The precise location of gastric and colorectal tumors is of paramount importance for the oncological surgeon as it dictates the limits of resection and the extent of lymphadenectomy. However, this task proves sometimes to be very challenging, especially in the laparoscopic setting when the tumors are small, have a soft texture, and do not invade the serosa. In this view, our research team has developed a new instrument adapted to minimally-invasive surgery, and manipulated solely by the operating surgeon which has the potential to locate precisely tumors of the digestive tract. It consists of an inductive proximity sensor and an electronic block encapsulated into an autoclavable stainless-steel cage that works in tandem with an endoscopic hemostatic clip whose structure was modified to increase detectability. By scanning the serosal side of the colon or stomach, the instrument is capable to accurately pinpoint the location of the clip placed previously during diagnostic endoscopy on the normal bowel mucosa, adjacent to the tumor. In the current in-vivo experiments performed on large animals, the modified clips were transported without difficulties to the point of interest and attached to the mucosa of the bowel. Using a laparoscopic approach, the detection rate of this system reached 65% when the sensor scanned the bowel at a speed of 0.3 cm/s, and applying slight pressure on the serosa. This value increased to 95% when the sensor was guided directly on the point of clip attachment. The detection rate dropped sharply when the scanning speed exceeded 1 cm/s and when the sensor-clip distance exceeded the cut-off value of 3 mm. In conclusion, the proposed detection system demonstrated its potential to offer a swift and convenient solution for the digestive laparoscopic surgeons, however its detection range still needs to be improved to render it useful for the clinical setting. Although these tumors are the ones most suitable for a minimally-invasive surgical approach (MIS)5, precise intraoperative identification of their position is difficult in laparoscopy since they are not visible from the serosal side while the haptic feedback offered by the laparoscopic instruments is significantly less reliable than palpation is for open surgery6.Due to larger availability of endoscopic diagnosis4. However, the endoscopic measurement of distances is fairly estimated because the colon is elongated and distended by insufflation during endoscopy, while small tumors are difficult to be visualized on CT or MRI.Currently, location of the tumor is approximated by integrating the length measured endoscopically from the tumor to the anal verge or dental arcade with findings from imaging radiology (computed tomography-CT or magnetic resonance imaging -MRI)8 and intraoperative endoscopy9 are the techniques most commonly used to aid in intraoperative location of these tumors. Both have their own disadvantages. The first requires compliance from the endoscopist, and has certain limitations related to the quality of the dye, depth of injection, or widespread staining of the surrounding tissues if injected intraperitoneally12. The latter is largely dependent on the availability of an endoscopic device in the operative theatre and is mainly performed in modern hybrid operating rooms13. Moreover it implies distension of the bowel with residual gas which impedes adequate visualisation during the subsequent stages of laparoscopic resection. Intraoperative ultrasound may be helpful in identifying the tumor, but it has limited sensibility, requires appropriate and expensive high-end devices, an experienced radiologist present into the operative theatre and, in MIS is furthermore restricted by the fixed position of the trocars14.Endoscopic tattooing15. The method allowed precise identification of the tumor in 6 of a total of 8 patients and looks quite promising. However it has the disadvantage of poor penetration of tissue, in the range of 2 mm, by the near infrared fluorescence especially with vertical illumination. It also requires an atypical near-infrared fluorescence imaging system to detect and display the image of the marked clips.Use of indocianin green as fluorescent marker attached to the jaws on standard endoscopic clips was also proposed in a clinical trial16 which attached a light emmiting diode to a coiled antenna creating a 9 × 2 × 2 mm device that could pass through the forceps aperture of a gastrointestinal endoscope and was deployed to the mucosa attached to a standard hemostatic clip. The system allowed detection of the clip in all 3 patients participating to the trial, however, there are still issues with transportation of the LED-antena units and their long-term attachment on the mucosa of the colon.Another interesting solution is described by Wada et al.Although the last reports are quite promising, the proposed methods are still in an experimental phase and require high-end devices. Given the actuality of the problem in our clinical practice and the lack of a convenient solution, we have tried to find an alternative approach to intraoperative tumor location during MIS, which avoids the disadvantages of the above-mentioned options. We also aimed to reduce the number of specialists and expensive devices required for detection, within the aim of increasing the utility of the technique in hospitals which have less advanced equipment and staff. In this respect, we have designed and constructed a sensing instrument compatible with laparoscopic surgery, capable to detect metallic tags placed endoscopically on the mucosa of the digestive tract  in the vicinity of the tumor within days or weeks before surgery, ideally at the time of the diagnostic endoscopy. By detecting these metallic tags, the surgeon is aware of the exact position of the tumor and thus can plan the resection accordingly.18, in which we have intensively tested its functionality in ex-vivo dry and wet lab experiments, on synthetic materials, biologic tissues and human surgical specimens. In this work, the primary aim was to evaluate the feasibility of the proposed detection system in “in-vivo” experiments, in conditions similar with the ones encountered in the operative theatres. The second aim of the study was to evaluate if the attachment to the deployment mechanism, and attachment of the clips on the mucosa, are influenced by the process of metal deposition.The system was presented already in our recent articlesThe principles of tumor localization can be briefly described as follows: a modified endoscopic hemostatic clip serving as metallic tag is placed endoscopically on the mucosal side of the gastric or colonic wall in the vicinity of the tumor at the time of diagnostic endoscopy or later, ideally between two weeks and two days before surgery. Multiple clips can be applied around the periphery of the tumor if desired. During the laparoscopic operation, the sensing instrument scans the serosa of the bowel in the segment where the tumor is supposed to be located based on measurements recorded in the endoscopic report and on information provided by sectional imaging. When the instrument detects one clip an acoustic signal is produced and the tumor is precisely located see Fig. .Figure 1In a particular manner, the inductive proximity sensors detect the presence of hemostatic metallic coated clips entering into their oscillating field, providing a target detection. The system contains an oscillator which creates a high frequency electromagnetic field that is radiated from the coil in the sensor front area.When this field contacts the conducting coated clips, a small current is induced within the hemostatic clips, which further generate their own electromagnetic field that interferes with the field originating from the coil. This causes a modification in the amplitude of the oscillations of the signals from the coil system. The output voltage should be calibrated to this modification.17, five types of instruments incorporating different inductive proximity sensors23 were constructed and extensively tested and optimized, with the aim to develop, verify and adopt the most appropriate clinical protocols for tumor detection. The process of development and construction, from watertight encapsulation of the inductive proximity sensor into stainless steel rods sheaths to fabrication of the electronic operation block module and elaboration of the swift connection between these two components is presented elsewhere18. The instrument was designed using a modular platform that allows widely-available sterilisation by autoclavation without damaging the electronic module.The detection instrument has been used inductive proximity sensors that have the capability to identify presence of metallic tags. In an extensive previous research workIn summary, the inductive proximity sensor is hermetically mounted on the distal end of a stainless-steel rod which resembles a laparoscopic instrument by having an outer diameter of 12 mm and a length of 45 cm. The 12 mm diameter was chosen to accommodate larger, 10 mm diameter sensors, which have more potent detection capabilities but it also has the disadvantage that it requires the larger, 12.5 mm laparoscopic trocars for introduction into the abdominal cavity. The junction between the sensor and the stainless-steel rod is hermetically sealed with a resin to withstand multiple sterilisations. The proximal end of the detection instrument has a length of 18.5 cm, is composed of a stainless-steel case which serves as handle for the instrument and was designed to comply with the ergonomics and manipulation properties required by the surgical team. It incorporates the electronic functional block and is hermetically closed with a metallic lid to ensure proper sterility. The electronic functional block was dimensionally scaled-down to fit into the stainless-steel case while the instrument was constructed using a modular platform that allows disconnection of the electronic block and sterilization of the sensor-case unit by autoclavation (45 min at 121 °C and 1.2 bar pressure) followed by swift plugging of the electronic block just before surgery in a sterile-controlled environment.The updated version of our instrument is shown in Fig. 17 performed in gaseous (air) and liquid  environments, and continued on ex-vivo surgical specimens 18, we have concluded that the 12 mm laparoscopic detecting system that incorporates a 10 mm diameter proximity sensor (IFS290 and E59M12C110C02-D1), offers the longest detection range and will be used in the “in-vivo” experiments. Both sensors, use a built-in microprocessor to provide smallest detection and errors that can be modified from the microprocessor software to intelligently detect and maximize sensor performance depending on the environment used. They are capable to perform these actions with accurate monitoring of very small changes in field saturation when the target moves in the detection field, then compares these changes to specific user-programmed values.Based on our previous research workThe conventional endoscopic hemostatic clips (Olympus HX-610-9090L and Olympus HX-610-135L) were chosen as metallic tags that should be detected by the sensing instrument, due to their large availability and possibility to be deployed anywhere along the digestive tract using standard endoscopic instruments and techniques. In order to increase the detectability of these clips, they were further engineered by surface depositions of nanometric layers of cooper (Cu), zinc (Zn) and gold (Au) in various layer thicknesses from 10 nm, 20 nm and 30 nm, and then increasing every 100 nm up to a maximum of 1 micron. The plastic side of the clip was protected by a custom-made shield.Deposition of thin layers of Cu, Zn and Au was done through Physical Vapor Deposition (PVD) technique. In this process, the material passes from a condensed phase to a vapor phase, and then back to a condensed thin film form. The targets used had a purity of 99.998%. Cu and Zn were chosen in an attempt to improve the detection range while Au was coated at the end of each deposition proccess  to ensure biocompatibility of the modified clip. Although their thicknesses have been intensively tested up to 1 micron, the detection randament decreases exponentially after 300 nm thickness with about 0.2 mm per 100 nm added thickness, regardless of the environment in which the first measurements were performed.Previous experiments performed by our research team on a multitude of clip combinations coated with various concentrations of Cu, Zn and Au, showed that the longest detection range was associated with the followig combinations: (1) Cu 200 nm + Au 10 nm; (2) Cu 300 nm + 48 Zn + Au 10 nm and (3) Cu 500 nm + 20 nm Au. Therefore, in the