Systematic Review and Meta-Analysis on Colorectal Anastomotic Techniques.

Purpose: Anastomosis creation after resective gastrointestinal surgery is a crucial task. The present review examines the techniques and implants currently available for anastomosis creation and analyses to which extent they already address our clinical needs, with a special focus on their potential to enable further trauma minimization in visceral surgery. Methods: A multi-database research was conducted in MEDLINE, Scopus, and Cochrane Library. Comparative controlled and uncontrolled clinical trials dealing with anastomosis creation techniques in the intestinal tract in both German and English were included and statistically significant differences in postoperative complication incidences were assessed using the RevMan5.4 Review Manager (Cochrane Collaboration, Oxford, UK). Results: All methods and implant types were analyzed and compared with respect to four dimensions, assessing the techniques' current performances and further potentials for surgical trauma reduction. Postoperative outcome measures, such as leakage, stenosis, reoperation and mortality rates, as well as the tendency to cause bleeding, wound infections, abscesses, anastomotic hemorrhages, pulmonary embolisms, and fistulas were assessed, revealing the only statistically significant superiority of hand-suture over stapling anastomoses with respect to the occurrence of obstructions. Conclusion: Based on the overall complication rates, it is concluded that none of the anastomosis systems addresses the demands of operative trauma minimization sufficiently yet. Major problems are furthermore either low standardization potentials due to dependence on the surgeons' levels of experience, high force application requirements for the actual anastomosis creation, or large and rigid device designs interfering with flexibility demands and size restrictions of the body's natural access routes. There is still a need for innovative technologies, especially with regard to enabling incisionless interventions.

Design of a force-measuring setup for colorectal compression anastomosis and first ex-vivo results.

PURPOSE: The introduction of novel endoscopic instruments is essential to reduce trauma in visceral surgery. However, endoscopic device development is hampered by challenges in respecting the dimensional restrictions, due to the narrow access route, and by achieving adequate force transmission. As the overall goal of our research is the development of a patient adaptable, endoscopic anastomosis manipulator, biomechanical and size-related characterization of gastrointestinal organs are needed to determine technical requirements and thresholds to define functional design and load-compatible dimensioning of devices. METHODS: We built an experimental setup to measure colon tissue compression piercing forces. We tested 54 parameter sets, including variations of three tissue fixation configurations, three piercing body configurations (four, eight, twelve spikes) and insertion trajectories of constant velocities (5 mms-1, 10 mms-1,15 mms-1) and constant accelerations (5 mms-2, 10 mms-2, 15 mms-2) each in 5 samples. Furthermore, anatomical parameters (lumen diameter, tissue thickness) were recorded. RESULTS: There was no statistically significant difference in insertion forces neither between the trajectory groups, nor for variation of tissue fixation configurations. However, we observed a statistically significant increase in insertion forces for increasing number of spikes. The maximum mean peak forces for four, eight and twelve spikes were 6.4 ± 1.5 N, 13.6 ± 1.4 N and 21.7 ± 5.8 N, respectively. The 5th percentile of specimen lumen diameters and pierced tissue thickness were 24.1 mm and 2.8 mm, and the 95th percentiles 40.1 mm and 4.8 mm, respectively. CONCLUSION: The setup enabled reliable biomechanical characterization of colon material, on the base of which design specifications for an endoscopic anastomosis device were derived. The axial implant closure unit must enable axial force transmission of at least 28 N (22 ± 6 N). Implant and applicator diameters must cover a range between 24 and 40 mm, and the implant gap, compressing anastomosed tissue, between 2 and 5 mm.

Author Correction: A semi-automated virtual workflow solution for the design and production of intraoral molding plates using additive manufacturing: the first clinical results of a pilot-study.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Facilitating CAD/CAM nasoalveolar molding therapy with a novel click-in system for nasal stents ensuring a quick and user-friendly chairside nasal stent exchange.

