Die Versorgung distaler Femurfrakturen: eine Biomechanische Studie unterschiedlicher Osteosynthesetechniken am osteoporotischen Femurmodell und am Humanknochen

Die Versorgung von osteoporotischen distalen Femurfrakturen gehört auch heute noch zu den ungelösten Problemen der Unfallchirurgie. Ziel dieser Arbeit war der biomechanische Vergleich verschiedener Implantate mit dem Hauptaugenmerk auf den distalen Verriegelungskonfigurationen. Für diese Studie wurden der T2-Standardfemurnagel (Stryker), der Suprakondyläre Nagel (SCN, Stryker) mit distaler Kondylenschraubenverriegelung, der Distale Femurnagel von Synthes (DFN) mit Spiralklingenverriegelung und die Stryker AxSOS-Platte mit winkelstabiler Verriegelung ausgewählt. Das von uns verwendete Knochenmodell bestand aus eigens hergestellten, distaler PU-Schaumkondylen. Die Osteosynthesen wurden zum einen an einer suprakondylären Fraktur ohne Gelenkbeteiligung (AO 33 A3) und zum anderen einer Fraktur mit Gelenkbeteiligung (AO 33 C2) untersucht. Die biomechanischen Tests erfolgten sowohl durch Torsions- als auch axiale Belastung. Es wurden die initiale Torsionsstabilität, die Torsionsfestigkeit, die initial-axiale Steifigkeit und die axiale Festigkeit ermittelt. In einem zweiten Testabschnitt ist der axiale Stufentest mit dem SCN und DFN an 8 Paar humanen Femora wiederholt worden, um die Übertragbarkeit der am Knochenmodell gewonnen Daten zu überprüfen. Die Ergebnisse des Torsionstests zeigten die AxSOS-Platte als das Implantat mit den stabilsten Osteosynthesen. Im axialen Stufentest erreichte der SCN die signifikant höchste axiale Steifigkeit und die größte Festigkeit. Die AxSOS-Platte erwies sich als die Versorgung mit der geringsten axialen Steifigkeit unabhängig vom Frakturtyp. Die Untersuchungen am humanen Knochen zeigten in Analogie zu den Ergebnissen am synthetischen Knochenmodell eine signifikant höhere axiale Steifigkeit und Festigkeit des SCN im Vergleich zum DFN. Die Stabilität der Versorgung einer distalen Femurfraktur durch einen Marknagel hängt stark der Art der distalen Verriegelung ab. Unsere Arbeit belegt die Vorrangstellung eines neuen Systems, des SCN, über alle anderen untersuchten Implantate sowohl bei der Versorgung der A- als auch der C-Fraktur

Long-term stability of angle-stable versus conventional locked intramedullary nails in distal tibia fractures

Background: In the last years intramedullary nailing has become the treatment of choice for most displaced diaphyseal tibia fractures. In contrast intramedullary nailing of distal tibia fractures is accompanied by problems like decreased biomechanical stability. Nevertheless the indications for intramedullary nailing have been extended to include even more distal fractures. The purpose of this study was to compare long-term mechanical characteristics of angle-stable versus conventional locked intramedullary nails in the treatment of unstable distal tibia fractures. Therefore, the effect of time on the mechanical properties of biodegradable sleeves was assessed. Methods: 8 pairs of fresh, frozen porcine tibiae were used. The expert tibial nail (Synthes) was equipped with either three conventional locking screws (CL) or the angle-stable locking system (AS), consisting of a special ASLS screw and a biodegradable sleeve. Biomechanical testing included torsional and axial loading at different time-points over 12 weeks. Results: The AS group showed a significantly higher torsional stiffness at all time-points (at least 60%) compared to the CL group (p 0.05). For axial stiffness and range of motion significant differences were found in the AS group. Conclusions: The angle-stable locking system (ASLS) with the biodegradable sleeve provides significantly higher long-term stability. Especially the differences determined under torsional loading in this study may have clinical relevance. The ASLS permits the potential to decrease complications like secondary loss of reduction and mal-/non-union.

