[The effect of mobile air filter systems on aerosol concentrations in large volume scenarios against the background of the risk of infection of COVID-19. Can classroom teaching be resumed?] / Der Effekt von mobilen Luftfiltersystemen auf die Aerosolbelastung in Großraumszenarien vor dem Hintergrund des Infektionsrisikos der COVID-19-Erkrankung. Kann die Präsenzlehre wieder aufgenommen werden?

BACKGROUND: As a consequence of the corona pandemic, universities nationwide had stopped classroom teaching by the start of the summer semester 2020. As part of the second lockdown, in many states schools and day care centers were also closed or reduced to a minimum. In this context the effect of room air filters has already been discussed multiple times; however, mobile devices for air filtration are currently not recommended by the German Federal Environment Agency. The following investigation shows the real effects of mobile air filters on aerosol concentrations when used in lecture theaters, canteens or school learning centers. METHODS: The effects of a mobile air purifier (DEMA-airtech, Stuttgart, Germany) were measured in three large rooms (a lecture theater, a company canteen and a learning center of a grammar school). Aerosol and carbon dioxide concentrations were determined with devices from the company Palas (Karlsruhe, Germany). RESULTS: All three scenarios showed a relevant and permanent decrease in aerosol concentrations through the use of air filters. The effect partly even surpassed the effectiveness of simple ventilation by opening the windows. CONCLUSION: In addition to social distancing and wearing highly efficient face masks, the use air filters is recommended. This measure could enable classroom teaching to be resumed.

[The new treatment procedures of the DGUV from the perspective of an injury type procedure (VAV) clinic]. / Die neuen Heilverfahren der DGUV aus der Sicht einer VAV-Klinik.

The new treatment procedures of the German Statutory Accident Insurance (DGUV) have ramifications for the injury type procedure clinics (VAV) from medical, economic and structural aspects. Whereas the latter can be assessed as positive, the medical and economical aspects are perceived as being negative. Problems arise from the partially unclear formulation of the injury type catalogue, which results in unpleasant negotiations with the occupational insurance associations with respect to financial remuneration for services rendered. Furthermore, the medical competence of the VAV clinics will be reduced by the preset specifications of the VAV catalogue, which opens up an additional field of tension between medical treatment, fulfillment of the obligatory training and acquisition of personnel as well as the continually increasing economic pressure. From the perspective of the author, the relinquence of medical competence imposed by the regulations of the new VAV catalogue is "throwing the baby out with the bathwater" because many VAV clinics nationwide also partially have competence in the severe injury type procedure (SAV). A concrete "competence-based approval" for the individual areas of the VAV procedure would be sensible and would maintain the comprehensive care of insured persons and also increase or strengthen the willingness of participating VAV hospitals for unconditional implementation of the new VAV procedure.

[Comparing effectivity of VAC therapy for treatment of infections following arthroplasty or soft-tissue surgery]. / Vergleich der Effektivität der VAC-Therapie bei der Behandlung von Prothesen- und Weichteilinfektionen.

BACKGROUND: Although vacuum-assisted wound closure (VAC) has been developed into a standard technique in septic surgery, reliable data about the efficacy of the treatment are still lacking. PATIENTS: Postoperative infections after arthroplasty or soft-tissue surgery were identified using a prospective database for complications (Critical Incidence Reporting System) which was retrospectively supplemented with items for evaluation of VAC therapy. Eradication success of infection was analysed considering epidemiological parameters, course of treatment, and characteristics of causing bacterial strains. Furthermore, serological C-reactive protein (CRP) concentrations were evaluated for diagnostic and prognostic reliability. RESULTS: 92 patients with an average age of 60 ± 4 years were included in the study. Patients with soft tissue infections (STI, n = 53) were statistically significant younger compared to patients with infections following arthroplasty (AI, n = 39) (53 ± 6 vs. 70 ± 4 years; p < 0.001), but the probability for eradication success was not dependent on age. Mortality was 9-fold higher in the AI group (p < 0.01). Patients with infected endoprostheses were longer treated on intensive care units (6.1 ± 8.4 vs. 3.5 ± 6.5 days; p < 0.01), but there was no statistically significant association to eradication success. Probability for eradication of infection was with 81 % statistically significant higher in the STI group compared to 38 % in the AI group (p < 0.001). Early infections in the AI group were associated with a better healing success when compared to chronic infections (p < 0.05). The same correlation could be shown for the removal of implant (p < 0.0001). Aerobic fermenting bacteria were less effectively eradicated than anaerobic germs following soft-tissue infections (p < 0.01). In cases of osteomyelitis following soft-tissue infection, the probability for eradication of infection was impaired (p < 0.001). Kind and quality of final wound closure in the STI group were statistically significantly associated with eradication success (p < 0.001). There was no critical value concerning the number of revisions until healing of infection was reached. CRP values were higher in the AI group and associated with the prognosis (p < 0.05). CONCLUSION: Probability of eradication success using VAC therapy is higher after soft-tissue infections compared to infections following arthroplasty. Accordingly, mortality is higher in this group. Chronic courses have worse chances for healing in both groups. For serological CRP values a prognostic relevance could be shown.