following in-vivo experiments, only these modified clip variants were used.The Karl Storz™ flexible endoscope with a 2.8 mm diameter working channel was used for the transport and deployment of the clip to the point of interest. The modified clip was placed into the standard cover of the usual Olympus HX-610-9090L or Olympus HX-610-135L hemostatic clips. The attachment tip of the clip, which is made of plastic, was not modified by the vapour deposition process and was supposed to fit easily into the hook of the operation wire. The clip was thus attached to the wire and carefully withdrawn into the working channel of the endoscope. Observations were made if the modified clip fitted inside the working channel and was able to be transported to the site of interest on the mucosa. Once the location of clip deployment was chosen, the slider was moved distally and the clip was deployed using a procedure similar with deployment of a standard hemostatic clip. The process is schematically drawn in Fig. 2/air mixture and N2O. Fentanyl  was used for analgesia and pancuronium (0.25 mg/kg/h) for muscle relaxation. The common carotid artery and internal jugular vein were surgically catheterized and connected to membranous pressure transducers for continuous measurement of mean arterial pressure and central venous pressure, respectively. Ringer lactate solution was infused continuously during the operation at a rate of 20 Ml/kg/h. Heart rate and rhythm were monitored by a surface electrocardiogram.The functionality and sensitivity of the detection system system was evaluated in “in-vivo” experiments performed on large animals. For these experiments were used two pigs with weights of 60 and 65 kg, respectively, operated laparoscopically in deep anaesthesia Fig. . After pExperiments were carried out respecting the European conventions and ARRIVE guidelines for animal welfare and were authorized by the decision of the Ethical Committee of the University of Medicine Cluj-Napoca No 156/02.04.2018. We also attest to informed consent for publication of identifying information/images in online open-access publication.In order to prepare the colon mechanically to create adequate conditions for intraoperative colonoscopy, animals were fed with 2 L of diluted polyethylene glycol solution (Fortrans) in the last 24 h before surgery and 4 h preoperatively with trans rectal instillation of one packet of Clismalax solution.24 and modified hemostatic clips were used for the experiment, the former ones acting as the control group. The clips were spaced at a distance of at least 5 cm from each other, the location of the clips being determined by the endoscopist. In one experiment the clip was placed through a trans-oral route into the duodenum using the same approach  using three trocars, one 10 mm trocar for the optics, one 5 mm trocar for an atraumatic bowel grasper and a 12 mm trocar for the 12 mm detection instrument. Concomitantly, the endoscopy team loaded the modified clip into the applicator of the flexible Karl Storz™ endoscope using the instrumentation and technique described in the previous chapter Fig. A. The enThe main investigator from the surgical team was blind to the exact location of the clip, he was only informed that the clip was either into the rectum or into the sigmoid, mimicking the information provided to the surgeon by the preoperative endoscopic measurements from the anal verge to the tumor. After each deployment of a clip, he attempted to discover its exact location by scanning the serosal side of the bowel Fig. . ScanninClips were attached to the mucosa of intraperitoneal bowel segments which had a maximum wall thickness of 2.5 mm. The stomach, which has a wall thickness exceeding 3 mm, was thus excluded and so were the colon from the ileocolic junction to the sigmoid which, in the swine, is spiral and has reduced peritoneal lining. Endoscopic access to the duodenum proved to be quite difficult due to the lenght and shape of the stomach and was abandoned after the first succesful attempt. Finally, the sigmoid and upper rectum were the segments which provided easy endoscopic access and had a wall thickness in the range of 2 mm considered adequate for the scope of the research.A total of 8 modified and 2 standard titanium clips were tested in two animals. In the first animal, 1 modified clip was introduced into the duodenum while 1 standard clip and 2 other modified clips were inserted into the rectum and sigmoid colon respectively.In the second animal were introduced 1 standard and 4 modified clips into the rectum and the sigmoid colon, up to a distance of 30 cm from the anal verge. The minimum distance between the clips was at least 5 cm.All modified clips coated with Cu 300 nm + Au 10 nm could be retracted into the working channel of the endoscope. They were also transported to the point of interest, released, deployed and attached to the mucosa of the intestine without significant problems. The endoscopic team did not experience differences regarding docking or deployment of the clip between the standard and the modified clips. It was thus demonstrated that covering the metallic part of the clips with nanometric layers of Cu and Au did not alter their spring mechanism or their functionality.The two unmodified titanium clips, one placed on the mucosa of the duodenum and the other on the mucosa of the rectum were not detected in any of the 10 scans for each clip. The detection signal was not obtained even when the endoscopist pinpointed the surgeon the exact position of the clip and the detector applied strong pressure on the serosa exactly above it. In conclusion, the detection rate of the standard titanium hemostatic clip was 0%.The modified clips did trigger a detection signal. The signal was present when the detector was above the clip and applied slight pressure on the serosa. If the detector was not in contact with the serosa, there was no detection signal. The overall detection rate of the modified clips, defined as number of passages over the clip that have produced a detection signal while the detector was moving along the serosa divided to the total number of attempts, was 65%. Localization of the clip by the surgeon into the indicated area was confirmed to be correct by the endoscopist in all cases. In light of these data, the sensibility and specificity of the detection system for the upper rectum and sigmoid with a wall thickness of 2–2.5 mm were 65% and 100% respectively.The speed of movement of the detector along the serosa of the bowel played also an important part since scanning with a speed of 1 cm/s was too fast for detection of the modified clips and needed to be reduced to 0.3 cm/s in all cases. Therefore, scanning a segment of the upper rectum and sigmoid 20 cm in length and 4 cm in width with a wall thickness of 2.5 mm had a 65% chance of precisely identifying the position of the clip within a maximum period of 132 s.Once the exact position of the clip was detected by the surgical team after those 10 detection attempts, placing the sensor exactly on the clip and applying slight pressure produced a detection signal in 95% of the cases. This experiment confirmed thus the reliability of the detection system in the “in-vivo” setting.When the colon was insufflated with air to confirm endoscopically that the searched clip was found, the detection signal became weaker or even disappeared if the clip was on the opposite wall of the rectum/sigmoid. The signal regained in intensity after exsufflation, highlighting that the presence of endolumenal air prevented the detector to press efficiently against the clip through the bowel wall and thus had an impact on the detection range.Precise intraoperative localization of endolumenal digestive tumors is the prerequisite for a successful operation. Nowadays, we experience a large enthusiasm to increase the rate of laparoscopic colorectal and gastric procedures while screening programs diagnose an increasing number of patients in the early stages of the disease. Therefore the proportion of patients with small tumors referred for surgery increases, and the surgeons might face a real challenge localizing the lesion especially when a minimally-invasive approach is used.25 and be provided with all necessary devices in a high-tech hybrid operating room13. However, the reality is that many surgeons still work in suboptimally equipped hospitals, have limited competences and often limited support from the endoscopist colleagues and, in these real-life circumstances, they still need to find the precise position of a small colorectal tumor to perform an adequate operation.The modern surgeon should ideally have a multidisciplinary training backgroundIn this regard, we have designed and constructed a detection instrument adapted to minimally-invasive surgery. Its tubular shape with a diameter of 12 mm allows introduction through laparoscopic trocars and its length is similar with that of laparoscopic instruments. The device is constructed in a modular fashion to allow sterilisation of the stainless-steel case without destruction of the electronic block, the latter being swiftly attached in the OR in a sterile environment. The instrument is easy to activate and use while the entire system it quite inexpensive, does not require presence of specialized personnel or expensive devices into the OR and is completely surgeon dependant.The detection instrument works in tandem with a metallic tag whom it detects. The principle of detection relays on the capacity of the inductive proximity sensors to detect variations into electromagnetic fields. The sensor contains an oscillator which creates a high frequency electromagnetic field. When a metallic tag is within this field, a small current is induced within it which further generates its own electromagnetic field that interferes with the field originating from the sensor. This causes a modification in the amplitude of the oscillations generatingan an output voltage can be calibrated and detected by the sensor. The sensors differ in their detection sensitivity. The ones chosen for our detection system, namely IFS290 and E59M12C110C02-D1, use a built-in microprocessor to provide the widest range of detection, even for the smallest signals. Moreover, the microprocessor software can be manipulated to intelligently detect and maximize sensor performance by developing detection capabilities depending on the environment used. One such unique feature offers the possibility to detect metal objects at a certain distance or band, while ignoring the targets which are located closer or further from the scanned area. The sensors are able to perform these actions with accurate monitoring of very small changes in field saturation when the target moves in the detection field, then compares these changes to specific user-programmed values.15 showed that the standard titanium clip has weak detection properties for a sensor with an outer diameter of 10 mm, which is the maximum diameter that can be considered for a laparoscopic instrument.The standard endoscopic hemostatic clip was chosen as the ideal metallic tag because it can be deployed anywhere in the long digestive tract of the humans using the standard endoscopic instrumentation. Data from our previous research17 showed that increasing the thickness of Cu deposition layers is associated with increased detection range up to a certain point followed by a paradoxal behaviour and a reduction of the detection range. By testing Cu layer thicknesses up to 1 micron, we have demonstrated that the detection range decreases exponentially after 300 nm thickness with about 0.2 mm per 100 nm added thickness, regardless of the environment in which the first measurements were performed.The clips were modified by nanoscale metal depositions of Cu and Zn using PVD  technology which complies with the modern requirements of purity for surgical and medical implants. An outer layer of gold (Au) was ultimatelly added to ensure biocompatibility of the coated clip. The PVD coating process is also environmentally friendly, greatly reducing the amount of toxic substances produced compared to other types of conventional coating involving liquid precursors or complex chemical reactions. In addition, the resulting metallic coatings have superior hardness, durability and wear resistance. The most frequently clip used in the present experiment was the Cu 300 nm + Au 10 nm. Previous work15, we have demonstrated that the system is viable and detects the metallic tag in the dry and wet laboratory experiments, both on ex-vivo animal tissue and on human surgical specimens. However, the questions remained if the modified clip can actually be hooked to the transport system and deployed by attachent to the