Implant augmentation: Adding bone cement to improve the treatment of osteoporotic distal femur fractures:A biomechanical study using human cadaver bones

The increasing problems in the field of osteoporotic fracture fixation results in specialized implants as well as new operation methods, for example, implant augmentation with bone cement. The aim of this study was to determine the biomechanical impact of augmentation in the treatment of osteoporotic distal femur fractures. Seven pairs of osteoporotic fresh frozen distal femora were randomly assigned to either an augmented or nonaugmented group. In both groups, an Orthopaedic Trauma Association 33 A3 fractures was fixed using the locking compression plate distal femur and cannulated and perforated screws. In the augmented group, additionally, 1 mL of polymethylmethacrylate cement was injected through the screw. Prior to mechanical testing, bone mineral density (BMD) and local bone strength were determined. Mechanical testing was performed by cyclic axial loading (100 N to 750 N + 0.05N/cycle) using a servo-hydraulic testing machine. As a result, the BMD as well as the axial stiffness did not significantly differ between the groups. The number of cycles to failure was significantly higher in the augmented group with the BMD as a significant covariate. In conclusion, cement augmentation can significantly improve implant anchorage in plating of osteoporotic distal femur fractures

An unusual cause of ankle pain: fracture of a talocalcaneal coalition as a differential diagnosis in an acute ankle sprain: a case report and literature review

Background: The acute ankle sprain is one of the most common injuries seen in trauma departments. Ankle sprains have an incidence of about one injury per 10 000 people a day. In contrast tarsal coalition is a rare condition occurring in not more than one percent of the population. Case presentation: We present the case of a 23 year old male patient with pain and local swelling after an acute ankle sprain. Initial clinical and radiological examination showed no pathologies. Due to prolonged pain, swelling and the inability of the patient to weight bear one week after trauma further diagnostics was performed. Imaging studies (MRI and CT) revealed a fracture of a talocalcaneal coalition. To the knowledge of the authors no fracture of a coalition was reported so far. Conclusion: This report highlights the presentation of symptomatic coalitions following trauma and furthermore, it points out the difficulties in the diagnosis and treatment of a rare entity after a common injury. A diagnostic algorithm has been developed to ensure not to miss a severe injury.<br

Bone Regeneration: A Novel Osteoinductive Function of Spongostan by the Interplay between Its Nano- and Microtopography.

Vordemvenne T, Wähnert D, Koettnitz J, et al. Bone Regeneration: A Novel Osteoinductive Function of Spongostan by the Interplay between Its Nano- and Microtopography. Cells. 2020;9(3): 654.Scaffold materials for bone regeneration are crucial for supporting endogenous healing after accidents, infections, or tumor resection. Although beneficial impacts of microtopological or nanotopological cues in scaffold topography are commonly acknowledged, less consideration is given to the interplay between the microscale and nanoscale. Here, micropores with a 60.66 ± 24.48 m diameter ordered by closely packed collagen fibers are identified in pre-wetted Spongostan, a clinically-approved collagen sponge. On a nanoscale level, a corrugated surface of the collagen sponge is observable, leading to the presence of 32.97 ± 1.41 nm pores. This distinct micro- and nanotopography is shown to be solely sufficient for guiding osteogenic differentiation of human stem cells in vitro. Transplantation of Spongostan into a critical-size calvarial rat bone defect further leads to fast regeneration of the lesion. However, masking the micro- and nanotopographical cues using SiO2 nanoparticles prevents bone regeneration in vivo. Therefore, we demonstrate that the identified micropores allow migration of stem cells, which are further driven towards osteogenic differentiation by scaffold nanotopography. The present findings emphasize the necessity of considering both micro- and nanotopographical cues to guide intramembranous ossification, and might provide an optimal cell- and growth-factor-free scaffold for bone regeneration in clinical settings

Temperature influence on DXA measurements: bone mineral density acquisition in frozen and thawed human femora