New selective endoscopic sacral nerve root stimulation--an advance in the treatment of fecal incontinence.

BACKGROUND: Fecal incontinence (FI) is a major part of illness and physical discomfort in the general population. Since the 1990s, sacral nerve stimulation has been well established in the treatment of neurogenic FI. The precise placement of the electrode is crucial for the success of the procedure. Eighty percent of the patients benefit from permanent treatment, but in 10-20% of the patients tested electrode placement proves impossible due to anatomical variations of the sacral foramina. In this study, we describe the technical requirements and a new method of electrode placement with reference to the anatomical (bone) landmarks in an animal model. METHODS: With a small endoscope (Verres needle), we accessed the perirectal space to identify the nervous structures. A stimulated sphincter EMG was obtained for the experimental animals and muscle action potential (MAP/M-wave), latency time [ms], and the amplitude of the motor response [µV] were recorded. Electrodes were placed, the animals killed and dissected leaving the pelvic cavity untouched. The specimens were examined in a magnetic resonance scanner and in a multi-slice computed tomography scanner to detect the electrode material and possible surgical complications. After that the specimens were dissected. KEY RESULTS: In all eight cases in the four animals tested, we were able to stimulate the sacral nerve as demonstrated by the EMG findings. No major surgical complications were observed for the procedure. CONCLUSIONS & INFERENCES: Endoscopic sacral nerve root stimulation is a safe and effective method for delivering stimulation material in the pelvis of the sheep. It is a promising procedure to be tested in humans.

Percutaneous iliosacral screw insertion: malpositioning and revision rate of screws with regards to application technique (navigated vs. Conventional).

BACKGROUND: Conventional percutaneous iliosacral screw placement in pelvic surgery is considered to be a highly demanding operative technique with a high rate of screw malpositions, which may be associated with the risk of neurologic damage or inefficient stability. In the conventional technique, the correct entry point for the screw and the small target corridor for the iliosacral screw may be difficult to visualize using an image intensifier. We tried to find out in this study whether the positioning of percutaneous screw implantations could be optimized by evaluating the rate and grade of malpositions and whether the needed revisions could be reduced by using computer navigation and three-dimensional (3D) image intensifier. METHODS: A group of 54 patients with 63 screws implanted using computer navigation was compared with 87 patients with 131 screws implanted using the conventional fluoroscopic technique. The exact screw position was controlled in a postoperative computed tomography scan, and the grade of malposition of every screw was investigated and compared. RESULTS: A complete intraosseous screw position was found in 42% of cases using the conventional technique and was significantly less compared with 81% using a 3D image intensifier in combination with a navigation system. Moreover, the revision rate of 1.6% was significantly less in the navigated group compared with 19% in the conventional group. CONCLUSIONS: The results indicate that 3D-computer navigation of the percutaneous iliosacral screw insertion can facilitate surgical performance in respect to reducing screw malposition and revision rates.

Dissection of RAS downstream pathways in melanomagenesis: a role for Ral in transformation.