colonic/duodenal mucosa on the point of interest using the standard endoscopic instrumentation. The present study demonstrated that the proposed system is working. Adding nanometer layers of Cu on the metallic part of the clip and covering it with other nanometes layers of Au for biocompatibility did not change the spring-lock mechanism of the plastic part of the clip and did not increase the size of the clip to the extent of not entering the 2.8 mm diameter working channel of the flexible endoscope. The modified clip was attached to the endoscope and deployed on the mucosa in 100% of the attempts.The most important achievement of this research is that the laparoscopic detection system has proven its efficacy into living tissue real-life situation. In our previous works2 reduced the detection signal either by increasing the distance from the detector to the clip, if the clip was attached on the oposite wall, or by interfering with the possibility to press on the clip against a more rigid structure like the retroperitoneum. The actual thickness of the duodenal, rectal or sigmoidian wall is roughly 2 mm. Therefore, we can state that the “in-vivo” real life situation detection range for the proposed system is actually around the value of 2 mm. If this cut-off value is exceeded, when fat pads or thickened intestinal wall is interposed between the clip and the detector for instance, the detection rate is expected to drop significantly.The second important question referred to the ability of clip detection in an “in-vivo” setting. In this respect, our study has a clear answer: modification of the hemostatic clip by deposition of nanometric layers of Cu and Zn rendered it visible to the detector. None of the total 20 attempts to detect the standard titanium hemostatic clip in the in-vivo setting was successful. This inability to detect repeated even when the endoscopic team directed the surgical team to place the detector on the exact spot where the clip is located. The modified clip however was detected in 65% of the cases when the serosa was scanned with a speed of 0.3 cm/s and slight pressure was applied on the serosa by the detector. This figure increased to 95% of the cases when the surgeon was guided on the exact spot where the clip was attached. These results prove the reliability of detection and suggests that this system has the potential to be useful in the clinical practice. However, the detection range is still far from satisfactory. Slight pressure on the serosa is still necessary for detection. In this regard, insufflation of the colon with COOne last observation from the present experiments is that detection is discriminative; the clips are selectively identified only when the sensor is placed above them. That allows detection of individual clips and adds precision to the detection process. This property is inversely proportional with the detection range. Since the detection range is still low, around 2 mm, the discriminative capacity of detection is high. Is it expected to decrease as the detection range improve.In conclusion, this study demonstrates that a modified endoscopic hemostatic clip can serve as a viable marker for tumor localization not only in an “ex-vivo” laboratory setting, as was demonstrated in our previous publications, but also in “in-vivo” real-life conditions. By changing its chemical structure, the clip became visible to the inductive proximity sensor and could be localized by the laparoscopic surgeon from the serosal side of the bowel during a minimally-invasive exploration, a process impossible when a standard endoscopic clip was used. However, the current detection range though viable biologic tissue of 2–2.5 mm is far from satisfactory for the clinical practice and that currently represents the major drawback of the proposed method.26 to the modified endoscopic clip that will be detected by an antenna included in the custom-made sensing instrument in a similar fashion with the method exposed in the present work.An important achievement of this work though was to establish a proof of concept which will be used in the future in our quest to develop a more efficient detection system. Our aim is to increase the detection range to at least 10 mm, value considered necessary to cover the thickness of the bowel and of the adjacent fatty tissue. One solution that we are evaluating in this respect is to attach a miniaturized radiofrequency identifier tagThe success of this quest will move the field of laparoscopic surgical oncology toward an era of effective, personalized tumor detection, allowing precise identification of tumor location and its margins solely by the surgeon, during all steps of the surgical procedure and without compromising exposure of the operative field and thus coming one step closer to the final goal which is to offer a better perspective for the outcome of our patients.


Clinical Neuroradiology was founded 30 years ago by the German Society for Neuroradiology with the aim of promoting “increased cooperation between clinically and diagnostically active physicians” [sicians” . The firIn the last 30 years we have seen an enormous development in neuroradiology. As the best example, 30 years ago the first aneurysm was treated with detachable coils, which has become the standard therapy today. Parallel to this development of the subject, the number of “full-time” neuroradiologists also grew, and in Germany, with a few exceptions, independent clinics and chairs for neuroradiology were established at universities. Today, the German Society for Neuroradiology is the largest national neuroradiological society in Europe with over 1000 members.Clinical Neuroradiology: The number of papers submitted has multiplied, the issues have become thicker, and the quality of the published papers has increased continuously. Ten years ago, we were able to report that the journal received an impact factor for the first time [The enormous development in neuroradiology is reflected in the development of rst time . A testiAlthough the increase in the impact factor by itself is an important quality feature, one must also consider the ranking in the two categories, “Clinical Neurology” and “Radiology, Nuclear Medicine & Medical Imaging”. In these categories, we have a stable position in the upper half.Clinical Neuroradiology has become internationally recognized and is now one of the most respected neuroradiology journals by both authors and readers. We have taken care to ensure that the quality of the contributions remains the most important criterion for publication and will remain so in the future. The topics of the papers submitted correspond to the current scientific activities of the neuroradiological community and are independent from the editorial board.The increase of the impact factor, the rising number of submissions and also the continuous growth of articles accessed and downloaded show that Clinical Neuroradiology and consider the published papers in your research. We on the Editorial Board assure a fair, rapid and robust peer review process. We are also available to you as contact persons for any questions or concerns at any time.However, we still see opportunities to improve and for this we still need your support. Please continue to read László SolymosiEditor-in-Chief


The application of a Thomas splint when managing a femoral fracture has the potential to be a painful experience for the patient. If movement of the injured limb can be reduced during the application then the patient will likely suffer less pain. In this report, we describe a method that enables the clinician to remove any slack in the tensioning system and apply the traction in a single movement. No additional equipment is required beyond the standard splint and skin traction apparatus. A pulley system is created using the cord, the splint and two overhand knots, minimising movement at the injury site whilst permitting sufficient traction to be applied. Once applied, it can be easily re-tensioned as the thigh musculature relaxes. We believe this method to be simple, more adaptable and quicker to apply than the current standard. The 'Thomas splint', introduced by Hugh Owen Thomas in 1865, was first used for the treatment of tuberculosis of the knee . The ThoThe benefits of early splinting in femoral fractures have been re-affirmed in a recent study. When comparing the pre-hospital application of the Thomas splint with the application after a radiographical diagnosis, the chance of requiring a blood transfusion was halved, and the risk of pulmonary complications fell from 12% to 0% .Traditional splinting involves the application of a skin traction. An appropriately sized, telescopic Thomas splint is applied with padding to the perineum. Slings sequentially elevate the thigh and leg with a slight bolster behind the knee. For transit, traction can be applied through the splint, opposed against the perineum, and with the cords from the stirrup tensioned distally using a windlass. When the patient has been transferred to a bed, the pressure on the perineum can be relieved by converting the splint from transit to static mode using weighted or balanced traction .There is rationale behind all of the elements during the application of the splint. Longitudinal elevation of the leg will flex the hip and de-tension the Iliopsoas tendon. It will also lift the posterior thigh/buttock off the padded hoop and reduce the risk of pressure-related soft tissue injury. Flexion of the knee will de-tension the hamstring and gastrocnemius muscles, both of which cross the joint. This may aid in reducing any muscular spasm causing overlap or shortening of the fracture. It may prevent posterior displacement of the distal femur and will improve rotational control of the leg distal to the fracture.The splint, padding and slings are sized and prepared in the conventional manner . Two nonWith friction eliminated, this pulley will theoretically provide a 3:1 mechanical advantage. For every 3 cm of cord pulled longitudinally, it will apply a further 1 cm of traction. When 1 N of force is applied to the free cords it will achieve 3 N of force in traction. The application of a Thomas splint can be painful for the patient. To help tolerate the procedure, the patient should be administered appropriate analgesia. The splint should be fully prepared in advance to ensure no delay in application once it is commenced. The use of a pulley mechanism to produce traction within a Thomas splint is a re-application of a historical concept. H.M.W. Gray's text 'The Early Treatment of War Wounds' depicts a Thomas splint applied to a soldier. Looped twice between the end of the splint and the boot clip is a length of cord , which cThe modernisation of the technique using a cord pulley system was described in 2014 ; howeverThe technique we present both simplifies and improves upon those formerly described. The disposal of the windlass removes the requirement for the two-stage tensioning required in traditional application. When the muscular spasm around the fracture relaxes, a re-tensioning of the traction may be required. The final knot may need to be released and the cords re-tensioned. A shoelace bow knot will allow this to be completed with ease . The knoWe determined the traction force that could be achieved using a standard Thomas splint. A Newton meter was suspended between the proximal end of the splint and a foot plate removed from a skin traction stirrup. Traction was then set up distal to this in a traditional manner. The slack was taken up as tightly as possible and a reef knot was tied. The windlass was applied and tightened until it could be tightened no further and a reading was taken from the meter Figure .Traction was then set up with the pulley system that we describe and a reading was taken from the meter Figure .This was repeated five times with each traction method to achieve an average.The mean maximum force achievable by a windlass was 92 N before it became too tight to wind. The mean maximum force generated by our method that could be successfully tied off was 138 N. A weight of 7 kg is suggested as an appropriate traction weight when using traction over a pulley at the foot of the bed . This wiAfter 156 years of its introduction, Thomas splint remains in frequent use throughout the world. The advantage it provides is still apparent with recent evidence suggesting that early application may reduce complications associated with the fracture. We have described a method in which the use of loops in the cord can create an advantageous pulley, thus removing the need for the windlass. We believe this method simplifies the process of applying adequate traction whilst allowing for the easy re-tensioning following muscle relaxation.


