Kurt Schicho

Extracorporeal shock wave therapy (ESWT) is a well-known biophysical therapy that offers several beneficial effects, including a presumed increase in the growth of blood vessels. The chorioallantoic membrane (CAM) assay is a well-established in vivo model for studying angiogenesis. The aim of this study was to develop an experimental setup to apply ESWT to CAM in a three-step process and investigate the vascular response. First, we conducted virtual simulations of various shock-wave application setups to CAM and subsequently tested them in preliminary studies to evaluate their feasibility. In the final stage, we employed the most suitable protocol to investigate the angiogenic effects of shock wave therapy in practical applications. Our findings suggest that ESWT increases the number of vessels in CAM. In the final biological experiment (n = 16 CAM per group), ESWT increased vessel number by approximately 14.3% (p = 0.050) and branching points by approximately 13.5% (p = 0.070), while mean vessel thickness decreased by approximately 8.0% (p = 0.047); total vascular area per image remained unchanged (p = 0.760). These effects were concentrated in short-to-medium, thinner-caliber vessels rather than reflecting a uniform increase in vascularity, consistent with the emergence of a denser microvascular network. This new experimental setup paves the way for future research into the angiogenic effects of ESWT and provides a multifaceted model as an intermediate step between in vitro mechanistic studies and clinical translation.

Angiogenesis is a highly regulated process. It promotes tissue regeneration and contributes to tumor growth. Existing therapeutic concepts interfere with different steps of angiogenesis. The quantification of the vasculature is of crucial importance for research on angiogenetic effects. The chorioallantoic membrane (CAM) assay is widely used in the study of angiogenesis. Ex ovo cultured chick embryos develop an easily accessible, highly vascularised membrane on the surface. Tumor xenografts can be incubated on this membrane enabling studies on cancer angiogenesis and other major hallmarks. However, there is no commonly accepted gold standard for the quantification of the vasculature of the CAM. We compared four widely used measurement techniques to identify the most appropriate one for the quantification of the vascular network of the CAM. The comparison of the different quantification methods suggested that the CAM assay application on the IKOSA platform is the most suitable image analysis application for the vasculature of the CAM. The new CAM application on the IKOSA platform turned out to be a reliable and feasible tool for practical use in angiogenesis research. This novel image analysis software enables a deeper exploration of various aspects of angiogenesis and might support future research on new anti-angiogenic strategies for cancer treatment.

The application of light in various therapeutic settings known as Photobiomodulation (PBM) is well established. Indications are the improvement of wound healing and tissue regeneration, scarring, and perfusion as well as pain therapy. Tissue perfusion is mandatory for successful wound healing. Nevertheless, there is a lack of mechanistic studies. We investigate the potential effect of PBM from light emitting diodes (LED) at 635 nm, 80 mW/cm², 24 J/cm² on angiogenesis in a two-part study: 1.) Investigation of the effect of PBM on the proliferation of endothelial cells and on vasculogenesis in a co-culture model of endothelial cells and stem cells. 2.) Investigation of the influence of PBM at chick egg chorioallantoic membrane (CAM) assays with fresh human skin xenografts. In both study phases, we observed a stimulating effect of PBM at 635 nm; in part 1: for proliferation of HUVEC (human umbilical vein endothelial cells) (25833 ± 12859 versus 63002 ± 35760 cells/well, p < 0.05, for cellular network formation (2.1 ± 2.1 versus 4.6 ± 3.5, p < 0.05) and for less cell compactness p = 0.01; in part 2: for the increase of number of vessel junctions per ROI (region of interest) (15.9 ± 2.6 versus 20.8 ± 5.4, p < 0.05). Our results suggest significant promotion of angiogenesis by PBM at 635 nm in vitro and in vivo.

In the past years, various applications of telemedicine have been found. Especially teleconsulting or telementoring has been accepted as a possible answer to upcoming higher quality demands utilizing expert knowledge in everyday clinical routine. In this work we investigate whether video transmission based on universal mobile telecommunication system (UMTS) by means of arthroscopic videos is clinically reasonable. Secondly, we examine the quality of the enabling technology especially for consolidated diagnostics and telementoring. Twenty arthroscopic video streams with a length of 60 s of each sequence, showing endoscopic craniomaxillofacial interventions such as arthroscopies of the temoporomandibular joint or endoscopic assisted open reductions of mandibular head fractures, were hosted on a server and analyzed on a UMTS cellphone. Each of the arthroscopic video sequences was independently evaluated by two consultants and a medical expert in TMJ surgery. Quality aspects such as identifiability of anatomical details, instruments, and tasks, and pathology were assessed in a questionnaire. Stability of transmission and breakdowns were also registered. The median percentage of completely transmitted videos without interruption was 85 ± 12.5% (interquartile range, IQR). In 6.7% of all video transmissions, complete interruption resulted, requiring restart. Of anatomical structures, 60.7% were correctly identified, while in 39.3% an identification error was detected. Tasks and instruments were recognized in 92.4%. In 94.8%, pathologies could be correctly diagnosed. The need for teleconsultation is given, since orientation in arthroscopy is difficult. UMTS-streamed endoscopic videos still have certain limitations regarding teleconsulting due to instability and delay. Nevertheless, the technology may currently be beneficial for teleteaching and could be used in the future in teleconsultation. Without affecting ongoing surgeries and with no special need for a lecture theater, this technology provides tele-education using standard hospital infrastructure.

Setting up a reliable and accurate reference coordinate system is a crucial part in computer assisted navigated surgery. As the use of splints is a well established technique for this purpose and any change in its geometry directly influences the accuracy of the navigation, a regular monitoring of such deformations should occur as a means of quality control. This work presents a method to quantify such deformations based on computed tomography images of a splint equipped with fiducial markers. Point-to-point registration is used to match the two data sets and some markers near to the navigation field are used to estimate the registration error. The Hausdorff Distance, describing the maximum of all minimal distances between two point sets in general, is applied to the surfaces of the models, being a measure for the overall change in geometry. Finally this method for quantification is demonstrated using a computed tomography data set of such a splint together with an artificially modified one, being an initial step to a study examining the influence of the Sterrad sterilisation system on acrylic splints.

Selected workflows combining computer-assisted teleplanning and navigation (including 3D-stereolithography) are presented. It is shown how interactive teleplanning of dental implants or optimization of a surgical treatment of large bone defects is done.

The aim of this prospective randomized study was to compare the clinical accuracy of and surgical time required for mandibular dental implant placement with 2 computer-assisted navigation systems using pre- and postoperative computerized tomographic (CT) data. In 16 patients with edentulous mandibles, 4 interforaminal implants per patient were placed with computer-assisted navigation. The implant bed was prepared by transmucosal drilling without mucosal punching. Patients were randomly allocated to either the VISIT navigation system (32 implants; 8 patients) or the Medtronic StealthStation Treon navigation system (32 implants; 8 patients). Pre- and postoperative CT scans were matched using the normalized mutual information 3D registration algorithm to compare preplanned and final implant positions. Operation room time was recorded from start of preoperative preparations to end of surgery. All implants were placed as planned; there were no intra- or postoperative complications. Average implant deviation errors of 0.7 mm and 0.9 mm were recorded for the VISIT and StealthStation Treon navigation systems, respectively. Timing revealed an average operation room time of 81.3 +/- 15.8 minutes for the VISIT navigation system and 60 +/- 10.4 minutes for the StealthStation Treon navigation system. The accuracy of implant bed preparation and placement was similar in both systems. Both navigation systems are equally precise in a clinical environment. However, total operation room time was 25% shorter with the StealthStation Treon navigation system, probably because of the faster tracking system update rate.