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.

[The use of the osteopathic correction for the combined treatment and rehabilitation of the patients presenting with the vertebral artery syndrome]

BACKGROUND

The pathological changes in the cervical spine frequently result in the disturbances of the blood supply in the vertebral-basiliar system. The degenerative-dystrophic processes in the cervical spine occupy the leading place in the pathogenesis of the vertebral artery syndrome (VAS) causing disorders of the microcirculation and innervation, as well as the restriction of mobility and the development of somatic dysfunctions. It can be assumed that the manual methods applied to manage this condition can be effective in the removal the functional abnormalities in the blood flow.

AIMS

The objective of the present study was to evaluate the effectiveness of the osteopathic treatment as a component of combined therapy of the patients presenting with the vertebral artery syndrome.

MATERIAL AND METHODS

This experimental prospective controlled randomized study was conducted during the period from January 2015 till January 2017. A total of 106 patients with VAS, aged from 20 to 60 (the average age was 43.1±1.0 years) took part in the study. The patients were divided into three groups. The experimental group was comprised of 40 patients who received the medicamentous and osteopathic treatment. The control group consisted of 40 patients given the medicamentous treatment alone. The group of comparison contained 26 patients treated with the use of pharmacotherapy and massage. The methods finding application in clinical neurology, clinical osteopathy, and ultrasonic diagnostics of the brachiocephalic vessels were employed to evaluate the health status of the patients and evaluate the effectiveness of their treatment.

RESULTS

The combined treatment of the patients comprising the experimental group with the use of osteopathic correction and pharmacotherapy produced the positive effect and resulted in the normalization of the neurological status of the patients; specifically, the incidence of both subjective and objective (neurological) symptoms was reduced. Simultaneously, the incidence of somatic dysfunctions at all levels of their manifestation decreased as compared with their frequency in the patients of the control and comparison groups. The results of the ultrasound examination of the great vessels of the neck and the brain in the experimental group made possible the evaluation of the dynamics in the incidence of the major pathological changes in the vessels of the vertebral-basiliar basin (VBB). It was shown that the occurrence of such serious changes as venous dishemia, reduction of the vasoconstriction and vasodilation reserves in VBB, in the patients of the experimental group vessels fell down by 32.1% (p<0.001), in comparison with only 12% (p<0.05), in the control group and 6,27% in the group of comparison (p>0.05).

CONCLUSION

The osteopathic manipulative treatment included in the combined therapy of patients with VAS based on the personified approach to the management of individual cases, detection and correction of each clinically significant functional disorder accompanying the pathological process greatly contributes to the regression of the neurological symptoms, elimination of somatic dysfunctions at different levels of the body, normalization of the blood flow in the vessels of the vertebral-basilar system. Taken together, these effects prolong the beneficial results of the combined rehabilitative treatment of the patients with the vertebral artery syndrome based on the application of standard pharmacotherapy and correction of the functional disorders with the use of the osteopathic methods.