The application of near‐infrared spectroscopy for the process control of biogas plants was evaluated in this study. The study involves the generation of first calibrations using two instruments, a commercial Fourier transform near‐infrared instrument and a grating spectrometer‐based prototype. Both the current state of the prototype hardware and the methodology were examined. A biogas plant was sampled regularly during a time period of 43 wk. Classic analysis methods as well as spectroscopic methods were used for the examination of the samples. Calibrations for dry‐matter content and content of organic dry matter were developed for both devices using the partial least squares regression after preprocessing the spectra. It was evident that the application of near‐infrared spectroscopy using simplified and robust hardware on‐site of biogas plants is possible. It is feasible to find high deviations from the aspired consistence of the fermentation medium and some substrates with the presented calibrations.

Osteoarthritis of the hip joint (coxarthrosis) is the most common hip disease in adults. Since the 1960s, total hip arthroplasty (THA) has made great progress and is nowadays one of the most frequently used procedures in orthopedic surgery. Different bearing concepts exist in various implant designs. A metal-on-metal bearing can create metal debris and lead to metallosis. We present a unique case of a 78-year old woman, who received hip resurfacing with a McMinn-like prosthesis 15 years ago. Over the cause of time, metallosis developed and created a bone cyst in the Os ilium, and osteolysis led to a dislocation of the femoral implant. A minor stumble fall led to a fracture of the Os ilium. We present our treatment method with implantation of a cemented THA and refill of the bone cyst with bone from allogene femoral heads. The surgery led to a reconstruction of the physiological center of rotation in the hip. Consequently, to the inpatient stay, the patient took part in a follow-up treatment with intensive physiotherapy. Taken together, the results after total hip arthroplasty are more superior to other hip surface replacements in terms of longevity and patient satisfaction. Especially, metal-on-metal bearing couples carry a great risk of metallosis, which goes a long with pseudotumors, osteolysis, and the elevated metal ions in the blood. Since this case is unique in the literature, no guidelines are noted for surgical treatment. In our opinion, a periprosthetic fracture of this type should be performed in a hospital using extensive endoprosthetic expertise.

Background and Purpose:Two-stage revision arthroplasty is a common technique for the treatment of infected total knee replacement. Few reports have addressed the conversion of a fused knee into a total knee replacement. However, there is no case reported of converting an infected fused knee into a hinge knee using a one-stage procedure.Methods:We report on a 51-year old male patient with an infected fused knee after multiple surgeries.Results and Interpretation:A one-stage conversion of septic fused knee into total knee arthroplasty by a rotational hinge prosthesis was performed. The case highlights that with profound preoperative assessment, meticulous surgical technique, combined antibiotic treatment and the right implant, one-stage revision in a surgical challenge may have a role as a treatment option with good functional outcome.

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