<p>Abstract</p> <p>Background</p> <p>Determining bone mineral density (BMD) with dual-energy x-ray absorptiometry (DXA) is an established and widely used method that is also applied prior to biomechanical testing. However, DXA is affected by a number of factors. In order to delay decompositional processes, human specimens for biomechanical studies are usually stored at about -20°C; similarly, bone mineral density measurements are usually performed in the frozen state. The aim of our study was to investigate the influence of bone temperature on the measured bone mineral density.</p> <p>Methods</p> <p>Using DXA, bone mineral density measurements were taken in 19 fresh-frozen human femora, in the frozen and the thawed state. Water was used to mimic the missing soft tissue around the specimens. Measurements were taken with the specimens in standardized internal rotation. Total-BMD and single-BMD values of different regions of interest were used for evaluation.</p> <p>Results</p> <p>Fourteen of the 19 specimens showed a decrease in BMD after thawing. The measured total-BMD of the frozen specimens was significantly (1.4%) higher than the measured BMD of the thawed specimens.</p> <p>Conclusion</p> <p>Based on our findings we recommend that the measurement of bone density, for example prior to biomechanical testing, should be standardized to thawed or frozen specimens. Temperature should not be changed during measurements. When using score systems for data interpretation (e.g. T- or Z-score), BMD measurements should be performed only on thawed specimens.</p

A Role for NF-κB in Organ Specific Cancer and Cancer Stem Cells

Kaltschmidt C, Banz-Jansen C, Benhidjeb T, et al. A Role for NF-κB in Organ Specific Cancer and Cancer Stem Cells. Cancers. 2019;11(5): 655.Cancer stem cells (CSCs) account for tumor initiation, invasiveness, metastasis, and recurrence in a broad range of human cancers. Although being a key player in cancer development and progression by stimulating proliferation and metastasis and preventing apoptosis, the role of the transcription factor NF-κB in cancer stem cells is still underestimated. In the present review, we will evaluate the role of NF-κB in CSCs of glioblastoma multiforme, ovarian cancer, multiple myeloma, lung cancer, colon cancer, prostate cancer, as well as cancer of the bone. Next to summarizing current knowledge regarding the presence and contribution of CSCs to the respective types of cancer, we will emphasize NF-κB-mediated signaling pathways directly involved in maintaining characteristics of cancer stem cells associated to tumor progression. Here, we will also focus on the status of NF-κB-activity predominantly in CSC populations and the tumor mass. Genetic alterations leading to NF-κB activity in glioblastoma, ependymoma, and multiple myeloma will be discussed

Instability of the posterior pelvic ring: introduction of innovative implants

Grüneweller N, Wähnert D, Vordemvenne T. Instability of the posterior pelvic ring: introduction of innovative implants. Journal of Orthopaedic Surgery and Research. 2021;16(1):625.BACKGROUND: Increasing numbers of posterior pelvic ring fractures, especially in elderly patients, demonstrate the need for soft tissue protecting surgical techniques. Standard of care is iliosacral screw osteosynthesis. This type of osteosynthesis has its limitations especially in patients with reduced bone properties. Therefore, the development of new and straightforward surgical techniques and implant designs is favorable.; METHODS: Introducing this modular system for the posterior pelvic ring, known complications of iliosacral screw osteosynthesis, such as implant loosening and malpositioning may be reduced, due to innovative mechanical characteristics.; RESULTS: The shown cases demonstrate the potential benefits of the system with a wide range of treatment options due to its modularity.; CONCLUSION: The modular implant system presented here can significantly facilitate and improve the stabilization of posterior pelvic ring instabilities. © 2021. The Author(s)

