two major research strategies are herein addressed, namely (i) AMP-releasing systems from titanium-modified surfaces and from bone cements or beads; and (ii) AMP immobilization strategies used to graft AMPs onto titanium or other model surfaces with potential translation as coatings. In overview, releasing strategies have evolved to guarantee higher loadings, prolonged and targeted delivery periods upon infection. In addition, avant-garde self-assembling strategies or polymer brushes allowed higher immobilized peptide surface densities, overcoming bioavailability issues. Future research efforts should focus on the regulatory demands for pre-clinical and clinical validation towards clinical translation.