颈椎曲度（cervical lordosis）Is one of the 4 physiological curvature of the spine, its existence not only directly guarantee the normal physiological function of the spine, but also on the human body to maintain the center of gravity and buffer shock plays a very important role. In recent years scholars on cervical curvature change more and more attention, cervical curvature anomalies can be as the objective criterion for diagnosis of chest X - ray and early diagnosis of cervical disease in the majority of patients has important significance.
This paper analyzes all kinds of measuring methods of cervical curvature and its clinical significance is summarized as follows.
The normal physiological characteristics of 1 cervical curvature.
The sagittal cervical spine has a normal physiological lordosis curvature. Studies have shown that the formation and maintenance of [2], the physiological curvature of the cervical spine rely mainly on intervertebral disc before and after height difference and anterior vertebral column space sequence between mutual connection, the body's physiological function, motor function plays a very important role. Support structure of the cervical curvature is the body function, is also affecting the physiological function of the structure.
Maintain the normal cervical lordosis balance dependent on a variety of factors, including the elastic neck circumference muscle coordination, ligaments and intervertebral disc, vertebral shape by static balance and dynamic balance system two parts to maintain. A closed supporting system is made up of the cervical intervertebral joint composed of intervertebral disc, bilateral hook joint and joint facet joint.
Measurement methods and evaluation of 2 cervical curvature.
In recent years, with the high incidence of cervical spondylosis and younger, cervical curvature and increasingly become the focus of specialist attention, cervical curvature measurement method is more, but the existing research show [3], using different measurement method can directly influence on cervical curvature abnormality judgment, so the choice for the cervical curvature measurement method is particularly important. Cervical physiological curvature changes with the change of head and neck posture, to determine the physiological curvature of the cervical spine is normal or not should be the strict standards of neutral lateral radiographs, otherwise it may cause abnormal curvature of cervical vertebra physiology of false positive findings. Under normal circumstances, patients take the right standing position, bipedal apart, hands and shoulders drooping naturally, focal film distance is 120 mm, with eyes look straight ahead, the hard palate and the X - ray film parallel to the edge of the, mandibular angle projection on the X-ray films, the center line alignment C4, taken spinous process of the scope to the occipital protuberance to T2. Grob [4] study found that in the angle of shooting cervical lateral position X-ray films horizontal line and inspected the ipsilateral tragus and corner of the connection is easy to control and the lateral cervical radiographs taken and define the subjects in natural vertical position to maintain the angle of 20 degrees, this method can maximum limit eliminates the influence of body position on cervical physiological curvature measurement accuracy. Research [5] found that photo films body of different postures, such as pelvic tilt and, sitting or standing position, the seat when the shape of the backrest and the position of the head can be measured directly affect the curvature of cervical vertebrae. Therefore, establishment of a standard projection position is group of cervical curvature on the premise of assurance, and relative homogenization of individual investment is to ensure consistency of baseline differences before and after the study of individual cervical curvature according to standard.
The clinical use of the cervical curvature measurement method have five, including Borden method, Harrison, Cobb's method, Ishihara and CCL angle measurement method, and can be divided into two types of angle measuring method and depth measurement method.
2.1 Borden method. The clinical use of Borden is the most widely used. Most early in 1960 by Borden [6] reports, on behalf of the depth measuring method, in particular since after odontoid edge to C7 posterior margin of painting a straight line is a line, along the cervical vertebral draw a line for line B in a - B line between the widest at the vertical cross intersection line C, namely for the depth of the physiological curve of cervical vertebra, measurements were to the absolute value of the said. The advantage of this method is that it can avoid the effect of vertebral degeneration, but the individual bone size difference and the X line amplification rate are the interference factors affecting the accuracy of the measurement data.
2.2 Harrison method. As an angle measurement method, its advantages are simple and convenient. The specific methods are: the C2 and C7 posterior margin of the vertebral body is tangent, and the angle between the two lines is taken as the angle of the cervical vertebra (CSA). This method can be used not only for the angle measurement of the whole neck, but also more accurate for each segment of the cervical spine. But easy to be influenced by osteophyma and lead to misjudgment.
