X-ray anatomy of the spine is normal

The structure of the spine is characterized by significant differences in different age periods. The very concept of the norm is not static and implies the presence of age-related features of the structure and shape of individual vertebrae and the spine as a whole, the ratio of the sizes of the vertebral bodies and discs, certain values of the bone canals formed by the vertebrae, the boundaries of the functional mobility of the vertebral-motor segments, etc.

The shape and structure of the vertebrae in the age aspect in the radiological image

Age	Form	Central slits of feeding vessels	Lines of force of the vertebrae
0-6 months	Biconvex	Expressed	Absent (or weakly expressed) arcuate and radial lines.
6 months - 2 years	Biconvex	Expressed	Single at the end of the period.
2-4 g.	Beginning of flattening	They are often more pronounced in the thoracic region and vary in the depth of penetration into the vertebral bodies.	Longitudinal lines of force are expressed, and arcades of force appear in the arcs.
4-6 years	Gradual transition to a rectangular shape	Shallow, pit-shaped cracks. May be deep, sclerotic. The persistence of pronounced gaps indicates dysplasia.	Development of vertical and horizontal lines. The final construction of power arcades in arcs.
Over 6-7 years old	Rectangular shape, the appearance of concavity of the centers of the epiphyseal plates, anterior and posterior sections. The appearance of "steps" corresponding to the position of future apophyses	Same	Further strengthening of power lines.

During the growth process in children, a uniform increase in the size of the vertebral bodies and discs in the caudal direction is observed, starting from T3. The increase fluctuates from 1 to 2 mm, but is strictly individual. Violation of the uniform increase in the size of the vertebrae and discs is usually observed in pathological conditions - vertebral dysplasia, trauma, tumors, inflammation, etc.

Another indicator characterizing the correct development of the spine is the spinal-disc ratio - the ratio of the height of the vertebral body to the height of the contact disk. Its value normally fluctuates between 5:1 and 4:1, and a decrease in the indicator is observed in systemic diseases that occur with damage to the spine - imperfect osteogenesis, dyshormonal spondylopathy, leukemia, etc.

The concept of age norm includes physiological periods of vertebral maturation - the appearance of radiographically visible ossification nuclei and closure of interstitial growth zones. It is not by chance that we speak about the periods of radiological closure of growth zones, since the analysis of magnetic resonance tomograms of the spine allows us to assert that radiographically visible bone fusion is not always confirmed by MRI data. This is especially clearly manifested in the assessment of the corporodental synostosis of C2 and the sacral and coccygeal vertebrae - even in adult patients, synchondrosis zones are preserved on MRI.

In 8-10% of people, the L5 and S1 arches do not fuse. If the absence of arch fusion is not accompanied by their dysplasia (hypoplasia, deformation, different angles of departure, etc.), then this is considered a normal variant. In the presence of arch dysplasia, we should talk about Spina bifida dysplastica.

Normal dimensions of the spinal canal. Deviation of the spinal canal dimensions from normal values is of fundamental importance. Widespread narrowing of the spinal canal dimensions is characteristic of some systemic skeletal diseases (for example, achondroplasia), local narrowing is characteristic of congenital and acquired stenosis. Enlargement of the spinal canal is observed in dysplastic processes, malformations of the spinal canal and spinal cord, long-standing volumetric processes in the spinal canal (see Elsberg-Dyke syndrome), and some types of spinal injuries.

Functional mobility of vertebral-motor segments. Isolation of the functional motor unit of the spinal column - the vertebral-motor segment (VMS), allows us to estimate the range of motion at the level of each segment. Movements in the VMS are carried out by the facet joints and intervertebral discs. It is obvious that movements in the VMS vary along the spine not only in volume, but also occur in different planes. This is explained by the peculiarities of the anatomical structure and spatial orientation of the intervertebral joints - the so-called tropism.

Skeletal maturity indices

Clinical and radiographic indicators used to assess skeletal maturity also reflect the degree of completion of spinal growth. Most often, the degree of ossification of the apophyses of the vertebral bodies is used to directly assess the maturity of the spine. Indirectly, the maturity of the skeleton (including the spine) is determined by the Risser apophyseal test and the Tanner sexual maturity test. It should be noted that the last two tests have found the greatest application in practical vertebrology and are used to determine the probable progression of spinal deformities in adolescents.