Nasoalveolar molding (NAM) aims to improve nasal symmetry with a nasal stent in cleft lip and palate (CLP) patients. When plates have to be exchanged because of dentoalveolar growth or cleft reduction, the nasal stent has to be mounted onto a new plate. This procedure elongates visiting hours for patients and parents or requires second treatment sessions. This study introduces a quick-lock additive manufacturing solution for chairside nasal stent exchange called RapidNAM. A novel taping retention pin has been designed that enables nasal stent insertion. Patients with unilateral CLP were included in this study. Plaster models were digitalized and measured by two independent observers. Two methods of CAD/CAM-molding therapies were compared: (i) conventional adhesion of a nasal stent (CAD/CAM NAM); (ii) quick-lock system in which the nasal stent was transferred to another plate (RapidNAM). CAD/CAM NAM and its refinement RapidNAM significantly increased the cleft-side nasal height and tilted the nose towards symmetry. The quick-lock system minimizes wire adaptations, since the pre-existing stent can be reused. The new nasal stent development seems a feasible solution to minimize visiting hours but with clinically satisfactory results. This new nasal stent system combines traditional elements of NAM with CAD/CAM-technology.

A semi-automated virtual workflow solution for the design and production of intraoral molding plates using additive manufacturing: the first clinical results of a pilot-study.

Computer-aided design and computer-aided manufacturing (CAD/CAM) technology has been implemented in the treatment of cleft lip and palates (CLP) by several research groups. This pilot study presents a technique that combines intraoral molding with a semi-automated plate generation and 3D-printing. The clinical results of two intraoral molding approaches are compared. This is the first clinical investigation of semi-automated intraoral molding. Our study included newborns with unilateral CLP. Plaster models were digitalized and measured by two independent observers. Two methods of CAD/CAM-assisted intraoral molding were compared: (i) stepwise manual design of molding plates (conventional CAD/CAM-intraoral molding) and (ii) a semi-automated approach with an automated detection of alveolar ridges (called RapidNAM) assisted by a graphical user interface (GUI). Both approaches significantly narrowed the clefts and resulted in a harmonic alveolar crest alignment. The GUI was easy to use and generated intraoral molding devices within minutes. The presented design solution is an efficient technical refinement with good clinical results. The semi-automated plate generation with a feasible GUI is fast but allows individual adaptations. This promising technique might facilitate and foster the more widespread use of CAD/CAM-technology in intraoral molding therapy.

Development and evaluation of a spray applicator for platelet-rich plasma.

Autologous platelet-rich blood derivatives are used in a variety of medical fields in which the enhancement of wound healing by applying growth factors released from platelets is an especially promising application. Treatment of the whole surface of large-area wounds with a small volume of blood derivatives is best achieved by spraying. In this study, we present a compact and self-contained spraying device without external connections such as a power supply or compressor. The biocompatible propellant R134a is used to aspirate and atomize the blood derivatives. A 3D-printed, two-substance nozzle functions as the operating unit, throttle, mixing zone and atomization unit. The spray characteristics were evaluated via experimental flow volume, cone and droplet size measurements. Biological evaluation was performed by flow cytometry comparing platelet activation in the blood derivatives before and after spraying, and PDGF ELISA comparing growth factor release, respectively. Homogeneity and morphology of the sprayed blood cells were evaluated with scanning electron microscopy. The results show that the developed spraying device has excellent spray characteristics with low mechanical impact on the cellular components of the blood derivatives. Our spraying device is a promising tool for applying evenly distributed platelet-rich blood derivatives to treatment sites.

Additive-manufactured microporous polymer membranes for biomedical in vitro applications.

Microscale porous membranes are used in a wide range of technical and medical applications such as water treatment, dialysis and in vitro test systems. A promising approach to control membrane properties and overcome limitations of conventional fabrication techniques is given by additive manufacturing (AM). In this study, we designed and printed a microporous membrane via digital light processing and validated its use for biomedical in vitro applications based on the example of a cell culture insert. A multi-layer technique was developed, resulting in an eight-layer membrane with an average pore diameter of 25 µm. Image analyses proved the printing accuracy to be high with small deviations for an increasing number of layers. Permeability tests with brilliant blue FCF (E133, triarylmethane dye) and growth factors comparing the printed to track-etched membranes showed similar transfer dynamics and confirmed sufficient separation properties. Overall, the results showed that printing microporous polymer membranes is possible and highlight the potential of AM for biomedical in vitro applications such as cell culture inserts, scaffolds for tissue engineering or bioreactors.

A prospective longitudinal study of postnatal dentoalveolar and palatal growth: The anatomical basis for CAD/CAM-assisted production of cleft-lip-palate feeding plates.