Re = 100 at lower activation energy and gives the total maximum enthalpy change in the tubular reactor. Observing the relationship between Sherwood numbers to Nusselt numbers, it was deducted that the convective heat transfer is opposite to convective mass transfer for high Reynolds numbers.In this article, we are focusing on heat and mass transfer through a Multicomponent tubular reactor containing a cooling jacket by thermal decomposition of propylene oxide in water. The chemical reaction is an irreversible, 1st order reaction and an exothermic reaction that yields propylene glycol with enthalpy = −84,666 J/mol. The constant rate of the reaction is followed by the Arrhenius equation in which the activation energy is taken on a trial basis in the range from 75,000 to 80,000 J/mol with a fixed frequency factor. For the fluid to flow, the Reynolds number is kept in the range from 100 to 1000. The three partial differential equations of mass, momentum, and energy are coupled to study heat and mass transfer in a tubular reactor by using the chemistry interface in COMSOL Multiphysics 5.4. The initial concentration of propylene oxide is tested in the range from 2 to 3% and the thermal conductivity of the mixture is tested in the range 0.599–0.799. It was found that the amount deactivated of the compound decreases with an increase in Reynolds number. Propylene oxide is decomposed at about 99.8% at  Also, millions of chemical species interacting with water are used to model and optimize the thermal distribution and mass distribution in tubular reactors in many industrial applications to make the required product quickly7. Various reactors have been made that are capable to remove or use the minimum amount of compounds that involve the carbon oxides and hydrogen bonds to optimize the enthalpy or entropy for the chemical reaction under observation10. Large industrial applications are founded on the side. The propylene oxide is simply called epoxy propane and is included in the list of the organic compound. It is the chemical compound that is almost used in chemical reactions which are intermediate and widely used in the chemical industries to yield commercial products. It is also included in the list of 50 compounds that are widely used for the required production and annual demand is increased up to 14 billion pounds. The chemical reaction of propylene oxide with water produces propylene glycol which is largely used as an anti-caking agent, Antioxidant, Carrier, dough-strengthener, emulsifier, moisture-preserver, and a texturizer. The application of propylene glycol is found in making and caring the foods. The idea behind using the chemical reactions under the fluid dynamics problem might be whether someone is interested to increase the temperature or want to decline it according to their requirements. Moreover, to run the wind turbine machine, the enthalpy change needs special attention in recent works. While a certain compound reacts decomposes in water, releases energy, or absorbs energy (exothermic and endothermic reactions). To get a better advantage from the chemical reaction, it is always necessary that whatever the species are used in the reactors, they must react chemically with each other to give/take a certain amount of energy. According to collision theory, a sufficient amount of energy should be provided to a certain amount of reactants to perform the chemical reaction with each other13. Due to this reason, in the channel, sufficient activation energy should be provided to the reactants so that they can perform a precious chemical reaction under the component to give a certain amount of the products which can fulfill the researcher's requirement in the vessel or components16. It is also known that the thermal conductivity of a chemical mixture or base fluid can majorly affect the thermal distribution in the reactors20. The amount at which the chemical species are diffused in the reactor can majorly impact the rate of reaction. Optimizing the thermal and mass transfer parameters are the fundamental requirements of today's engineering industries23. The enhancement in thermal characteristics due to the chemical processes is the fundamental requirement in the engineering field and industrial sciences. Here, we are going to report the following literature review:Multicomponent tubular reactors as vessels are widely used to investigate the heat and mass transfer problems under the chemical reactions at different boundary conditions24. Using the Soret and Dufour coefficients, a heated enclosure domain was numerically examined by double-diffusive impact with the mixing of Al2O3-H2O nanofluids25. An infinite vertical plate was observed for impacts of first-order homogeneous reaction for the unsteady flow for constant mass and heat distribution24. A study of magneto-hydro-dynamics MHD flow was done in account to observe a vertical stretchable plate with the permeable surface under the chemical reactions26. A novel study was performed by assuming that the plate contained in the uniform porous medium and continuously moved with constant speed in the presence of the magnetic field. Another investigation for consequences of chemical reactions as well as radiation on the unsteady MHD and free convection was done to observe the flow past through a semi-infinite moving plate in the presence of heat source or suction31. With the implementation of thermo-analytical techniques, the decomposition of barium carbonate was investigated and found the activation energy of barium carbonate was for the initial stage using the gravimetric data32. The flow of heat and the mass transfer in a packed bed reactor was investigated by30 under the conditions of reacting and non-reacting species. In the article, the most ordinary sample of the reactor was discussed which was containing cooled walls.34 Analyzed the consequences of homogeneous and heterogeneous reactions in the chemical engineering problems on the diffusivity of species in the nanofluids under the presence of the magnetic field. The fluid under consideration was an idealized fluid i.e. the fluid which is not made of electrons. The mass and thermal diffusion were examined, where the intention was to compare and contrast the mass diffusion and the thermal conduction for the two-dimensional plug flow concerning the convective property36. The counter flow diffusion of chemical species hydrogen and oxygen was studied by37. In the article, the most critical points related to thermodynamic and transport properties were discussed. A theoretical study was done on the consequences of the homogeneous and heterogeneous chemical mixture over the diffusion of species in the chemical mixture where the surface is moving with constant speed or velocity38. One dimensional steady-state model was developed on account of a tubular reactor in the procedure for naphtha cracking39. About 90 species with 543 reactants were used to implement a free-radical scheme. The aim behind the study was to maximize the operating. Often the field of computational fluid dynamics CFD shows the complex picture of the stable radial flows40. It describes the local heat transfer can be connected with the local field of flow. It was also deducted that some heat transfer parameters are less or not affected by the pressure as well as wall temperatures41. With the implementation of finite element-based software COMOSL Multiphysics 5.4, various achievements were gained and successfully describe the characteristics of fluid dynamics problems with the help of fluidic and thermal parameters in the rectangular channels with and without obstacles with screen boundary conditions. The results were displayed with graphs and tables, similar to those reported in Refs.46. The numerical results contrast with the asymptotic solution gained by the implementation of the screen boundary in problems.Thermal and mass transfer in a vertical-cavity heated below was examined numerically to form the correlation between the dynamical and thermal non-dimensional parametersIn the current research article, we are going to focus on the heat and mass transfer in the Multicomponent tubular reactor under the decomposition of propylene oxide in water with the standard temperature of 25 °C with different activation energies, Reynolds number, and thermal conductivity of the mixture. Mainly, we are focusing on the full decomposition of the compound propylene oxide in water and suggest the critical Reynolds number for the problem to give a maximum decomposition of propylene oxide. Then we determine the total enthalpy change of the system against the tubular reactors by fixing two of the three parameters. The maximum total enthalpy change will be calculated and suggested the required parameters for it. Finally, the Sherwood-Nusselt number relationship will be focused on through the graphs.L = 1 m with radius Ra = 0.1 m is under observation for measuring parameters of mass and heat transfer see Fig. T0 = 273 K. The propylene oxide is disintegrated in water to give propylene glycol in which the water is being in excess and the reactor is keeping at the reference temperature of Tref = 293 K. The chemical reaction is of the first order, irreversible, and exothermic reaction that releases the energy of A Multicomponent tubular reactor of length 1 and is the rate of reaction in mol/s and k1 is rate constant given by the Arrhenius equation:R is the universal gas constant.Where RE) in the range