A crucial factor in tissue engineering of heart valves is the functional and physiologic scaffold design. In our current experiment, we describe a new fabrication technique for heart valve scaffolds, derived from x-ray computed tomography data linked to the rapid prototyping technique of stereolithography. To recreate the complex anatomic structure of a human pulmonary and aortic homograft, we have used stereolithographic models derived from x-ray computed tomography and specific software (CP, Aachen, Germany). These stereolithographic models were used to generate biocompatible and biodegradable heart valve scaffolds by a thermal processing technique. The scaffold forming polymer was a thermoplastic elastomer, a poly-4-hydroxybutyrate (P4HB) and a polyhydroxyoctanoate (PHOH) (Tepha, Inc., Cambridge, MA). We fabricated one human aortic root scaffold and one pulmonary heart valve scaffold. Analysis of the heart valve included functional testing in a pulsatile bioreactor under subphysiological and supraphysiological flow and pressure conditions. Using stereolithography, we were able to fabricate plastic models with accurate anatomy of a human valvular homograft. Moreover, we fabricated heart valve scaffolds with a physiologic valve design, which included the sinus of Valsalva, and that resembled our reconstructed aortic root and pulmonary valve. One advantage of P4HB and PHOH was the ability to mold a complete trileaflet heart valve scaffold from a stereolithographic model without the need for suturing. The heart valves were tested in a pulsatile bioreactor, and it was noted that the leaflets opened and closed synchronously under subphysiological and supraphysiological flow conditions. Our preliminary results suggest that the reproduction of complex anatomic structures by rapid prototyping techniques may be useful to fabricate custom made polymeric scaffolds for the tissue engineering of heart valves.

In this paper the first active surgical robot system (OTTO) in a clinical environment for maxillofacial surgery is presented. The medical application is described from a technical point of view and the requirements for a robot in this specialty are defined. The paper describes the system architecture of the robotics environment and the need for research and development. The robot's hardware is based o n a delta-kinematics robot system. At the current state of development, the robot can be used for inserting non-flexible catheters and for i mplanting bone fixtures in the skull.

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IntroductionAn increasing number of studies investigate the influence of training interventions on muscle thickness (MT) by using ultrasonography. Ultrasonography is stated as a reliable and valid tool to examine muscle morphology. Researches investigating the effects of a training intervention lasting a few weeks need a very precise measurement since increases in MT can be assumed as small. Therefore, the aim of the present work was to investigate the concordance between MT via sonography and muscle cross-sectional area (MCSA) determined via MRI imaging (gold standard) in the calf muscle.MethodsReliability of sonography measurement and the concordance correlation coefficient, the mean error (ME), mean absolute error (MAE) and the mean absolute percentage error (MAPE) between sonography and MRI were determined.ResultsResults show intraclass correlation coefficients (ICC) of 0.88–0.95 and MAPE of 4.63–8.57%. Concordance between MT and MCSA was examined showing ρ = 0.69–0.75 for the medial head and 0.39–0.51 c for the lateral head of the gastrocnemius. A MAPE of 15.88–19.94% between measurements were determined. Based on this, assuming small increases in MT due to training interventions, even with an ICC of 0.95, MAPE shows a high error between two investigators and therefore limited objectivity.DiscussionThe high MAPE of 15.88–19.94% as well as CCC of ρc = 0.39–0.75 exhibit that there are significant differences between MRI and sonography. Therefore, data from short term interventions using sonography to detect changes in the MT should be handled with caution.