Stents With Torsional Strength for Superficial Femoral Artery Disease: The Prospective Q3-Registry

Purpose: This postmarketing surveillance study aimed to assess effectiveness and safety of a peripheral self-expanding stent with high torsional strength (POLARIS stent) for the treatment of de novo superficial femoral artery (SFA) lesions in the routine clinical practice. Materials and Methods: Consecutive patients with symptomatic de novo SFA occlusive disease who underwent POLARIS stent implantation were enrolled into the prospective, multicenter, observational postmarket surveillance study. Primary outcome measure was freedom from clinically driven target lesion revascularization (cdTLR) at 12 months. Main secondary outcomes were procedural success, primary clinical improvement, and freedom from major adverse cardiovascular and limb events (MACLE) throughout 24 months. Results: A total of 199 participants (70±11 years, 70.4% men) were included in the study at 9 German sites from December 2014 to August 2018. Half of them (52.6%) were current smokers, 37.6% had diabetes, and 25.0% were obese. Most participants suffered from intermittent claudication (88.4%). Mean lesion length was 98±83 mm, 43.5% of lesions were occluded, and 27.3% were severely calcified. Freedom from 12 months cdTLR was 94.4% (95% confidence interval [CI], 90.6–98.2). At 24 months, freedom from cdTLR was 88.7% (95% CI, 83.0–94.4). Procedural success was achieved in 96.2% of participants. Primary clinical improvement occurred in 87.5% and 85.4% of participants at 12 and 24 months, respectively. Freedom from MACLE was 94.8% (95% CI, 91.4–98.1) and 93.8% (95% CI, 89.9–97.6) at 12 and 24 months, respectively. Conclusions: Treatment of SFA occlusive disease in a real-world setting using the POLARIS stent with high bidirectional torsional strength is efficacious and does not raise any safety concern in the medium term. The study is registered with ClinicalTrials.gov (Identifier: NCT02307292).

A Comparative Investigation on Normal and High Strength Concrete Beams under Torsion

In this study, an experimental investigation was done to study the behaviour of Normal Strength Concrete (NSC) and High Strength Concrete (HSC) Plain beams under torsion with the concrete mix of M40 and M100. No mineral admixtures are used to obtain the required strength of concrete. Eight NSC beams and eight HSC beams whose width was varying with 75 mm, 100 mm, and 150 mm; depth varying as 75 mm, 100 mm, 150 mm and 200 mm; and span of the beams varying 600 mm, 800 mm and 1200 mm were casted and cured to stud the effect of torsion. The principle aim of this study was to understand the torsional behaviour of the NSC and HSC beams for rotation, cracking, size effect and torsional strength. A standard torsional loading method was used for conducting the testing of beams. The results obtained were compared with different theories and code equations. It was observed that the torsional strength of the beam increases with the increase in strength of concrete. HSC beams have higher torsional strength than the NSC beams which has the same amount of reinforcement.

Strength and fracture mechanism during torsion of ultrafine-grained austenitic steel for medical applications

The article considers evaluation of torsional strength and fracture of austenitic corrosion-resistant steel 08Kh18N9 with an ultrafine-grained (UFG) and coarse-grained (CG) structure, widely used in medicine for the production of plates, screws, rods for bone osteosynthesis and other medical products. The structure of the CG steel was studied using an Axiovert 40 MAT metallographic microscope, and the fine structure of the UFG steel was investigated with a JEM-2100 transmission electron microscope. Torsion tests of the cylindrical samples with a diameter of 10 mm were carried out at a temperature of 20 °C on MK-50 installation. JEOL JCM-6000 scanning electron microscope was used for the microfractographic studies of fracture surfaces. The analysis of the “Torque - torsion angle” diagrams showed that the torsional ultimate strength (τt) and yield strength (τ0.3) of UFG steel increase by 1.3 - 3.8 times, and the relative shear (g) decreases by 2.4 times in comparison with CG steel. High values of torsional strength properties of UFG steel make it possible to provide high torque without destroying the product. Consequently UFG steel 08Kh18N9 in comparison with CG steel is a more promising material for the manufacture of medical screws and other medical products that experience significant loads during the torsion process. Three areas were identified on the surface of all fractures: fibrous central part, transitional (middle) part, and a relatively smooth peripheral part. Fracture begins with the formation of shear pits in the middle and peripheral parts, which, with further rotation of the sample, are completely rubbed out (in case CG steel), or remain (in case of UFG steel). Final failure occurs under the action of normal stresses in the central part of the sample.