2.3 Cobb method. Currently used in clinical measurement and scoliosis kyphosis in the preoperative preparation. Specific measurement methods: the lower margin of the vertebral body and the C7 of the C2 vertebral body to make tangent, tangent line between the angle between the cervical curvature. Generally speaking, is widely used in the two methods C1-C7 Cobb angle and Cobb angle of the C2C7 (9). C1 C7Cobb angle measurement and C2 to C7Cobb angle of measurement compared, because C1 - C2 vertebral hyperextension and measure the Cobb method will overestimate C1 - C7 lordosis; and C2 vertebral body under the edge of the hook nose shape structure, Cobb measurement rule will underestimate C2 to C7 lordosis.
2.4 Ishihara's method. Also called curvature method. Specific measurement method for a corner connection of C2 vertebra after corner and C7 vertebra, by the vertebral C3C6 after angle connection of a vertical, respectively obtained connection A1, A2, A3 and A4, measured the length of above indexes, and then through the formula: 100 x (A1a2a3a4) / A, the cervical vertebra curvature [10-11]. The index had no direction, the essence of which is on behalf of cervical vertebral body posterior edge connection arc and odontoid process trailing edge to C7 trailing edge connection between regions, but clinically because of their individual differences larger, cervical curvature change straight or S-shaped variation index is higher and the calculation is relatively complex.. therefore, the application of less.
2.5 CCL vertebral (centroid measurement of cervical lordo-sis) measurement method. Cervical vertebral angle measurement method, the earliest in 1998 by Harrison [8] use to measure the lumbar lordosis, later came to be applied to measure the curvature of cervical vertebrae. Specific measurement method: take the point of intersection of the C3, C6, C7 vertebra diagonal a, B, C, reassume C2 vertebral margin of the tangent point is called a point, formed by the AA line and BC line angle is the angle of CCL [3]. Measurement of CCL angle can also analyze the curvature of the adjacent vertebral bodies, but the disadvantage of mapping measurement procedures more complex, practical sex is a bit poor, clinical use less.
As the methodology research, repeatability and stability is must have, the five kinds of cervical curvature measurement method in measuring the same and different measurement repeatability were higher that have good repeatability. But different methods of study on the correlation between the controversial, Wan [7] to study found that Borden method measuring cervical curvature consistency is Harrison's method. Ishihara, Cobb's method, Harrison and CCL angle measurement method in normal cervical curvature has a good correlation, and cervical curvature occur abnormal change poor correlation, which C1 - C7 Cobb angle method including Cobb angle of C1 - C2, while the latter and the normal vector of the cervical vertebra to sequence was negatively correlated, so the relevance of C1 - C7 Cobb angle method and other methods were lower (3). Harrison et al. Two kinds of Cobb angle method and Harrison method were compared and analyzed. The results showed that the 3 had high reliability and validity (group ICC > 0.7), while the Harrison method had smaller standard error, so it was better than the Cobb angle measurement. Zhao Yu et al. In the study of patients with cervical spondylosis, cervical curvature index of Ishihara method and Harrison method were significantly correlated.
The author thinks that the study on the correlation between cervical curvature now seems to lack a large sample of research, and different measurement methods in different types of clinical studies should focus.
3 the clinical significance of cervical curvature measurement.
The significance of cervical curvature measurement should eventually return to clinical and different cervical curvature directly determines the cervical vertebrae bear the weight of the skull of different stress distribution, corresponding force action point and vertebral biomechanical properties change, and cervical maximum load. According to the mechanical structure of the human body with the load, the head and neck of the load is concentrated in the lower neck, under normal physiological conditions, the pressure stress of C4 is the largest. In Wei et al [13] cervical curvature change the straight model, cervical activity than normal range was reduced by 24% ~ 33%, the stress increased by 5% to 95%, C3, C4, 5 joint facet, hook vertebral joints, intervertebral disc stress concentration. Grob [4] through experiments showed that abnormal curvature of cervical vertebrae cervical maximum stress position in the C4, 5, followed by C5, 6 and C3, 4. Lee [14] is system of degenerative cervical retrospective study, cervical vertical force line intersect to C4. 5 clearance, indicated here by stress and distortion of the largest, and flexion, the maximum pressure and distortion in C5, 6 intervertebral space. So to maintain long-term cervical flexion posture is not only easy to change the cervical lordosis, more likely to induce the occurrence of cervical spondylosis.
