Combined severe plastic deformation processing of commercial purity titanium enables superior fatigue resistance for next generation implants.

Commercial purity titanium (cp-Ti) is considered for replacing Ti64 as an implant material in various applications, due to the potential toxicity associated with the release of Al and V ions. However, the mechanical properties of cp-Ti, particularly fatigue resistance, are inadequate for this purpose. In this study, cp-Ti grade 4 rods were processed using a combination of equal channel angular pressing and rotary swaging (ECAP/RS). Tensile and fatigue tests were conducted, along with detailed microscopy and evaluation of corrosion resistance and biocompatibility. An average yield strength of 1383 MPa was obtained while maintaining moderate ductility of 10 %. This represents the highest strength ever recorded for cp-Ti, even exceeding that of Ti64. Additionally, fatigue endurance limit increased by 43 % up to 600 MPa, almost obtaining that of Ti64. Strengthening mechanisms were attributed to the ultrafine-grained (UFG) microstructure generated by ECAP/RS, along with strong crystallographic texture and formation of sub-grain structure. Furthermore, the corrosion resistance and biocompatibility of cp-Ti were largely unaffected, potentially easing regulatory transition in future medical devices. Thus, these results demonstrate high potential of combined ECAP/RS processing to manufacture UFG cp-Ti grade 4 materials that prospectively allow for the substitution of questionable alloys and downsizing of medical implants.

A case of complex asphyxia sheds light on problems in the classification of asphyxias.

Death from positional asphyxia is often an accidental event occurring when the victim's body assumes a position which can compromise an effective respiration. Its diagnosis is usually not simple, because it needs to know the exact circumstance in which the body was found and the original positioning of all the body segments. In this case, a 41-year-old man with a history of opioid drugs abuse was found dead in a knee-chest position; the head was down on the floor with the face resting on a plastic bag. Pictures of the scene of death was taken while the body was still in its original position. At first, the main suspicion was that of a fatal overdose. Following the autopsy examination, completed by histological and toxicological examinations, the cause of death was determined as postural asphyxia secondary to intoxication by methadone, in the presence of ischemic heart disease. Some features, moreover, were typical of the death in head down position, and the prolonged knee-chest position was also associated with the obstruction of mouth and nose by the plastic bag, which may have contributed to the asphyxiation. These cases of "combined" asphyxia represent a challenge for the current classifications of asphyxia, which are very variable and not standardized, as we observe from a brief review of the literature. The elaboration of new systems of classification for asphyxias, which must be clear, simple and shareable, is necessary to avoid confusion in categorizing cases that present overlapping between several types of asphyxiation modalities.

Microstructural Origins of the Corrosion Resistance of a Mg-Y-Nd-Zr Alloy Processed by Powder Bed Fusion - Laser Beam.

Magnesium alloys are biocompatible, biodegradable and have the ability to promote bone ingrowth, making them ideal candidate materials for replacing auto- and allografts in future treatments of large bone defects. Powder bed fusion-laser beam (PBF-LB) additive manufacturing of these alloys would further allow for the production of complex structures, optimized for bone grafting. However, the corrosion rates of structures processed by PBF-LB remain too high. An improved understanding of the influence of the microstructure generated during PBF-LB on the corrosion properties is considered key to their future implementation in implants. In this study, the effect of PBF-LB processing and subsequent hot isostatic pressing (HIP) on the microstructure and texture in different sample directions was studied and related to the corrosion behavior of a Mg-Y-Nd-Zr alloy. The results were compared with an extruded Mg-Y-Nd-Zr alloy. A higher amount of secondary phases resulted in a higher rate of localized corrosion for the PBF-LB processed material compared to that for the extruded one. Due to growth of the secondary phases, the corrosion rate was further increased after HIP. Moreover, a strong texture was observed in the PBF-LB material, and it was also enhanced in the HIP material. While this affected the electrochemical activity as measured by potentiodynamic polarization tests, any texture effect appeared to be masked by the contribution of the secondary phases in the longer-term mass change and hydrogen evolution tests. Future work should look further into the influence of individual process parameters on the microstructure and the resulting corrosion behavior of the material, to further clarify its interdependence.

Thoracic spinal cord herniation: case report and technical note.

Idiopathic spinal cord herniation and tethering through an anterior dural defect in the thoracic spine is an uncommon but increasingly recognized cause of Brown-Séquard syndrome. High-resolution magnetic resonance imaging is the method of choice to visualize anterior herniation of the spinal cord, although computed tomography myelography may still be performed. Idiopathic spinal cord herniation is a treatable cause of myelopathy. Notably, surgical treatment, consisting of reducing the herniation by closing the dural defect with the use of sutures, or enlarging the dural defect, has been recommended as the procedure of choice, but is difficult to perform in the small space in front of the spinal cord. When the dural defect is enlarged, recurrent transdural herniation may occur. We describe a new technique by wrapping a dura graft, biological glue and haemostatic around the spinal cord to prevent recurrent transdural herniation.