Biomechanical analysis of the cervical spine segment as a method for studying the functional and dynamic anatomy of the human neck

BACKGROUND

Traditionally, dynamic and functional anatomy, in particular the dynamic anatomy of the neck, is studied on cadaveric material. However, the development of in vivo visualization technologies and in silico modeling has made it possible to expand these possibilities. Despite significant progress in the study of dynamic and functional anatomy of the neck by means of in silico methods, the issues of validating the developed models and taking into account the pronounced nonlinearity of soft tissues as well as local anisotropy remain open. The aim of this study was to develop a virtual dynamic anatomical model of the human neck and reproduce the dynamic processes in the cervical spine from this model using the finite element method.

MATERIALS AND METHODS

Reverse engineering was used to generate a dynamic anatomical model of the neck from CT data (both male, 24 and 22 years old). Two segments of the cervical spine (C3-C5, C2-T1) were isolated from the resulting model for finite element analysis. Finite element mesh generation and contact interactions were performed using the HyperMesh software (Altair Engineering Inc, Troy, Michigan, USA). The anisotropic hyperelastic Holzapfel-Gasser-Ogden model was used to describe the material behavior of the fibrous rings of the disc. Material modeling and finite element analysis were performed using Abaqus CAE 6.14 software (Simulia, Johnston, Rhode Island, USA).

RESULTS

A technique for creating a virtual dynamic anatomical model of the neck was elaborated and implemented. The model includes 79 major anatomical structures of the neck segmented from radiological data. A finite element analysis of the cervical spine was performed. The results of finite element analysis of the C3-C5 segment under axial load were compared with in vitro data. The proposed model shows nonlinear deformation of the disc under static loading; the model predicted displacement values agree well with the experimental ones. The displacement of the С3-С5 central vertebra with an axial load of 800 N reaches a value of 0.65 mm. For the segment C2-T1, data on intradiscal pressure, stress plots and displacements during flexion were obtained. The maximum stress value of 10.036 MPa is observed in the C3-C4 disc.

CONCLUSION

Simulation results using the proposed methodology are in good agreement with experimental data. The generated biomechanical models allow describing dynamic phenomena in the cervical spine and obtaining a wide range of quantitative properties of anatomical objects, which are otherwise inaccessible to classical methods for studying dynamic and functional anatomy.

CLINICAL-MORPHOLOGICAL CLASSIFICATION OF ACUTE THROMBOSIS OF THE EXTERNAL HEMORRHOID NODE IN RELATION TO A DIFFERENTIATED APPROACH IN ITS TREATMENT

Acute thrombosis of the external hemorrhoid node is one of the common manifestations of hemorrhoids and a frequent reason for seeking specialized medical care. Despite existing prospective studies proving the effectiveness of operative treatment, there is no clear position in determining the indications, timing and methods of surgery, nor the combination of the latter with conservative therapy.The article formulated and described the original clinical-morphological classification of acute thrombosis of the external hemorrhoid node based on the data of its ultrasound examination (ultrasound). Effectiveness of various methods of treating acute thrombobosis of external hemorrhoid node, carried out on the basis of proposed classification, is evaluated.Purpose of the study. Improving treatment outcomes for patients with acute thrombosis of the external hemorrhoid node.Results. Ultrasound types of thrombosis of external hemorrhoidal node are revealed:

– mononuclear (in ultrasound, it is a single thrombus or a dense, intimately soldered group of thrombotic masses of an an- or isoechogenic structure with untested swelling of the skin and subcutaneous fat (PWD), from 10 mm or more in size);

– polynuclear (clusters of thrombotic masses of an- or isoechogenic structure up to 10 mm in size, located at a short distance from each other, with moderate swelling of the skin and subcutaneous fat);

– edema (during sonography, multiple small, up to 2–3 mm, anechogenic thrombotic masses are visualized against the background of pronounced edema of subcutaneous fat fiber and skin).

Effectiveness of various methods of treating patients with acute thrombosis of external hemorrhoid node in groups formed on the basis of proposed classification is evaluated. It has been found that in patients with edematous sonographic type of thrombosis, it is more advisable to apply only conservative therapy or carry out surgical treatment after completion of taking diosmin-containing preparations. Such tactics reduced the duration of treatment and reduced pain syndrome. In patients with a mononuclear type of thrombosis of the external hemorrhoidal node, a similar result was noted during surgery and the beginning of conservative therapy on the day of circulation.Conclusion. Application of ultrasound diagnostics allows establishing the type of hemorrhoid node thrombosis and using the obtained data when choosing treatment tactics. A differentiated approach to treating this category of patients, based on the proposed classification, allows improving the treatment results of patients with acute thrombosis of the external hemorrhoid node.

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[Surgical strategy for wounds of the cervical part of the esophagus]

An analysis of results of treatment of 425 patients aged from 15 to 85 years with penetrating wounds of the neck was made. In 40 (8.1%) patients there were wounds of the cervical part of the esophagus, 29 of them had associated injuries. The proposed active surgical strategy consisted in a necessary thorough revision of the penetrating wounds of the neck using general anesthesia and then directly in the operation room using subsidiary methods of examination such as urgent x-ray analysis with a water-soluble contrast, esophagoscopy, larengotracheoscopy. This approach allowed detection of injuries of the cervical part of the esophagus, even in cases of the absence of clinical symptoms of esophagus injuries. In all the patients the wounds of the esophagus were sutured and followed by active aspiration drainage and antibacterial treatment with modern antimicrobial medicines.

[The diagnosis and treatment of injuries of the upper respiratory tract in wounds and traumas of the neck]

The authors made an analysis of results of treatment of 339 patients with wounds and closed injuries of the neck. Laryngotracheal injuries were found in 27 (7.9%) patients, in 15 patients the injuries being of combined character. Active surgical strategy including the necessary thorough revision of the penetrating wounds of the neck during operation under general narcosis anesthesia, by instrumental methods of examination. Such strategy allowed timely detection and adequate elimination of injuries of the organs and vessels of the neck and improvement of the results of treatment of such patients.

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The article presents an experience with the work of a city phlebologic center, confirming the importance of active introduction of modern surgical methods of prevention of embolism of the pulmonary artery in the program of aid to patients with acute embologenic iliofemoral phlebothromboses. Use of the methods of endo- and exovenous cava filtration and cavaplication allowed lethality in this group of patients to be reduced from 15-20% to 1%.