of 75,000 to 76,000 in J/mol. For the current problem, on the trial basis, the activation energy is taken in the range from 75,000 to 80,000 J/mol with fixed Arrhenius constant A (frequency factor) of 16.96 × 1012. Moreover, the initial amount of propylene oxide cpo is tested from 2 to 3% to the amount of water to give a diluted mixture for transportation. The inlet of the tubular reactor is facing a constant temperature of Tin = 312 K. The consequences of the hydrolysis reaction over the propylene oxide under the laminar fluid flow with the constant viscosity, we are developing the Reynolds number in the range from 100 to 1000. That range will enhance the total flow rate at the inlet of the reactor in the range from 3.14 × 10−6 to 3.14 × 10−5 in m3/l. Equations , L is the length of the reactor (m).The total enthalpy of the system can be measured by:50. Originally, the Churchill-Bernstein Eq.  is achieved at Re = 1000, E = 80,000 with k = 0.799.Finally, we are going to display the percentage deactivation in the amount of propylene oxide for all cases discussed for the current problem. The table is also including the variation of thermal conductivity of the mixture. Table By definition, the enthalpy of a system is the sum of the internal energy and the product of mass and volume. The product of pressure and volume causes the atmosphere for the system to do non-mechanical work. Generally, it is known that it is almost unlikely to determine the total enthalpy of the system. The reason behind this we do not know the total energy of the system and in short zero points of the system is undetermined. Assuming all factors generating the internal of the system are known as in our simulation then we could determine the total enthalpy and the change in enthalpy of the system. Applications of enthalpy are widely found in refrigeration and in combustion problems where the heat through vapors is found beneficial..The heat and mass transfer are investigating in the current problem through the decomposition of propylene oxide and water (hydrolysis) to form propylene glycol. The reaction is an exothermic reaction and the standard rate of reaction is E. For Re = 100 and k = 0.599, 0.799, the total enthalpy is increasing first attempts a maximum value then it is declined to see Figs. Re = 100 at k = 0.599 and 30.7% for Re = 500 at k = 0.799 see Figs. Re = 100, the total enthalpy is increasing comparatively through the length of the tubular reactor see Figs. The total enthalpy is presented in Figs. k = 0.599 the maximum total enthalpy is increasing about 4% as we increase Re from 100 to 1000. Similar increments can be seen for 2.5% and 3%. Further, we are presenting the tables for the maximum enthalpy change in the system at different activation energies, initial concentration, and thermal conductivity of the mixture see Tables Re = 100 and Re = 1000 respectively. It is clear from these tables the maximum enthalpy change is decreasing with the increase in activation energy by fixing the thermal conductivity as well initial concentration. With fixed activation energy as well the initial concentration the maximum enthalpy change is showing a little bit negative response with the thermal conductivity of the mixture. Observing the particular cases in the tables, it is clear that the total maximum enthalpy change, for the case of Re = 100 is always greater in the case of Re = 1000. It is evident from the table that the total maximum enthalpy change is achieved at Re = 100, E = 75,000 J/mol, k = 0.559 with 3% initial concentration. We see the maximum total enthalpy near the inlet of the channel when Re = 100 in Fig. Further, we are observing the graphs of total enthalpy with the increase of Reynolds number up to 1000. With the increase in Reynolds number, the total enthalpy of the system is increasing for a constant thermal conductivity of the mixture see Figs. Re = 100 and Re = 1000) and thermal conductivity of the mixture (k = 0.599 and 0.799). The variation of the Sherwood number against the Nusselt number is checked by increasing the activation energy as well as the initial concentration of the compound propylene oxide.Sherwood number is well known as the ratio from convective mass transfer rate to diffusion rate. It is well known as the mass transfer Nusselt number. A change in the Sherwood number might be the reason for changes in convective mass transfer rate or diffusion rate across the boundary of a system. For heat and mass transfer to know the convective mass transfer rate and diffusion rate are essential. That's why the non-dimensional Sherwood number is used for the purpose. Similarly, the Nusselt number is known as the ratio between convective to conductive heat transfer. An increase in the Nusselt number means either the convection is enhanced in the domain or the conduction procedure is declined in the system. In the current section, we are going to focus on the relationship between the Sherwood number and the local Nusselt number along the length of the tubular reactor. For this purpose, we are presenting the graphs by fixing the Reynolds number (Re = 100 with k = 0.559, the critical minimum value is declined about 31.5% see critical minimum value in Fig. k = 0.799, the critical minimum value is declined by about 33.3% see critical minimum value in Fig. It is clear from the Figs. Re = 1000 in Figs. Re = 1000 with the activation energy of 75,000 J/mol with the initial concentration of 2% and 2.5% in Fig. Re = 100 and Table Re = 1000, it is clear from the table the minimum critical value of the Sherwood number shows a little bit positive response against the thermal conductivity of the mixture for all the cases.For high Reynolds number A = 16.96 × 1012. The mass balance, momentum balance, and energy equations were coupled to establish the finite element simulation in COMSOL Multiphysics 5.4. The various simulations were obtained by altering the Reynolds number from 100 to 1000, the thermal conductivity of the mixture from 0.559 to 0.799; the initial concentration of the propylene oxide from 2 to 3% with, and activation energy from 75,000 to 80,000 J/mol. Water was being in excess in the mixture, therefore the total rate of reaction is depending upon the concentration of propylene oxide. The rate constant was given by the Arrhenius equation. The results were displayed through the graphs and tables for the deactivation of propylene oxide, formation of propylene glycol, total enthalpy, maximum total enthalpy change, and the Sherwood–Nusselt number relationship. We made the following conclusion points:Fixing other parameters in the current problem the decomposition of the propylene oxide decreases with the increase in the activation energy.The amount of deactivation of the propylene oxide possesses a negative relationship with the increase of Reynolds numberWith the increase in thermal conductivity of the chemical mixture, the deactivation of propylene oxide is a little bit affected.Re = 100, E = 76,000 J/mol with the k = 0.559. Whereas the minimum decomposition of about 13.1% is achieved at Re = 1000, E = 80,000 J/mol, and with k = 0.799The maximum decomposition of the propylene oxide is achieved by about 99.8% at The formation of the propylene glycol does majorly impacts the total maximum enthalpy change at the lower Reynolds number. The maximum total enthalpy is decreasing with the increase in activation energy keeping other parameters constant.For the lower Reynolds number, the total enthalpy first increases up to the maximum value then decreases throughout the length of the reactor. But for the high Reynolds number, the total enthalpy is always increased. Therefore, we suggest the application of decomposition of propylene oxide can be used in a turbine to create electricity.Sherwood number is always decreasing with the increase in local Nusselt number for the higher values of the Reynolds number whereas for low or moderate Reynolds number the relationship cannot be judged because the Sherwood number is decreasing first up to critical minimum value then increases. This means the diffusion rate is dominated over the mass transfer rate with the increase in Reynolds number.Sherwood's number is decreasing with the increase in activation energy. This means the convective mass transfer rate is dominating over the diffusion rate of propylene oxide.Sherwood number also shows a positive relationship with the increase in Reynolds number. It means the convective mass transfer rate is increasing with an increase in Reynolds number.The heat and mass transfer in the reactor of unit length were investigated with the thermal decomposition of propylene oxide in water. The chemical reaction engineering module of COMSOL Multiphysics 5.4 was used to observe a chemical reaction in the Multicomponent tubular reactor containing a cooling jacket of the fixed temperature around the surface. To perform the first-order irreversible chemical reaction between the molecules of water and propylene oxide, activation energy in the range from 75,000 to 80,000 J/mol was tested with the standard enthalpy of reaction of