AED drones on the rise? : Use of drones to improve public access defibrillation

Thies K-C, Jansen G, Wähnert D. Kommt die Defi-Drohne? Einsatz von Drohnen zur Verbesserung der Frühdefibrillationsrate. Anaesthesiologie. 2022.BACKGROUND: The poor availability of automatic external defibrillators (AED) and the modest knowledge of lay persons in handling these devices has led to an insufficient spread of public access defibrillation in Germany.; OBJECTIVE: This article examines whether the automated deployment of AED drones to out-of-hospital cardiac arrest can help to remedy this situation.; METHODS: Narrative literature review, evaluation of statistics, analysis of relevant media reports, and discussion of key research.; RESULTS: The present investigations are mainly located in the experimental field and demonstrate the feasibility and safety of drone use, as well as shorter times to first defibrillation, which is confirmed by initial clinical studies. Mathematical models also indicate cost-effectiveness of airborne AED delivery compared to ground dispatch. Integration into the chain of survival appears to be possible but adaptations to existing emergency medical service structures and close cooperation with regional first responder and AED schemes as well as local authorities is required to optimise patient benefit and efficiency.; CONCLUSION: The use of AED drones could probably contribute to improving public access defibrillation in Germany. This applies to both rural and urban regions. The technological requirements are met but flight regulations still have to be amended. In order to explore the full potential of this novel technology, further field trials are required to achieve smooth integration into existing emergency medical services. © 2022. The Author(s).Hintergrund Der Mangel an automatischen externen Defibrillatoren (AED) und die fehlende Kenntnis von Ersthelfern im Umgang mit diesen Geräten haben in Deutschland zu einer ungenügenden Verbreitung der Public-Access-Defibrillation geführt. Fragestellung Dieser Artikel untersucht, inwieweit die automatisierte Zuführung von AED bei außerklinischem Herz-Kreislauf-Stillstand mithilfe von Drohnen hier Abhilfe schaffen kann. Material und Methodik Narrative Literaturübersicht, Auswertung von Statistiken, Analyse relevanter Medienmeldungen und Diskussion von Grundlagenarbeiten. Ergebnisse Die vorliegenden Untersuchungen sind überwiegend im experimentellen Bereich angesiedelt und belegen die Machbarkeit und die Sicherheit des Drohneneinsatzes sowie eine Verkürzung der Zeit bis zur Erstdefibrillation. Erste klinische Studien bestätigen dies. Schlussfolgerung Defi-Drohnen könnten wahrscheinlich zur Verbesserung der Frühdefibrillationrate in Deutschland beitragen. Dies gilt sowohl für den ländlichen als auch den urbanen Raum. Die technologischen Voraussetzungen sind gegeben, die flugrechtlichen Bedingungen müssten allerdings noch angepasst werden. Um das volle Potenzial der neuen Technologie auszuloten, sind weitere Feldversuche erforderlich

Local heat generation during screw insertion into diaphyseal bone: a biomechanical study on different conditions (e.g. screw type, material, mode of insertion).

Paul B, Frank A, Raschke MJ, Wähnert D. Local heat generation during screw insertion into diaphyseal bone: a biomechanical study on different conditions (e.g. screw type, material, mode of insertion). BMC Musculoskeletal Disorders . 2021;22(1): 841.BACKGROUND: The implantation of screws is a standard procedure in musculoskeletal surgery. Heat can induce thermal osteonecrosis, damage the bone and lead to secondary problems like implant loosening and secondary fractures. The aim of this study was to investigate whether screw insertion generates temperatures that can cause osteonecrosis.; METHODS: We measured the temperature of twenty human femur diaphysis in a total of 120 measurements, while screws of different material (stainless steel and titanium alloy) and different design (locking and cortex screw) were inserted in three different screwing modes (manual vs. machine screwing at full and reduced rotational speed) with 6 thermocouples (3 cis and 3 trans cortex). Each was placed at a depth of 2mm with a distance of 1.5mm from the outer surface of the screw.; RESULTS: The screw design (cortical > locking), the site of measurement (trans-cortex > cis-cortex) and the type of screw insertion (hand insertion > machine insertion) have an influence on the increase in bone temperature. The screw material (steel > titanium), the site of measurement (trans-cortex > cis-cortex) and the type of screw insertion (machine insertion > hand insertion) have an influence on the time needed to cool below critical temperature values. The combination of the two parameters (maximum temperature and cooling time), which is particularly critical for osteonecrosis, is found only at the trans-cortex.; CONCLUSION: Inserting a screw hast the potential to increase the temperature of the surrounding bone tissue above critical values and therefore can induce osteonecrosis. The trans-cortex is the critical area for the development of temperatures above the osteonecrosis threshold, making effective cooling by irrigation difficult. It would be conceivable to cool the borehole with cold saline solution before inserting the screw or to cool the screw in cold saline solution. If possible, insertion by hand should be considered. © 2021. The Author(s)