This study describes the dentoalveolar and palatal growth during the first months of life. Knowledge concerning this development is essential to avoid unwanted events such as mucosal ulcerations or restriction of growth when cleft-lip and palate (CLP) patients are treated. The results involve the generation of CAD/CAM CLP-feeding plates. Intraoral impressions from 32 healthy newborns were taken monthly for 5 months, supplemented by measurements of body weight, length, and occipital-frontal head circumference. The casts were digitalized, and two observers manually selected defined anatomical landmarks on virtual 3-D models. The distances between these landmarks were evaluted. Statistical analysis included an inter-rater agreement analysis and the determination of growth. In total, 213 casts were analyzed, with 65 models excluded because of inaccuracies in impression-taking or cast production. Overall longitudinal growth was 20.3%, whereas transversal growth reached a maximum of 21.1%. Vertical growth was 32.4% at the tuberal level. On the basis of these results, a semiautomated series of feeding plates allowing for monthly expansion could be generated. The acquired data serve as a useful reference for other pediatric and orthofacial investigations and treatments. One such application is the automated, fully virtual manufacture of CLP-feeding plates based on only one impression-taking. Our data reveal when caution is needed to prevent ulceration. The series of plates generated can minimize the time-consuming impression-taking and the production of further plaster models. The method of measurement is suitable for documentary purposes. Clin. Anat. 30:846-854, 2017. © 2017 Wiley Periodicals, Inc.

RapidNAM: generative manufacturing approach of nasoalveolar molding devices for presurgical cleft lip and palate treatment.

Nasoalveolar molding (NAM) is an accepted treatment strategy in presurgical cleft therapy. The major drawbacks of the treatment listed in the literature relate to the time of the treatment and the coordination of the required interdisciplinary team of therapists, parents, and patients. To overcome these limitations, we present the automated RapidNAM concept that facilitates the design and manufacturing process of NAM devices, and that allows the virtual modification and subsequent manufacture of the devices in advance, with a growth prediction factor adapted to the patient's natural growth. The RapidNAM concept involves (i) the prediction of three trajectories that envelope the fragmented alveolar segments with the goal to mimic a harmonic arch, (ii) the extrusion from the larger toward the smaller alveolar segment along the envelope curves toward the harmonic upper alveolar arch, and (iii) the generation of the NAM device with a ventilation hole, fixation pin, and fixation points for the nasal stents. A feasibility study for a vector-based approach was successfully conducted for unilateral and bilateral cleft lip and palate (CLP) patients. A comparison of the modified target models with the reference target models showed similar results. For further improvement, the number of landmarks used to modify the models was increased by a curve-based approach.

C-arm angle measurement with accelerometer for brachytherapy: an accuracy study.

PURPOSE: X-ray fluoroscopy guidance is frequently used in medical interventions. Image-guided interventional procedures that employ localization for registration require accurate information about the C-arm's rotation angle that provides the data externally in real time. Optical, electromagnetic, and image-based pose tracking systems have limited convenience and accuracy. An alternative method to recover C-arm orientation was developed using an accelerometer as tilt sensor. METHODS: The fluoroscopic C-arm's orientation was estimated using a tri-axial acceleration sensor mounted on the X-ray detector as a tilt sensor. When the C-arm is stationary, the measured acceleration direction corresponds to the gravitational force direction. The accelerometer was calibrated with respect to the C-arm's rotation along its two axes, using a high-accuracy optical tracker as a reference. The scaling and offset error of the sensor was compensated using polynomial fitting. The system was evaluated on a GE OEC 9800 C-arm. Results obtained by accelerometer, built-in sensor, and image-based tracking were compared, using optical tracking as ground truth data. RESULTS: The accelerometer-based orientation measurement error for primary angle rotation was -0.1 ± 0.0° and for secondary angle rotation it was 0.1 ± 0.0°. The built-in sensor orientation measurement error for primary angle rotation was -0.1 ± 0.2°, and for secondary angle rotation it was 0.1 ± 0.2°. The image-based orientation measurement error for primary angle rotation was -0.1 ± 1.3°, and for secondary angle rotation it was -1.3 ± 0.3°. CONCLUSION: The accelerometer provided better results than the built-in sensor and image-based tracking. The accelerometer sensor is small, inexpensive, covers the full rotation range of the C-arm, does not require line of sight, and can be easily installed to any mobile X-ray machine. Therefore, accelerometer tilt sensing is a very promising applicant for orientation angle tracking of C-arm fluoroscopes.