The ischiofemoral distance (IFD), defined as the distance between the ischial tuberosity and the lesser trochanter of the femur, is gaining recognition as an extra-articular cause of hip pain. It is unknown whether the IFD is influenced by the frontal knee alignment. The aim of this study was to determine the influence of realignment surgery around the knee on the IFD. It was hypothesized that valgisation osteotomy around the knee is associated with reduction of the IFD.A consecutive series of 154 patients undergoing frontal realignment procedures around the knee in 2017 were included in this study. Long-leg standing radiographs were obtained before surgery and postoperatively. The IFD was measured between the ischium and the lesser trochanter at three different levels  on standardized long-leg radiographs with the patient in upright standing position. The knee alignment was determined by measuring the hip knee ankle angle, mechanical lateral distal femur angle and the medial mechanical proximal tibia angle. Linear regression was performed to determine the influence of the change of frontal knee alignment on the IFD.p < 0.001). Valgisation osteotomy around the knee induced a significant reduction of the ipsilateral IFD (p < 0.001), while varisation osteotomy induced a significant increase (p < 0.001). The amount of ISD change was 0.4 mm per corresponding degree of change in frontal knee alignment.Linear regression showed a direct influence of the overall change in frontal knee alignment on the IFD of the hip, regardless of the site of the osteotomy (β-0.4, confidence-interval − 0.5 to − 0.3, These findings are relevant to both the hip and knee surgeons when planning an osteotomy or arthroplasty procedure. Correction of a malalignment of the knee may resolve an ischiofemoral conflict in the hip. The concept deserves inclusion in the diagnostic workup of both the hip and knee joints.IV. Given the fact that the knee is connected to the hip by the femur and to the ankle by the tibia, it is reasonable to expect that the alignment of one joint is likely to exhibit an influence on adjacent joints , 15, 20.This study will be dealing with the effect of surgical realignment of the knee on the distance between the ischial tuberosity of the pelvis and the lesser tuberosity of the femur, also known as the ischiofemoral distance . The iscThe association and relationship between the frontal alignment of the knee and the ischiofemoral space of the hip is unknown. The clinical relevance here may be seen in the need to address a problem around the knee in order to resolve a hip problem. This emphasizes the novelty aspect of the current study. The aim was therefore to examine the influence of correctional osteotomy around the knee on the ischiofemoral distance of the hip. Given that adduction of the femur is possibly necessary to maintain contact between the foot and the floor in a valgus knee, it was hypothesized that valgisation osteotomy around the knee is associated with reduction of the ischiofemoral distance.A consecutive series of 154 patients undergoing osteotomies around the knee in the year 2017 were considered eligible for inclusion in the study, provided that pre- and postoperative radiographs were available. Patients were excluded if a multiple plane correction was performed, no magnification device was present on the postoperative radiograph or  if the postoperative image quality was poor. Considering the above criteria, 154 knees of 154 patients undergoing osteotomy were considered eligible for retrospective data retrieval and inclusion in the study  was performed as described by Staubli and Lobenhoffer using a TomoFix™ MHT plate fixator  , 17, 23.Long-leg weight-bearing radiographs were obtained in accordance to Paley using a 1.3 m cassette . Long-leg antero-posterior standing radiographs were obtained with the patient standing in a bipedal stance in front of the long film cassette. The X-ray tube was positioned 305 cm away. The selected film cassette was of sufficient length to capture the hips knees, and ankles. The magnification with this setup was approximately 5%. A magnification device  was used to calibrate the radiographs. The X-ray beam was centered at the level of the knee joints.Radiologic technical assistants were instructed to position both legs with the patella centred between the femoral condyles pointing forward. It was of ultimate importance to ensure a standardized radiography. Preoperative radiographs were obtained prior to surgery for planning of the deformity correction and were repeated postoperatively after union at the osteotomy site and recovery of limp-free weight bearing.® software . The following parameters were measured in accordance with Paley [Radiographic parameters were determined with an accuracy of 0.1 mm or 0.1° using mediCADth Paley : mechanip value of < 0.05 was considered statistically significant. SPSS version 24  was utilized for analysis. Post hoc power analysis showed that a power of 95% was achieved for pre- and post-adduction of the femur as the primary research question, given the sample size of 154 patients and α-value of 5%.Continuous variables were presented as mean ± standard deviation and range. Linear regression was performed to determine the influence of the variety of input variables on the ischiofemoral distance. Comparison between means was performed using the Wilcoxon–Mann–Whitney-Test. A The examined cohort of patients included 154 knees of 154 patients undergoing osteotomies around the knee due to a bony malalignment and corresponding symptoms. The mean age was 51 ± 11 years. There were 96 male patients and 58 females. All osteotomies performed were around the knee and included 73 high tibial osteotomies (HTO), 54 distal femur osteotomies (DFO) and 27 double level osteotomies. Of all osteotomies, 118 were valgisation osteotomies and 36 were varisation osteotomies. Radiographic findings of knees undergoing varisation and valgisation are illustrated in Tables p < 0.001), as demonstrated by the FAA angle. Figure p < 0.001) and therefore induced abduction of the femur. Figure The results show that a valgisation osteotomy around the knee was associated with an increase in the adduction of the femoral shaft in relation to the pelvis (p < 0.001). A more valgus frontal knee alignment was associated with a reduced ischiofemoral distance  and the ischiofemoral distance  − 0.5 to − 0.3, p < 0.001)  Fig. b. An inc01) Fig. c.p < 0.001) .It was also shown that a more valgus overall frontal knee alignment (HKA angle) induced adduction of the femur in relation to the pelvis in an upright standing position (β 0.4, CI 0.3–0.5, This study demonstrated an association between the frontal knee alignment and the ischiofemoral space of the hip joint. Realignment surgery around the knee has shown a significant influence on the ipsilateral ischiofemoral space regardless of the site of the osteotomy. Valgisation osteotomy resulted in a decrease in the ischiofemoral space, varisation osteotomy in an increase.The novelty aspect of this study is underlined by consideration of the frontal knee alignment in the overall concept of extra-articular hip impingement. The introduction of this component into the overall hip workup could optimize individual treatment planning and ultimately widen the spectrum of therapeutic treatment options.Ischiofemoral impingement is increasingly being recognized for its role in the pathomechanism of atypical hip pain and particularly in conjunction with posterior hip impingement , 16, 22.Therefore, it is fair to underline the need for appreciating the knee alignment in the overall workup of a symptomatic hip. Realignment surgery around the knee may resolve a bony conflict in the hip. Especially, if the obliterated ischiofemoral space is resultant to a valgus knee alignment. A concept that must be understood.The concept is also relevant to the knee surgeon in the overall workup of the painful knee and when planning knee alignment correction. It is of upmost importance to appreciate the influence of the correction on the adjacent hip joint to prevent the occurrence of an unwanted effect. Given that pain disorders of the ankle have also been reported as a result of realignment of the knee, it can only be underlined that there is a true need of deepening the understanding of limb realignment with particular emphasis on further developing planning tools , 5, 10.Figure The plausible explanation can be seen in the idea that after a knee valgisation osteotomy, adduction of the femur would have to occur to maintain contact between the foot and the floor, this would ultimately result in the reduction or obliteration of the ischiofemoral distance. In patients with a naturally narrow ischiofemoral space, impingement may occur Fig. .The limitations of this study could be seen in the fact that femoral torsion was not determined and included as an input variable. Despite the valuable input, this measure would have resulted in radiation exposure violating ethical standards. To account for that problem, patient who underwent osteotomies around the knee were considered to control for most variables including torsion. Furthermore, a three-dimensional determination of the ischiofemoral space would provide a more accurate depiction. This would mandate complex imaging in a functional standing position. The same applies for dynamic testing. Given that the aim of this study was to prove the concept, the authors agreed on the sufficiency of the design chosen in this study.The results of this study highlight the influence of the frontal knee alignment on the ischiofemoral space of the hip. Correction of a malalignment of the knee may resolve an ischiofemoral conflict in the hip. The concept deserves inclusion in the diagnostic workup of both the hip and knee joints.