It is also indicated that the diameter of the intervertebral foramen of the cervical spine was increased by 10% and 13%, respectively, when the cervical flexion was 20 and 30, respectively, and the diameter decreased by 8% and 10%, respectively. Visible cervical physiological curvature determines the size and range of intervertebral foramen, and also determines the sequence of spinal canal diameter and cervical vertebra transverse process between the holes, which leads to symptoms such as headache, dizziness, walking lead to instability of the compression of the spinal cord, nerve root and vertebral artery morphological changes induced. At the same time in a large-scale epidemiological survey also found that in the neck pain in the neck, neck pain, cervical curvature, 36.5%, neck "S" - shaped change accounted for 10%, 17% of the cervical curvature after 16. These data fully demonstrated that the muscle spasm caused by abnormal cervical curvature is one of the important causes of neck pain. Scholars [17] proposed neck muscles there are a lot of proprioceptors, cervical curvature change will inevitably lead to neck muscle tension change and cause neck extensor group of proprioceptive information change, resulting in cervical vertigo [18].
McAviney et al. Found that CSA was less than 20 and 31 ~ 40. The relationship between the Grob [4] to study in elderly patients with cervical curvature change and cervical pain, found in elderly patients with neck pain and cervical curvature abnormality between the two is consistent.
Cervical curvature anomaly appeared early, change significantly, easy observation is various types of cervical spondylosis early most common X-ray film, but also throughout the pathogenesis of cervical spondylosis. Measurement of normal cervical lordosis average value will become one of the important indexes for evaluation. Clinical can be broadly cervical curvature abnormality of cervical curvature straight, the posterior convex, cervical sagittal "s" shape change and cervical lordosis with the top of the arc (normal to C4) shift, cervical lordosis with arc top downward. The general increase of cervical lordosis seen in normal adolescents and compensatory severe thoracic kyphosis change. With the increase of age, cervical curvature gradually decreased until kyphosis. From the age level analysis, normal human at 25 cervical gradually began to degenerate, osseous tissue and intervertebral disc degeneration caused by intervertebral tension decreased, loose instability, on the one hand, by the long-term bad posture, cold and other external effect directly caused by cervical biomechanical imbalance and defensive now muscle spasm; on the other hand vertebral lost steady stimulus around the sinus vertebral nerve neck ache bilges and other clinical symptoms. This disappearance of cervical curvature and symptoms and signs of a significant positive correlation, treatment should be to restore the cervical curvature is the important goal. For the elderly, the change of cervical curvature and the more important reason is caused by degeneration of the intervertebral disc Pro hydraulic drop, intervertebral height loss; facet joint bone hyperplasia, facet joint surface direction change. At the same time, can cervical curvature change depending on the physiological changes. Some scholars (20) proposed the excessive emphasis on the steady recovery of cervical curvature may damage the cervical vertebra. In addition to the above physiological reasons caused by the curvature change, there is a class is caused by acute traumatic cervical muscle spasm, that facet joint in subluxation state, at this time should be attention to reconstruction of the cervical curvature.
Cervical curvature is a reflection of the cervical balance of important indications of doesn't exist in the clinical symptoms, the restoration of the physiological curvature of the cervical spine to prevent further degeneration of adjacent segment and the whole of the cervical spine has a positive role; to have suffered from [21] of the cervical intervertebral disc herniation, Chi-ba found through reconstruction of cervical curvature can indirect decompression of the spinal canal is to restore the effective volume of the spinal canal is a kind of important means.
Combining can roughly determine the severity of cervical spondylosis patients symptoms, signs and accurate cervical curvature measurement, also for the correct choice of treatment plan provides the beneficial reference. Conservative treatment of patients, can be very intuitive, easy to understand the progress of treatment by measuring cervical curvature. Surgical treatment of patients, preoperative can be formulated by measuring the curvature of cervical vertebrae operation, through the improvement of cervical curvature of the diseased segment thorough decompression, full integration and restore the normal cervical stress distribution, so as to prevent the generation of adjacent vertebral disease, after operation can be based on the evaluation of the efficacy. Thus, in the clinical work in cervical curvature measurement should not only as a diagnostic method, should be used as basis for choice of treatment methods and evaluation of therapeutic effect.
4 conclusion.
In summary, cervical curvature change has become a standard of early diagnosis of cervical spondylotic myelopathy, and as the evaluation of curative effect of treatment on, but in the cervical spine X-ray acquisition position need standardization, reduce the error of the baseline. Although the existing methods of measurement have their own literature support, but the relevance of the larger, the lack of evidence of large sample support. In the static and dynamic cervical curvature change, the lack of research methods of measurement. With the further development of imaging, cervical 3D CT reconstruction technique widely used seems to further study of cervical curvature provides more realistic 3D image data.
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