A new web-based method for automated analysis of muscle histology.

BACKGROUND: Duchenne muscular dystrophy is an inherited degenerative neuromuscular disease characterised by rapidly progressive muscle weakness. Currently, curative treatment is not available. Approaches for new treatments that improve muscle strength and quality of life depend on preclinical testing in animal models. The mdx mouse model is the most frequently used animal model for preclinical studies in muscular dystrophy research. Standardised pathology-relevant parameters of dystrophic muscle in mdx mice for histological analysis have been developed in international, collaborative efforts, but automation has not been accessible to most research groups. A standardised and mainly automated quantitative assessment of histopathological parameters in the mdx mouse model is desirable to allow an objective comparison between laboratories. METHODS: Immunological and histochemical reactions were used to obtain a double staining for fast and slow myosin. Additionally, fluorescence staining of the myofibre membranes allows defining the minimal Feret's diameter. The staining of myonuclei with the fluorescence dye bisbenzimide H was utilised to identify nuclei located internally within myofibres. Relevant structures were extracted from the image as single objects and assigned to different object classes using web-based image analysis (MyoScan). Quantitative and morphometric data were analysed, e.g. the number of nuclei per fibre and minimal Feret's diameter in 6 month old wild-type C57BL/10 mice and mdx mice. RESULTS: In the current version of the module "MyoScan", essential parameters for histologic analysis of muscle sections were implemented including the minimal Feret's diameter of the myofibres and the automated calculation of the percentage of internally nucleated myofibres. Morphometric data obtained in the present study were in good agreement with previously reported data in the literature and with data obtained from manual analysis. CONCLUSIONS: A standardised and mainly automated quantitative assessment of histopathological parameters in the mdx mouse model is now available. Automated analysis of histological parameters is more rapid and less time-consuming. Moreover, results are unbiased and more reliable. Efficacy of therapeutic interventions, e.g. within the scope of a drug screening or therapeutic exon skipping, can be monitored. The automatic analysis system MyoScan used in this study is not limited exclusively to dystrophin-deficient mice but also represents a useful tool for applications in the research of other dystrophic pathologies, various other skeletal muscle diseases and degenerative neuromuscular disorders.

Mechanical properties and in vitro behavior of nanofiber-hydrogel composites for tissue engineering applications.

Hydrogel-based biomaterial systems have great potential for tissue reconstruction by serving as temporary scaffolds and cell delivery vehicles for tissue engineering (TE). Hydrogels have poor mechanical properties and their rapid degradation limits the development and application of hydrogels in TE. In this study, nanofiber reinforced composite hydrogels were fabricated by incorporating electrospun poly(ε-caprolactone) (PCL)/gelatin 'blend' or 'coaxial' nanofibers into gelatin hydrogels. The morphological, mechanical, swelling and biodegradation properties of the nanocomposite hydrogels were evaluated and the results indicated that the moduli and compressive strengths of the nanofiber reinforced hydrogels were remarkably higher than those of pure gelatin hydrogels. By increasing the amount of incorporated nanofibers into the hydrogel, the Young's modulus of the composite hydrogels increased from 3.29 ± 1.02 kPa to 20.30 ± 1.79 kPa, while the strain at break decreased from 66.0 ± 1.1% to 52.0 ± 3.0%. Compared to composite hydrogels with coaxial nanofibers, those with blend nanofibers showed higher compressive strength and strain at break, but with lower modulus and energy dissipation properties. Biocompatibility evaluations of the nanofiber reinforced hydrogels were carried out using bone marrow mesenchymal stem cells (BM-MSCs) by cell proliferation assay and immunostaining analysis. The nanocomposite hydrogel with 25 mg ml(-1) PCL/gelatin 'blend' nanofibers (PGB25) was found to enhance cell proliferation, indicating that the 'nanocomposite hydrogels' might provide the necessary mechanical support and could be promising cell delivery systems for tissue regeneration.

A novel pulsatile bioreactor for mechanical stimulation of tissue engineered cardiac constructs.