The aim of this study was to evaluate the influence of the introduction of online podcasts as part of the main lecture series in orthopaedics on the number of lecture attendees, the examination results and the assessment of teaching by the students. Additionally, we evaluated the use of other media for examination preparation.At the beginning and end of the lecture series questionnaires were handed out to the students to evaluate their attitudes towards attending lectures, the use of video podcasts and examination preparation. In addition, the number of lecture attendees and podcast usage during the semester were counted and the statements of the students in the evaluation assessments of orthopaedic teaching were evaluated. The examination results were correlated in a statistical analysis with the learning materials provided by the students for examination preparation.At the end of the lecture series, 284 students stated that they used the lecture podcast about twice as often as attending lectures; however, for the majority of the students the provision of a video podcast was no reason not to attend the lecture. For example, 37.2% stated that they never and 26.8% stated that they rarely had not attended the lecture by providing the podcasts. Of the students 91–95% considered the availability of lecture podcasts to be a rather meaningful or very meaningful supplement to the lecture visit. Students increasingly used digital media to prepare for examinations instead of using traditional analogue methods. None of the learning methods or materials examined showed a statistically significant advantage in examination results.Students in the age of digitalization use a variety of learning materials and are no longer bound to classical analog teaching methods. The use of online podcasts had no negative impact on examination performance. Most students perceived lecture podcasts as a useful supplement to lecture attendance. The students praised the expansion of the teaching curriculum to include additional digital offers with positive comments in the evaluations, but without achieving an improvement in these student evaluations. Digitalization has an enormous impact on the world of working  and teacA study conducted by the University of Leipzig in 2016 examined the influences of Internet-based media use in Germany. It was found that only 28% of the participants surveyed actively used the online media in classes. The main reasons given against the use of Internet-based media in classes were increased time expenditure and a lack of personnel support. Online media, such as interactive case studies, podcasts and subject-specific apps were rated as suitable for use in teaching. Social media such as Facebook and Twitter were rated as unsuitable for use in classes .The recording of video podcasts in university teaching has been increasingly used since the beginning of the twenty-first century  either aThe effectiveness of video podcasts as teaching tools has been studied from different angles: Early studies concluded that a classical video podcast that combines the audio or video files recorded during a course with the lecturer’s slides can be as effective as traditional lectures , 23, 25.In the winter semester 2018/2019, video podcasts of lectures were recorded for the first time in the main lecture series of orthopaedic medicine at a Central German university and made available to students in a password-protected area . The aim of this study was to determine the influence of this change in teaching curriculum on examination results, attendance at lectures and the evaluation of courses by students.Is the provision of video podcasts a reason for students not to attend more or less frequently the facultative lectures of orthopaedics?Which media do the students use to prepare for the examination and when?Does the use of video podcasts have any influence on the examination results of individual students?Specifically, the study aimed at answering the following questions:Additionally, the use of media preferred by students for examination preparation was analysed to classify the role of lectures in the context of teaching media in times of digitalization. We hope to be able to make recommendations for teaching in orthopaedics and trauma surgery on the basis of the results.The video podcasts were a classical combination of the lecturers’ slides in Powerpoint™ format  and simultaneous audio recording by Camtasia Studio 9  of the lecture. Of the 26 lectures held 21 were recorded as podcasts.The video podcasts were made available in the password-protected student portal of the medical faculty at the end of the lecture week and were activated for all students of the ninth semester of human medicine until the end of the winter semester 2018/2019. In addition to the 21 lectures, the lecture slides were provided in PDF format  before or after the respective lecture.In the winter semester 2018/2019 there were 255 students enrolled in the ninth semester of human medicine, which includes the orthopaedic lectures and examination. Additionally, 51 students of other study semesters participated in the obligatory final examination of orthopaedics and were able to attend the lectures or use the video podcasts.The data were determined by means of three questionnaires, the continuous counting of lecture attendees, the recording of the number of podcasts retrieved from the student portal, the evaluation of the examination results and the evaluation of the student evaluations of the orthopaedic lecture series over the past 3 years Fig. .Fig. 1DaThe number of attendees was counted at the beginning of each lecture. The system of the student portal enables retrieval of the video podcast to be recorded as well as the time of the retrieval.The survey on students’ motivation to attend lectures, their attitudes towards the use of video podcasts in teaching, their preferred learning materials and their preparation time for the final examination was carried out in an anonymous questionnaire at the beginning and end of the lecture series and evaluated with EvaSys .3 questions about the previous attendance of lectures and the intention to attend lectures in the upcoming winter semester4 questions about experiences and settings for video podcasts1 free text field for any comments on the use of podcasts in student teaching.The first questionnaire was answered at the beginning of the first facultative lecture in the form of a sample of 85 students. It was divided into:2 questions about the actual attendance of lectures in the past winter semester4 questions about students attitude towards video-podcasts2 questions about the possible waiver of the lecture visit by the provision of video podcasts of the lectures and, if applicable, the reasons7 questions about the time of examination preparation and the preferred learning materials (multiple choice).The second questionnaire was distributed at the end of the lecture series as part of a compulsory course and completed by 284 students. It was divided into:2 questions about setting up video podcasts1 question about attending lectures in orthopaedics last winter semester1 question about the preferred learning materials for examination preparation.A third questionnaire was also handed out before the compulsory examination and the student’s matriculation number could be voluntarily provided. The results of this questionnaire could then be correlated with the examination results. The questionnaire was completed by 225 students. It was divided into:p < 0.05.The data obtained in the third questionnaire were correlated with the examination results of the students using the Spearman rank test. The program SPSS  was used and the significance level was fixed at All participating lecturers had consented in writing to the publication of the lecture slides as podcasts. No patient data were published in the lectures. All students completed a declaration of consent to the use of anonymized data, in particular examination results, as part of the survey. In the absence of consent or rejection, the student was not included in the analysis.Of the students surveyed at the beginning of the lecture period (questionnaire 1) 79% stated that they would like to attend more than half of the orthopaedics lectures Fig. a. In theThe lecture series had an average of 44 visitors per lecture and the podcasts had an average of 78 hits per lecture Fig. . LectureWith 83.7%, the most popular learning material for examination preparation among the students surveyed was the lecture slides provided by the lecturers in PDF format. This was immediately followed by the online learning tool AMBOSS , which was used by 82.3% of the students for examination preparation. Of the students 60.4% stated that they had prepared for the examination with the podcasts of the lecture and 30% of the students stated that they attended the classical lecture to prepare for the examination. Other learning materials (23.3%) and textbooks (14.8%) were only used by a few students for examination preparation , 95 students grade 2 (≥80%) and 27 students grade 3 (≥70%).p = 0.3064). Additionally, there was no statistically significant correlation between the examination results and examination preparation through attendance at lectures , use of lecture slides , textbooks , AMBOSS  or other learning materials . Nor did the frequency of attending lectures    wanted to attend more than half of the orthopaedics lectures Fig. a; howeveThe video podcasts were used about twice as often as the lecture visit for examination preparation Fig. , this asOnly 13% of the students surveyed answered the concrete question of how often they had given up attending lectures due to the provision of a podcasts, with always, while 23% said they had done so frequently Fig. . This obMattick et al. compared the number of students attending facultative telemedical courses and courses with a lecturer present in 2003/2004. They found no statistically significant difference between the numbers of participants for both groups. Interestingly, Mattick et al. also described the trend observed by us that as courses progressed, fewer students participated in facultative courses with a lecturer present . Later, According to Kuhn et al. almost all medical students  make intThere are several studies on the influence of video podcasts on medical examination results , 21, 22.In the final evaluation of the orthopaedics lecture series, the students gave positive feedback throughout for the provision of online podcasts; however the thematic overlapping of lecture topics, an overloading of individual topics and a missing common theme during the lecture series were criticized. The statements of our students in the free text responses corresponded with the observations of Schreiber et al. who in their previously described experimental set-up had the students evaluate both the quality of the lecture and the online podcasts. The presentation and content quality of the podcasts were consistently rated somewhat worse than that of the lectures; however, the students praised the possibility of flexible learning over time with an online podcast and the ability to pause the podcast, repeat specific sections or the whole podcast .Ultimately, the quality of the lectures in terms of content, an interdisciplinary structure and the lecturers’ lecturing skills seem to have been decisive for the students’ assessment.From the perspective of the lecturers, a critical aspect of the provision of online podcasts as part of a lecture series which has to be discussed, are data protection aspects. The use of patient-related data and images must be made anonymously and with the written consent of the parties involved. Patients participating in the lectures for demonstration purposes must sign a consent form or, if necessary, be removed from the lecture transcript. A lack of personnel and technical support , uncertaA limitation of our investigation is that not all lectures in orthopaedics could be provided as podcasts and that not all lectures were provided with PDF lecture slides. A conclusion as to whether the absence of individual podcasts or lecture slides had an influence on the relevant lecture topic in the examination results was not possible due to the test setting.Furthermore, the average very good results in the final examination make it more difficult to investigate the influence of the learning materials or learning times used on the examination results. It might have been possible to find correlations between these influencing factors and the individual examination results if there had been a greater disparity.Based on the given data, another limitation lies in the fact that no exact comparison between the changes of students’ motivation to participate in a lecture was possible. The first questionnaire was answered during the facultative first lecture with possibly more interested students whereas the second and third questionnaires were taken before the compulsory examination, with all students of the semester participating. This possibly caused a bias and increased the difficulties in comparing the data. A follow-up of all questionnaires was not possible due to the anonymous data collection for the first and second questionnaires.Finally, in order to determine whether the provision of video podcasts would reduce the number of students attending the lectures, it would be desirable to count the number of attendees in the previous years of the orthopaedics lectures in order to objectify the statements made by the students.Students in the age of digitalization use a variety of learning materials and are no longer tied to classical analogue teaching methods. They are increasingly using digital media such as online lecture slides, web-based knowledge and examination platforms and online podcasts to prepare for examinations instead of traditional analogue methods, such as attending lectures or acquiring knowledge through textbooks. The use of online podcasts did not have a negative or positive impact on the test performance.The provision of video podcasts of the main lectures in orthopaedics was no reason for the majority of students not to attend the lecture. For most students, lecture podcasts were a useful supplement to attending lectures, and students praised the expansion of the teaching curriculum to include additional digital offers with positive comments in the evaluations.


