The combination of intraoperative CT navigation and C-arm fluoroscopy for INFIX and percutaneous TITS screw placement in the treatment of pelvic ring injury: technical note

Background The subcutaneous screw rod system, commonly known as the internal pelvic fixator (INFIX), is useful in managing unstable pelvic ring fractures. Conventional INFIX and transiliac–transsacral (TITS) screw techniques are performed using C-arm fluoroscopy. There have been problems with medical exposure and screw insertion accuracy with these techniques. This work describes new INFIX and TITS techniques using intraoperative computed tomography (CT) navigation and C-arm fluoroscopy for pelvic ring fracture. Methods A typical case is presented in this study. An 86-year-old woman suffered from an unstable pelvic ring fracture due to a fall from a height. INFIX and TITS screw fixation with intraoperative CT navigation were selected to optimize surgical invasiveness and proper implant placement. Results The patient was placed in a supine position on a Jackson table. An intraoperative CT navigation was imaged, and screws were inserted under the navigation. Postoperative X-rays and CT confirmed that the screw was inserted correctly. This technique was less invasive to the patient and had little radiation exposure to the surgeon. Rehabilitation of walking practice was started early after the surgery, and she was able to walk with the assistance of a walker by the time of transfer. Conclusions The technique employed in our case study has the cumulative advantages of safety, accuracy, and reduced radiation exposure, together with the inherent advantages of functional outcomes of previously reported INFIX and TITS screw techniques. Further experience with this approach will refine this technique to overcome its limitations and facilitate its wider use.

Software Module Development for the Parametric Generation of Truss Structure Geometry in a Two-Dimensional Setting

Introduction. Truss structures are widespread in construction due to a number of advantages, such as economy, versatility, and scalability. Accordingly, their modeling and calculation are urgent tasks in the design of building structures. Automatic solution to these problems causes an increase in design efficiency, calculation accuracy, and lower costs. The objective of the study is to examine the functionality and operation algorithm of the software module developed by the authors that generates the geometry of two-dimensional truss structures for subsequent modeling.Materials and Methods. Following the research of the widespread truss configurations, the classification of chords available in the software under consideration is given. The method of parameterizing a truss structure is provided. This method includes base geometric parameters of the structure such as dimensions, model construction rules, and additional features, as well as a comprehensive algorithm. The software is developed in JavaScript.Results. The software module has been integrated into a web application for calculating two-dimensional rod structures. To illustrate the functionality of the software, the examples of user interface are given as well as an example problem. The example includes configuration and calculation of an inclined truss structure. The results, such as support reactions and internal forces with axial force diagram, are provided.Discussion and Conclusions. Using this software module within the framework of the tool for calculating rod structures allows for the simplified process of modeling and calculating complex truss structures, design time, and resource reduction. The software module provides tools for specifying various types of structures, applying loads and assigning properties of a rod system, which makes it a useful instrument for design engineers.

Analysis of Nonlinear Static-Dynamic Deformation of Reinforced Concrete Frames in out-of-Limit States