After myocardial infarction, the implantation of stem cell seeded scaffolds on the ischemic zone represents a promising strategy for restoration of heart function. However, mechanical integrity and functionality of tissue engineered constructs need to be determined prior to implantation. Therefore, in this study a novel pulsatile bioreactor mimicking the myocardial contraction was developed to analyze the behavior of mesenchymal stem cells derived from umbilical cord tissue (UCMSC) colonized on titanium-coated polytetrafluorethylene scaffolds to friction stress. The design of the bioreactor enables a simple handling and defined mechanical forces on three seeded scaffolds at physiological conditions. The compact system made of acrylic glass, Teflon®, silicone, and stainless steel allows the comparison of different media, cells and scaffolds. The bioreactor can be gas sterilized and actuated in a standard incubator. Macroscopic observations and pressure-measurements showed a uniformly sinusoidal pulsation, indicating that the bioreactor performed well. Preliminary experiments to determine the adherence rate and morphology of UCMSC after mechanical loadings showed an almost confluent cellular coating without damage on the cell surface. In summary, the bioreactor is an adequate tool for the mechanical stress of seeded scaffolds and offers dynamic stimuli for pre-conditioning of cardiac tissue engineered constructs in vitro.

Comparative analysis of adherence, viability, proliferation and morphology of umbilical cord tissue-derived mesenchymal stem cells seeded on different titanium-coated expanded polytetrafluoroethylene scaffolds.

Umbilical cord tissue comprises an attractive new source for mesenchymal stem cells. Umbilical cord tissue-derived mesenchymal stem cells (UCMSC) exhibit self-renewal, multipotency and immunological naivity, and they can be obtained without medical intervention. The transfer of UCMSC to the ischemic region of the heart may have a favorable impact on tissue regeneration. Benefit from typical cell delivery by injection to the infarcted area is often limited due to poor cell retention and survival. Another route of administration is to use populated scaffolds implanted into the infarcted zone. In this paper, the seeding efficiency of UCMSC on uncoated and titanium-coated expanded polytetrafluoroethylene (ePTFE) scaffolds with different surface structures was determined. Dualmesh (DM) offers a corduroy-like surface in contrast to the comparatively planar surface of cardiovascular patch (CVP). The investigation of adherence, viability and proliferation of UCMSC demonstrates that titanium-coated scaffolds are superior to uncoated scaffolds, independent of the surface structure. Microscopic images reveal spherical UCMSC seeded on uncoated scaffolds. In contrast, UCMSC on titanium-coated scaffolds display their characteristic spindle-shaped morphology and a homogeneous coverage of CVP. In summary, titanium coating of clinically approved CVP enhances the retention of UCMSC and thus offers a potential cell delivery system for the repair of the damaged myocardium.

Search for optimized conditions for sealing and storage of bypass vessels: influence of preservation solution and filling pressure on the degree of endothelialization.

The aim of the present study was to develop methods for the rapid assessment of intimal quality of coronary bypass segments of venous origin, and to prevent endothelial damage by improved intraoperative handling of graft segments. Particular attention was paid to the influence of the composition of the preservation solution and the intravasal filling pressure on the degree of endothelialization. Intrava-sal exposure to Alcian blue at pH<3 resulted in highly specific staining of intimal regions with functionally or structurally damaged endothelium. Standardization of preparation, staining and image acquisition of the intimal surface of graft remnants and subsequent computer-aided planimetry of these images made it possible for the first time to perform rapid serial investigations for quality control of bypass grafts. Using saline as the rinsing and intraoperative storage medium resulted in the loss of more than 50% of the endothelium at intravasal pressures of 0-100 mmHg. Increasing the pressure resulted eventually in complete de-endothelialization. In contrast, grafts incubated in a customized plasma derivative tolerated pressures of up to 200 mmHg with no significant endothelial loss; and even after exposure to 1,000 mmHg (10 times the average mean arterial pressure!) more than 70% of the endothelium were intact and vital. These findings imply strongly that the quality of aortocoronary bypass grafts of venous origin can be improved substantially by the use of a plasma derivative solution for intraoperative preservation and by monitoring and controlling the intravasal pressures reached during sealing and storage.

Contribution of outgrowth endothelial cells from human peripheral blood on in vivo vascularization of bone tissue engineered constructs based on starch polycaprolactone scaffolds.