Cutaneous malignant melanoma is considered one of the most deadly human cancers, based on both its penchant for metastatic spread and its typical resistance to currently available therapy. Long known to harbor oncogenic NRAS mutations, melanomas were more recently reported to be frequent bearers of activating mutations in BRAF, one of the effectors situated downstream of wild-type NRAS. NRAS and BRAF mutations are rarely found in the same melanoma, suggesting that they may possess important overlapping oncogenic activities. Here, we compare and contrast the oncogenic roles of the three major NRas downstream effectors, Raf, phosphatidylinositol 3-kinase (PI3K) and Ral guanine exchange factor (RalGEF), using genetically engineered Arf-deficient immortalized mouse melanocytes as a model system. Although no single downstream pathway could recapitulate all of the consequences of oncogenic NRas expression, our data indicate a prominent role for BRaf and PI3K in melanocyte senescence and invasiveness, respectively. More surprisingly, we discovered that constitutive RalGEF activation had a major impact on several malignant phenotypes, particularly anchorage-independent growth, indicating that this often overlooked pathway should be more carefully evaluated as a possible therapeutic target.

[Variability of the screw position after 3D-navigated sacroiliac screw fixation. Influence of the surgeon's experience with the navigation technique]. / Variabilität der Schraubenlage bei 3D-navigierter Sakrumverschraubung. Einfluss der operateurspezifischen Navigationserfahrung.

BACKGROUND: The precision of sacroiliac screw placement can be improved with the use of navigation techniques. The purpose of this study was to evaluate the accuracy of 3D-navigated sacroiliac screw positioning in relation to the surgeon's experience with the navigation technique. PATIENTS AND METHODS: A consecutive series of 3D-navigated sacroiliac screw placements were prospectively evaluated between December 2005 and February 2008. Postoperatively the precision of screw placement was analyzed in relation to the surgeon's navigation experience with a CT-scan using the criteria of Smith. RESULTS: A total of 37 screws were implanted by 7 surgeons in 33 patients. In the group of surgeons with less experience in navigation techniques two cases of malpositioning led to revision of the screws. No screws which were implanted or assisted by surgeons experienced in navigation needed to be revised. There was no significant difference in the malposition rate. CONCLUSION: In the clinical setup a malpositioning of sacroiliac screws is possible even with the use of 3D navigation. One reason may be a low level of navigation experience of the surgeon in combination with low experience in the conventional technique. Therefore even in navigation-based placement of sacroiliac screws the malpositioning rate is dependent on the surgeon's experience with the navigation technique. The correct placement of the screws should be controlled intraoperatively using the 3D image intensifier.

Evaluation of Singh index for assessment of osteoporosis using digital radiography.

Evaluation of Singh index (SI) as a simple means for estimating bone mass on radiographs has been subject of numerous studies. All of these studies used plain film radiographs for assessment of SI. Digital radiography may improve validity and reliability of SI assessment. Aim of this study was to evaluate SI gradings assessed on digital radiographs. Digital pelvic radiographs of 100 patients were graded using SI by five independent observers (two radiologists, three traumatologists) blinded to dual energy X-ray absorptiometry (DXA) results and re-graded by all observers for assessment of intraobserver agreement. SI was correlated with DXA measurements and after grouping the patients according to World Health Organisation (WHO) criteria (osteoporosis, osteopenia, normal). Logistic regression analysis was performed in order to identify influential parameters on the SI grading process. Mean intraobserver agreement was 0.648+/-0.18 (Kendall's Tau) and 0.43+/-0.28 (kappa). Mean interobserver agreement was 0.488+/-0.193 (Kendall's Tau) and 0.199+/-0.248 (kappa). Mean correlation between SI and trochanteric BMD and T scores was 0.219+/-0.04 and 0.210+/-0.05 (Spearman's coefficient). Only one observer (senior radiologist) reached the significance level after grouping the patients' DXA results according to WHO criteria and correlating the results with SI gradings. Logistic regression analysis revealed a significant influence of trochanteric T score in two observers while other variable parameters failed to reach the significance level. Even though we found reasonable intraobserver agreement assessment of SI is highly subjective and interobserver agreement is generally poor. Moreover, using digital radiography could not improve correlation with DXA measurements.

[Early clinical outcome after navigated total knee arthroplasty. Comparison with conventional implantation in TKA: a controlled and prospective analysis]. / Klinische und radiologische Ergebnisse nach navigierter Knieendoprothetik. Analyse einer kontrollierten und prospektiven Studie im Vergleich zur konventionellen Implantationstechnik.