Постановка задачи. Приводятся расчетная модель, алгоритм расчетного анализа и результаты расчета нелинейного статико-динамического деформирования железобетонных рам в запредельных состояниях, вызванных внезапным удалением одной из несущих конструкций. Результаты. Для создания численной модели режима статико-динамического нагружения конструктивной системы использован программный комплекс LS-DYNA с применением детальной 3Д-модели, реализующей явный метод конечных элементов. При проведении расчетного анализа были приняты физико-механические характеристики деформирования материалов в трех вариантах: полученные по опытным данным Г. А. Гениева, по опытным данным Н. В. Федоровой, М. Д. Медянкина при статико-динамическом одноосном режиме испытаний ограниченного числа стандартных образцов призм и по СП 385.1325800.2018. Выводы. Численным анализом статико-динамического деформирования железобетонной рамно-стержневой системы каркаса многоэтажного здания установлено, что дифференцированный учет количественного значения модуля вязкости бетона и соответственно времени и уровня статико-динамического догружения конструкции позволяет более строго определять критерии особого предельного состояния элементов железобетонных конструктивных систем зданий и сооружений. Statement of the problem. The article presents a computational model, an algorithm for computational analysis and the results of calculating the nonlinear static-dynamic deformation of reinforced concrete frames in out-of-limit states caused by the sudden removal of one of the supporting structures. Results. To design a numerical model of the static-dynamic loading mode of a structural system, the LS-DYNA software package was used that makes use of a detailed 3D model implementing an explicit finite element method. During the computational analysis, the physical and mechanical characteristics of the deformation of materials were taken in three variants: those obtained based on the experimental data by G. A. Geniev, the experimental data by N. V. Fedorova and M. D. Medyankin under the static-dynamic uniaxial testing mode of a limited number of standard samples of prisms and according to the Russian standards SP (СП) 385.1325800.2018. Conclusions. Numerical analysis of the static-dynamic deformation of the reinforced concrete frame-rod system of a multi-storey building has established that the differentiated accounting of the quantitative value of the concrete viscosity modulus and, accordingly, the time and level of static-dynamic loading of the structure allows one to identify the criteria for the special limit state of the elements of reinforced concrete structural systems of buildings and structures in a more rigid manner.

Digital models of parametric structures

Formation of parametric structure digital model are considered. Investigation was based on the analysis of the shaping evolution of the analytical surface in the form of a hyperboloid of rotation. Finite element frame represents a spatial plate-rod system has been developed during creation of the digital model. This scheme allows to study the effectiveness of constructive solutions under dynamic influence at the design stage. Dynamic characteristics of various design solutions are considered in process of choosing a rational variant of the building frame. The influence of the inclusion of outrigger floor in the model of the frame at various levels of the building are investigated. The proposed method of research and application of the possibilities of the shaping evolution allows to proceed to the modernization of BIM technologies in the design of unique buildings. Recommendations for refining the algorithm for studying parametric object digital models were developed.

Internal friction influence on the calculation results and rod system optimization under impulse action

An algorithm for calculating elastic rod systems under the action of impulse loads, using a complex model of internal friction in the material, has been developed and implemented in software. Very short (instantaneous) and extended in time impulses are considered as variants of impulse action. The importance of taking into account the vibration energy dissipation due to internal friction in the material of the structure is shown, considering impulse effects. The implemented software module is used to calculate the dynamic responses of the system in the search for the optimal solution of the control program for the selected variable parameters, target and restrictive functions. The problem of optimizing a flat frame system loaded with static and impulse loads has been posed and solved. An algorithm for finding an optimal solution is considered. Variants of dividing variable parameters into generalized groups are discussed. The minimum volume of material, spent on the structure, is taken as an optimality criterion. Analysis of the influence of the pulse duration of a given value on the calculation results without and with internal friction, as well as a comparative analysis of the optimal designs obtained without and with internal friction in the material and various tolerances for horizontal displacements. The results obtained indicate a significant effect of internal friction on the characteristics of the optimal design, especially with active movement restrictions.

Minimally Invasive Internal Fixation of Femoral Shaft Fractures—A Biomechanical Study with a Disruptive Technique

(1) Background: In polytrauma patients, femur fractures are usually stabilised by external fixation for damage control, later being treated with definitive plate or nail osteosynthesis. Screw/rod systems established in spinal surgery might be inserted for internal fixation, providing sufficient fracture stability that subsequent intervention is unnecessary. This was to be investigated biomechanically. (2) Methods: The unilaterally applied spinal internal fixator (IF) was subjected to load and deformation analysis on artificial femurs with 32-A3 fracture according to AO classification. Distance of screws to fracture and rod to cortical bone were analysed as parameters influenced surgically as stiffness and deformation of the treated fracture. In addition, the stability of another construct with a second screw/rod system was determined. The axial load in stance phase during walking was simulated. The results were compared against an established fixed-angle plate osteosynthesis (IP). (3) Results: There were no implant failures in the form of fractures, avulsions or deformations. All unilateral IF combinations were inferior to IP in terms of stability and stiffness. The bilateral construct with two screw/rod systems achieved biomechanical properties comparable to IP. 4) Conclusion: Biomechanically, a biplanar screw/rod system is suitable for definitive fracture stabilisation of the femur, despite a damage control approach.