In the present study we assessed the potential of human outgrowth endothelial cells (OEC), a subpopulation within endothelial progenitor cell cultures, to support the vascularization of a complex tissue engineered construct for bone. OEC cultured on starch polycaprolactone fiber meshes (SPCL) in monoculture retained their endothelial functionality and responded to angiogenic stimulation by VEGF (vascular endothelial growth factor) in fibrin gel-assays in vitro. Co-culture of OEC with human primary osteoblasts (pOB) on SPCL, induced an angiogenic activation of OEC towards microvessel-like structures achieved without additional supplementation with angiogenic growth factors. Effects of co-cultures with pOB on the vascularization process by OEC in vivo were tested by subcutaneous implantation of Matrigel plugs containing both, OEC and pOB, and resulted in OEC-derived blood vessels integrated into the host tissue and anastomosed to the vascular supply. In addition, morphometric analysis of the vascularization process by OEC indicated a better performance of OEC in the co-cultures with primary osteoblasts compared to monocultures of OEC. The contribution of OEC to vascular structures and the beneficial effect of the co-culture with primary human osteoblasts on the vascularization in vivo was additionally proven by subcutaneous implantation of pre-cellularized and pre-cultured SPCL constructs. OEC contributed to the vascular structures, by generating autogenic vessels or by incorporation into chimeric vessels consisting of both, human and mouse endothelial cells. The current data highlight the vasculogenic potential of OEC for bone tissue engineering applications and indicate a beneficial influence of constructs including both osteoblasts and endothelial cells for vascularization strategies.

Matrix metalloproteinases, tissue inhibitors of metalloproteinases, aminoterminal propeptide of procollagen type III, and hyaluronan in sera and tissue of patients with capsular contracture after augmentation with Trilucent breast implants.

In various fibrotic diseases, matrix metalloproteinases (MMPs) and their natural inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), play an important role. In our study, serum concentrations of MMP-1, MMP-2, MMP-9, TIMP-1, and TIMP-2 were determined by enzyme-linked immunosorbent assay in 17 female patients with Baker grade II (n =9), III (n =7), and IV (n =1) capsular contracture after bilateral cosmetic mamma augmentation with Trilucent implants (AEI, Inc., Caversham, United Kingdom). Samples of capsular tissue for standard histology and immunohistochemistry were obtained from all patients. Sera from 20 female patients who had plastic surgery for reduction mammaplasty were used as the control group. The aminoterminal propeptide of procollagen type III (PIIINP) and hyaluronan were analyzed as markers for fibrogenesis in both groups, too. Statistical analysis was performed using the Mann-Whitney test and Spearman rank correlation. Patients with capsular contracture presented significantly higher concentrations of TIMP-1 and TIMP-2 in their sera than did the control group (p < 0.05), which correlated with Baker grade (r = 0.7 versus r = 0.65; p < 0.05). The concentration of MMP-2 was significantly higher in the sera of patients with capsule fibrosis, whereas there were no significant differences in MMP-1, MMP-9, and PIIINP serum concentrations. Patients with capsule fibrosis had a significantly lower MMP-to-TIMP ratio (1.1 +/- 0.4, p <0.05) than the control group (1.5 +/- 0.4), which correlated with the Baker classification (r =0.7; p <0.05). The hyaluronan serum concentration of patients with capsular contracture was significantly higher (p < 0.05) and correlated with the Baker grade (r = 0.73; p < 0.05), whereas PIIINP showed no difference. In the histologic evaluation, there was a chronic inflammatory reaction in the capsules around the breast implants and refracting material within the substance. Immunohistochemically, TIMP-1 and TIMP-2 showed an intensive accumulation, and MMP-2 showed a local reaction. PIIINP could be detected, too, whereas there was no staining for MMP-1 and MMP-9. The elevated systemic MMP-2 concentration and the local positive staining in the tissue might be due to the chronic inflammatory reaction. Nevertheless, the balance between MMPs and their natural inhibitors is disturbed in patients with capsule contracture. The elevated systemic concentration of TIMPs might be a pathway in the pathogenesis of severe fibrosis after breast augmentation with alloplastic material. Hyaluronan might be a useful marker for early prediction of capsule fibrosis, whereas PIIINP is not useful as a predictor.