We present a system consisting of two stacked chiral plasmonic nanoelements, so-called triskelia, that exhibits a high degree of circular dichroism. The optical modes arising from the interactions between the two elements are the main responsible for the dichroic signal. Their excitation in the absorption cross section is favored when the circular polarization of the light is opposite to the helicity of the system, so that an intense near-field distribution with 3D character is excited between the two triskelia, which in turn causes the dichroic response. Therefore, the stacking, in itself, provides a simple way to tune both the value of the circular dichroism, up to 60%, and its spectral distribution in the visible and near infrared range. We show how these interaction-driven modes can be controlled by finely tuning the distance and the relative twist angle between the triskelia, yielding maximum values of the dichroism at 20° and 100° for left- and right-handed circularly polarized light, respectively. Despite the three-fold symmetry of the elements, these two situations are not completely equivalent since the interplay between the handedness of the stack and the chirality of each single element breaks the symmetry between clockwise and anticlockwise rotation angles around 0°. This reveals the occurrence of clear helicity-dependent resonances. The proposed structure can be thus finely tuned to tailor the dichroic signal for applications at will, such as highly efficient helicity-sensitive surface spectroscopies or single-photon polarization detectors, among others. For a given chiroptical system, the differences in the signal of the optical functions 7 to ascertain the significance of any dichroism present in the spectra of the optical functions of a system.Chiral structures play a key role in the working mechanism of a wide variety of biological processes and biochemical interactions, and thus hold promise for several technological applications. The term “chiral” refers to structures which are not superimposable with their mirror image. Therefore, any chiral structure can be found in two different handedness formed of the same building blocks. One of the most relevant properties of chiral structures is that the two versions of the system react differently under the illumination of left-handed (LCP) and right-handed (RCP) circularly polarized light. This chiroptical activity has been extensively used in many fields, such as chemistrymentclass2pt{minim8, the manipulation of nanoparticle assemblies10 or the stacking of pseudo-planar structures12, among others. Even though planar structures can be easily manufactured by standard lithography processes13, in the recent years, 3D plasmonic structures have gained interest because of their enhanced chiral response and simple tunability, compared to their 2D counterparts16. Despite the good performance of 3D structures, their manufacture can be highly demanding and limited by practically attainable feature sizes and complex manufacturing procedures, especially if a strong CD in the visible range is desired. To address this issue, stacked 2D nanostructures made of simple elements following a multilayered design can fill in the gap as they have shown to exhibit broadband dichroic signals24. Although the twice exposure of the pattern with high alignment precision during nanofabrication makes stacked 2D nanostructures also challenging, they might be easier to manufacture when based on simple designs than 3D structures. Thus, stacked 2D structures can be broadly found in many applications related to nanophotonics27. Despite their apparent simple design, complex interactions among the plasmonic nanoelements acting as basic building blocks of these structures enable to manipulate light in a highly efficient way. For instance, the optical response of the system can be tuned by simply controlling the spatial arrangement of the building blocks in the structure.Due to the versatility of plasmonic metamaterials, several plasmonic chiral systems have been proposed in the last years in response to a growing interest in the experimental realization of such chiral nanostructures. The approaches to their manufacture comprehend the realization of three-dimensional (3D) structures28, the plasmonic nanoelements used as building block in this work has a handedness such that they are optically active in nature. This yields to the arising of additional resonances driven by the interaction between the two elements. Consequently, the CD of the structure can be controlled by the in-plane relative rotation angle (twist angle) between the basic elements with respect to the handedness of the element itself together with the distance between the elements. We therefore present a system consisting of two stacked chiral plasmonic nanoelements with three-fold rotational symmetry, so-called triskelia, providing a high degree of CD in the visible to near-infrared range that could be easily tuned in a manufacturing process.Unlike previous realizations of stacked structures29). We use an impinging plane wave along the dx-dy-dz, respectively, growing uniformly in dz up to a maximum of 25 nm out of the nearfield close to the simulation boundaries, so that convergence  is attained. The total and scattered fields are then collected to give rise to the nearfield intensity color maps and the cross-sections. All fields are normalized to the amplitude of the impinging plane wave.The simulations presented hereafter have been performed using a commercial Finite Difference Time Domain (FDTD) method providing a robust and reliable solver for Maxwell’s equations . It is worth stressing that these two geometric parameters could be easily tuned in a manufacture process. The material chosen for the study of the optical response of the system is gold owing to its well-known plasmonic properties and chemical inertness39. Numerical simulations of the absorption and scattering CS for a single triskelion with 30 nm in thickness show that the corresponding CD signals are maximized (not shown) when all the angles in Fig. Prior to the design of more complex chiral structures, it is convenient to choose a planar monomer showing some dichroism in its optical response that can be appropriate as building block of 3D chiral systems. We have chosen a monomer made up of three elements emanating from a center with three-fold rotational symmetry so that its electric polarization is not fully compatible with an even number of poles35 is known to prevent any CD in the total optical extinction. However, as shown in Fig. 33. However, when triskelia are set to form a non-planar structure, the optical properties of the whole system are expected to change drastically, enabling the existence of CD in the extinction CS.A priori, the planar nature of a single triskelion in combination with reciprocityAs an example, Fig. φ between the two triskelia in the stack. This will effectively modify the distance between the legs of the two triskelia, as well as induce a “sense of turn”35. In fact, when 37. Therefore, for those twist angles, the system only displays some differences in the absorption and scattering CS mostly around the peak at 710 nm and smaller around 1000 nm but not in the extinction CS as in the case of a single triskelion  that are always present under both circular polarizations and, more importantly, the emergence of two extra excitations with intensities which vary greatly as a function of the handedness of the circular polarization. For instance, it is found that the extra excitations in the absorption, which are clearly visible under LCP incidence at an anticlockwise φ ≤ 60° . Maximum values for the CD in the extinction CS can be found for φ = 20° (and φ = 100°) for the excitation around 1000 nm, reaching CD values up to 60%. High values of the CD can also be found in a broad range of parameters around the maximal value. In addition, remarkable CD values are also shown at the resonance in the vicinity of 710 nm. For twist angles of 30° and 90° we can observe a sharp increase in the CD. These results show that our structure presents values of the CD perfectly comparable to those of the state of the art, even outperforming similar works40.Figure see Fig. , for an see Fig. g–i. By valmost optically equivalent to that of the clockwise ones starting from 120°42 , these results put forward the occurrence of clear helicity-dependent excitations  that are manifested as enhanced absorption peaks. We would like to point out the interesting features associated with two special angles. These are the aforementioned highly symmetric case of φ = 0° that shows no CD (despite being driven by near-field interactions) and that of φ = 60°, which shows a peculiar behavior since the only element that breaks perfect symmetry is the bending angle at the midpoint of the legs of each triskelion.Since the range of anticlockwise twist angles within 0° and 60° is φ = 60°, where the CD in the extinction CS vanishes  of the main excitations in the absorption and the scattering CS occur when φ is increased or decreased from 60°. These symmetric dispersions of the absorption  and those owing to the interactions between the two triskelia in the stack  must be analyzed separately. Both kinds of excitations, exhibit spectral shifts of the corresponding CS as a function of φ, as expected for interacting systems  between them. In Sect. "ion Fig. a, d, as ons Fig. b,e for eons Fig. c,f as thA quick inspection of the CD of the absorption and scattering CS Fig. g,h reveaφ in Sect. Finally, it is worth stressing that the study of the optical response as a function of the twist angle φ are 30° and 60°  in the vicinity (2 nm above) of each triskelion are shown in Fig. 60° Fig. , and 0° Alternatively, when considering the configurations yielding no CD at all  can be gained by the near-field distributions of the modulus of the electric field in the middle plane between the two triskelia for All things considered, following the results presented in previous sections, the study of the near-field distributions in the system reveals big differences in the intensity of the evanescent field under the two polarizations of light, providing a further proof of its chiral response.To summarize, the CD in the extinction CS exhibited by the twisted stack of triskelia is determined by the arrangement of the two elements. The extra resonances yielding the dichroic signal mostly appear in the absorption CS and are not intrinsic to a single triskelion. Most of the previous work found in the literature exploits and manipulates resonances already shown by the single element used to build the chiral structure. On the contrary, our work shows that the excitations responsible for the CD in the extinction CS are arising from the interaction between the two triskelia and are not present in the single triskelion case. Moreover, they are clearly interaction-driven since they show strong tunability by adjusting both the distance between the elements and their twist angle.In addition, the helicity of the system strongly favors the excitation of the extra resonances under the illumination of one of the circular polarizations only (that opposite to the helicity of the structure) yielding near-field distributions between the two triskelia with 3D character that cause strong CD in the extinction CS. Special cases are those for 0° and 120°, for which the extra resonances show the same intensity for both RCP and LCP light (no helicity of the stack) and their contributions cancel each other in the extinction CS. As the angle increases/decreases from these values, the intensity for one polarization raises while rapidly vanishes for the opposite polarization. Thus, at an angle of 10Finally, we have shown that by finely tuning the relative distance between the two triskelia and the twist angle of the structure, total control over the CD in the extinction can be achieved, obtaining tunable values up to 60% in the visible to near-infrared range. The simplicity with which these parameters can be manipulated and finely defined through successive lithographic and thin film deposition processes makes our design of special interest for the realization of more reliable and efficient chiral plasmonic nanostructures.This work constitutes a solid contribution to the polarization-dependent manipulation of light and holds promise for applications such as highly efficient helicity-sensitive surface spectroscopies or single-photon polarization detectors.Supplementary Figures.