Combined disruption of the thoracic spine and costal arch fracture: An indicator of a severe chest trauma

Background Blunt high-energy trauma increase the risk of associated thoracic and accompanying abdominal organ injuries in chest trauma. A higher overall injury severity has been shown for sternovertebral injuries caused by a flexion-compression mechanism. Literature for a hyperextension-distraction mechanism equivalent to a costal arch fracture combined with a thoracic spinal fracture is sparse. Therefore, we want to show the clinical significance of this entity. Methods A retrospective analysis of our level-one trauma center collective of severely injured patients was performed. Patients from 2013 to 2019 that involved an Injury Severity Score (ISS) ≥16 were screened for the combined thoracovertebral injury entity and analyzed concerning its accident mechanism, the injury spectrum, and the clinical course. Results The thoracovertebral injury entity is rare. Three male patients (50–65 years old) with ISS of 57, 41, and 20 could be observed from over 1000 severely injured. All patients suffered from high-energy trauma and from tearing of the thoracic vertebrae regions 7–9. The costal arch was torn in the anterior area. All cases showed a posterolateral serial rib fracture, a traumatic intercostal pulmonary hernia, and an avulsion of the diaphragm. Two patients sustained further life-threatening injuries, such as severely bleeding avulsion to the azygos vein and a rupture of the spleen. The physicians performed exploratory thoracotomy, closure of the pulmonary hernia, re-fixation of the diaphragm and angle-stable plate osteosynthesis of the fractured ribs, including the costal arch. The spine was fixed dorsally using a screw-rod system. The patients were discharged home with independent mobility and without neurological damage. Conclusions This thoracovertebral injury entity is associated with high overall injury severity and life-threatening thoracoabdominal injuries. Injuries to the costal arch can act as an indicator of severe trauma. They should be detected thorough clinical examination and assessment of the trauma CT in the soft tissue window.

Ocular Characteristics of Patients with Leber Congenital Amaurosis 6 Caused by Pathogenic RPGRIP1 Gene Variation in a Chinese Cohort

Purpose. To delineate the clinical and genetic characteristics of Chinese patients with RPGRIP1-associated Leber congenital amaurosis 6 (LCA6). Methods. After screening 352 unrelated families with clinically diagnosed RP, five LCA6 patients with RPGRIP1 variations from unrelated Chinese families were identified. Full ophthalmology examinations, including decimal best-corrected visual acuity (BCVA), fundus photography, fundus autofluorescence imaging, spectral-domain optical coherence tomography (SD-OCT), full-field electroretinography (ffERG), multifocal electroretinography (mfERG), perimetry, and flash visual evoked potential (FVEP), were performed. Target next-generation sequencing (NGS) and Sanger sequencing were performed for the five patients to identify and to validate candidate disease-causing variants. Results. Five patients were molecularly diagnosed as the LCA6 associated with RPGRIP1 variation, with typical clinical characteristics including congenital night blindness, nystagmus, and visual defect, at an early age. Interestingly, LCA6 exhibited extensive clinical heterogeneity and the changes in the morphology and function were not completely consistent in the five LCA6 patients. Case 1 showed extensive inferior-nasal retinal atrophy with a corresponding area of hypofluorescence in fundus autofluorescence, and the fundus photograph was nearly normal in cases 2 and 3. The ERG results displayed a moderately reduced rod-system response in cases 1 and 2 and a significant reduced rod-system response in case 3. Both case 4 and case 5 showed mottled pigmentation in fundi and an unrecordable rod and cone-system response in ERG. Moreover, we identified eight compound variants and one homozygous variant in the five patients with RPGRIP1. Conclusions. This is the largest report focused on the clinical electrophysiological features of patients with associated LCA6 caused by the variation in the RPGRIP1 gene in the Chinese population with an enriched phenotypic and genotypic background of LCA6 to improve future gene therapies.