BACKGROUND: Navigated implantation of total knee prostheses has become more and more popular within the last decade in orthopaedic surgery. Although improved alignment after navigated knee surgery has been reported previously in the literature, only a few studies meet the criteria of a level-1 evidence-based medicine study. We present the results of a controlled and prospective study comparing early clinical outcomes after computer-assisted versus conventional implantation in total knee arthroplasty (TKA). METHODS: Within a 15-month period, all patients admitted for primary TKA were followed prospectively. Each patient was evaluated using the Knee Society Score (KSS) preoperatively, 10 days after surgery, and 3 months after surgery. The patients were divided into two groups, and the implantation technique altered between the two treatment options: each conventional implantation was strictly followed by a computer-assisted procedure and vice versa. RESULTS: From March 2003 to June 2004, we did 34 computer-assisted (group A) and 35 conventional knee arthroplasties (group B) in 62 patients. There was no difference in the preoperative status of the patients. Surgeries in group A took significantly longer than in group B. The average deviation from correct alignment was significantly reduced in group A. 66 of 69 of the TKAs were available for follow-up examinations after 10 days and after 3 months. No significant differences were found in the overall KSS scores or in the subgroups. CONCLUSIONS: The intraoperative use of a computer-assisted navigation system during implantation of a total knee prosthesis reduced the average varus/valgus deviation from the anatomical long leg axis. A disadvantage of the computer-assisted surgical procedure may be the longer operating time. Long-term follow-up of the presented data is needed in order to show whether the improved average alignment is advantageous for patients and/or results in a longer service life of the TKA.

[Traumatic atlanto-occipital dislocation as part of a complex cervical spine injury. Case report in a 12-year-old girl]. / Traumatische atlantookzipitale Dissoziation im Rahmen einer Komplexverletzung der HWS. Fallbeschreibung bei einem 12-jährigen Kind.

Traumatic atlanto-occipital dislocation (AOD) appears to be an unusual and almost universally fatal injury. Although AOD is the cause of death in about 10% of fatal cervical spine injuries an increasing number of reports document cases of survival following this injury. Improved pre-hospital and in-hospital emergency care according to ATLS guidelines that include early cervical spine stabilization, effective diagnosis because of improved imaging after trauma including whole body multislice CT followed by expeditious reposition and adequate immobilization are reasons for this phenomenon. We report the case of a 12-year-old girl surviving an AOD accompanied by a distraction injury C6/7 with unilateral fixed spinal luxation. After a primary attempt at closed reduction and external stabilization with a halo vest, the injury was treated by a navigated dorsal spondylodesis C0-C1 using the CerviFix rod system and open reposition of the remaining subluxation C6/7 with laminar hooks. The literature was reviewed for diagnostic possibilities, management and prognosis of AOD.

Monteggia fractures in adults: long-term results and prognostic factors.

The objective of this retrospective study was to correlate the Bado and Jupiter classifications with long-term results after operative treatment of Monteggia fractures in adults and to determine prognostic factors for functional outcome. Of 63 adult patients who sustained a Monteggia fracture in a ten-year period, 47 were available for follow-up after a mean time of 8.4 years (5 to 14). According to the Broberg and Morrey elbow scale, 22 patients (47%) had excellent, 12 (26%) good, nine (19%) fair and four (8%) poor results at the last follow-up. A total of 12 patients (26%) needed a second operation within 12 months of the initial operation. The mean Broberg and Morrey score was 87.2 (45 to 100) and the mean DASH score was 17.4 (0 to 70). There was a significant correlation between the two scores (p = 0.01). The following factors were found to be correlated with a poor clinical outcome: Bado type II fracture, Jupiter type IIa fracture, fracture of the radial head, coronoid fracture, and complications requiring further surgery. Bado type II Monteggia fractures, and within this group, Jupiter type IIa fractures, are frequently associated with fractures of the radial head and the coronoid process, and should be considered as negative prognostic factors for functional long-term outcome. Patients with these types of fracture should be informed about the potential risk of functional deficits and the possible need for further surgery.

Endoscopic controlled intramedullary fracture reduction. A case report about closed fracture reduction under visual control.

Intramedullary bone endoscopy (IBE) was introduced as a new endoscopic technique in the year 2002 to achieve and manipulate the medullary canal of long bone under direct visual control. We report on a patient with a proximal femur fracture, where the new technique of IBE was used for intramedullary fracture reduction under visual control for the first time. Thus, the intraoperative use of an image intensifier was reduced.

Subchondral and trabecular bone remodeling in canine experimental osteoarthritis.

