Our results corroborate the assumption that skin barrier dysfunction plays an essential role in the pathogenesis of CHE.

P atients known to develop allergic reactions to nickel (Ni), cobalt (Co), or chromium (Cr) often develop eczema in association with items of daily use such as jewelry, earrings, or watchbands. The overall sensitization rates to these metals may range between 1.1% (chromium) and 13% (nickel) in the general population, with further differences based on age and sex 1 . Chromium-cobalt alloys and stainless steel are widely used as orthopaedic implants and may release nickel, chromium, or cobalt into the surrounding tissues as a consequence of either wear or corrosion 2 . Some patients with a metal allergy may develop dermatitis in association with orthopaedic implants, and the prevalence of dermal sensitivity in patients with a joint replacement, particularly a failed implant, is higher than that in the general population 3 . Metal sensitivity rates to nickel, cobalt, or chromium may be as high as 43% in orthopaedic patients with wellfunctioning implants and as high as 71% in patients with poorly functioning implants 3 . In contrast, because of their excellent biocompatibility, titanium (Ti)-based materials are not considered to provoke allergic reactions. Our patient developed eczema and impaired wound-healing following the fixation of an ankle fracture with titanium-based implants. Histological analysis of the tissue around the implant demonstrated inflammation primarily with lymphocytes, and a contact allergy to nickel and cobalt was found in the absence of titanium hyperreactivity, raising the question of a prior unknown nickel exposure as the source of the complications. The patient was informed that data concerning this case would be submitted for publication, and she consented. Case ReportA fifty-nine-year-old woman with a trimalleolar ankle fracture with rupture of the syndesmosis (Fig. 1) underwent Fig. 1

In Laser powder bed fusion (L-PBF), metal powders, sensitive to humidity and oxygen, like AlSi10Mg or Ti-6Al-4 V are used as starting material. Titanium-based materials are influenced by oxygen and nitrogen due to the formation of oxides and nitrides, respectively. During this research, the oxygen concentration in the build chamber was controlled from 2 ppm to 1000 ppm using an external measurement device. Built Ti-6Al-4 V specimens were evaluated regarding their microstructure, hardness, tensile strength, notch toughness, chemical composition and porosity, demonstrating the importance of a stable atmospheric control. It could be shown that an increased oxygen concentration in the shielding gas atmosphere leads to an increase of the ultimate tensile strength by 30 MPa and an increased (188.3 ppm) oxygen concentration in the bulk material. These results were compared to hot isostatic pressed (HIPed) samples to prevent the influence of porosity. In addition, the fatigue behavior was investigated, revealing increasingly resistant samples when oxygen levels in the atmosphere are lower.

No abstract