INTRODUCTION: We wanted to test the hypothesis that quality changes occur in early-stage arthritic subchondral cancellous bone after acute subchondral damage. So far, not much attention has been paid to changes of the subchondral bone after traumatic subchondral lesions. MATERIALS AND METHODS: With an established animal model, we produced pure subchondral damage without initial affection of the articular cartilage in 12 Beagle dogs under MRI and histological control. We utilized bone histomorphometry to evaluate bone turnover, its structure and the articular cartilage 6 months after the initial damage. RESULTS: On follow-up, bone remodelling was indicated, e.g. by a significant increase in the trabecular bone volume and thickness, osteoblast number and osteoid surface and a decrease in the trabecular number in all 12 samples. Several other parameters showed a tendency, e.g. osteoblast surface and osteoclast number. Cartilage analysis showed degenerative changes in ten of 12 samples that had not shown any evidence of damage during the initial examination. DISCUSSION: Our investigation indicates a significant deterioration in the architecture of the cancellous bone with degenerative changes of the overlying articular cartilage after subchondral lesions, which change the mechanical properties.

[Intramedullary bone endoscopy. First clinical application of a novel endoscopic technique]. / Intramedulläre Knochenendoskopie. Erste klinische Anwendung einer neuen endoskopischen Technik.

After successfully testing the new technique of IBE (intramedullary bone endoscopy) in vitro, we present the first clinical applications of the new endoscopic method. In two selected cases (cement removal in revision joint arthroplasty/complication management after intramedullary loss of a reamer) the technique of IBE was performed in vivo for the first time. Removal of cement under endoscopic guidance and salvage of the lost reamer was easily possible using the special endoscopic tools. With the new technique of IBE, endoscopic intramedullary manipulation is easily possible in vivo.

[CT analysis of leg alignment after conventional vs. navigated knee prosthesis implantation. Initial results of a controlled, prospective and randomized study]. / CT-Analyse der Beinachse nach konventioneller vs. navigierter Knieendoprothese. Erste Ergebnisse einer kontrollierten, prospektiven und randomisierten Studie.

INTRODUCTION: Correct alignment of the leg is one of the significant factors for the outcome after TKA. Previous studies have shown that the use of a navigation system can improve the alignment. However, for the positioning of the femoral component no validated data are available. This article presents the first results of a controlled, prospective and randomised trial comparing navigation versus free-hand implantation in TKA with special reference to the rotation of the femoral component. METHODS: Since January 2003, all patients with primary arthrosis of the knee admitted to our hospital for TKA have been followed prospectively. For this first analysis, data were collected over a period of 5 months. Apart from the usual clinical evaluations, all patients had CT of the leg prior to the operation and 1 week postoperatively. Measurement of axis and rotation was performed by staff members of the X-ray department who had no knowledge of the operation technique (navigation vs. free-hand). RESULTS: Twenty five sets of CT scans have been analysed, from 12 navigated operations and 13 freehand procedures. All 12 of the navigated knees were within the interval of +/-3 degrees varus/valgus deviation, but only 8 of the 13 non-navigated knees met this criteria. The analysis of the rotation position of the femoral component revealed no difference between the two groups. CONCLUSION: By using an intraoperative navigation system, the accuracy of the alignment in TKA can be improved. Long-term studies will have to be carried out to verify whether this will lead to a lasting benefit for the patient. Concerning the rotation position of the femoral implant, no conclusion can be made regarding the recommended rotation position at this point of the study.

[Intramedullary bone endoscopy (IBE). First results of experimental intramedullary endoscopy of long bone]. / Intramedulläre Knochenendoskopie (IBE) Erste experimentelle Ergebnisse der Endoskopie des langen Röhrenknochens.

INTRODUCTION: Intramedullary preparation and endoscopy of long bone is not mentioned in literature. We present our first results of experimental intramedullary endoscopy of long bone. METHODS: Experimental tests were performed at 4 corpse bones (twice tibia, twice femur). RESULTS: Intramedullary endoscopy and preparation was possible in all cases. A good view for inspection of the medullary canal was achieved by using the endoscope (Wolf GmbH, Germany). CONCLUSION: Endoscopic preparation and intramedullary endoscopy in the long bone ist possible. By using the endoscopic tools, a "neocavum" for endoscopic manipulation could easily be created.