The degree of ossification of the apophyses of the vertebral bodies

The ossification nuclei of the apophyses of the vertebral bodies in different parts of the spine do not appear simultaneously. They are detected earliest in the vertebrae of the cervical and upper thoracic sections and then "spread" in the caudal direction. At the same time, in different parts of the spine, age differences in the degree of maturation of the vertebrae can reach 4 years. To determine the bone age, they focus on the latest stage of ossification present in a given child.

P. Stagnara (1974, 1982) identifies the following stages of the ossification process of the vertebral body apophyses: 0 - absence of ossification nuclei of the end plates of the vertebral bodies, 1 - appearance of punctate ossification nuclei of the apophyses, 2 - clearly visible triangular shadows of the apophyses without fusion with the vertebral bodies, 3 - initial signs of fusion of the apophyses with the vertebral bodies, 4 - almost complete fusion of the apophyses while maintaining their traceable contour, 5 - complete fusion of the apophyses.

A detailed description of the processes of ossification of the apophyses of the vertebral bodies is also given by V.I. Sadofyeva (1990):

Stage I - the appearance of single point ossification nuclei, stage II - multiple insular ossification nuclei, stage III - ossification nuclei merge in the form of "stripes", stage IV - initial signs of fusion of apophyses (usually in the central sections), stage V - complete fusion, however, areas of enlightenment are visible, stage VI - complete fusion (completion of vertebral maturation).

Risser's apophyseal test (Risser J-C, 1958). The indicator, which received the name "Risser's test" and has a standard letter designation R, is determined by the prevalence of the ossification zone of the apophysis and its fusion with the wing of the ilium.

The test is used as one of the main signs for determining the potential for progression of idiopathic spinal deformities in children and adolescents.

To determine the grade of the Risser test, the iliac wing crest is conventionally divided into 4 equal parts. The first foci of ossification of the iliac crest appear in its anterior sections and extend from the anterior-superior to the posterosuperior spine. The absence of apophyseal ossification zones is assessed as R0 and corresponds to a high potency of skeletal growth. R1-R4 indices correspond to different phases of apophysis ossification, and R5 to complete fusion of the ossified apophysis with the iliac wing and cessation of skeletal growth. The ossification center of the iliac crest at the level of the anterior-superior spine, corresponding to R1, appears at the age of 10-11 years. Complete ossification of the apophyses to stage R4 takes a period from 7 months to 3.5 years, averaging 2 years. The closure of the apophyseal growth zone (R5 indicator) is observed on average between 13.3 and 14.3 years in girls and between 14.3 and 15.4 years in boys, but can also be observed at a later date, especially in children with delayed skeletal maturation (so-called bone infantilism).

It should be remembered that the local bone age of the iliac bones does not always coincide with the bone age of the spine. Therefore, the Risser test is not absolutely accurate, but it is the easiest to determine and has a high degree of reliability in assessing the progression of scoliosis.

The Tanner test reflects the degree of sexual maturation of adolescents and includes the determination of the severity of secondary sexual characteristics (T-system) and the role of pubic hair (P-system). The severity of manifestations of the signs of the T- and P-systems has a certain parallelism, but absolute coincidence of stages is not observed.

Completion of puberty, corresponding to T5 and P5 stages, is associated with the completion of hormonal changes and is accompanied by a slowdown and then cessation of skeletal growth. This is why the Tanner test is used to predict the possible progression of idiopathic (dysplastic) spinal deformities.

Another sign of puberty in adolescent girls is the time of the first menstruation. In the individual development chart (medical history) of the patient, this indicator is recorded with the letter designation M (menarche) and a digital designation of the terms from menarche (year + month). It has been established that in more than 75% of girls, menarche coincides with the Risser test indicator corresponding to R1, and in more than 10% - with R2. The time of the first menstruation is also used to predict the course of idiopathic spinal deformities - their progression after the onset of menstruation, as a rule, slows down, but can still be observed over the next 1.5-2 years.

The various stages of adolescent sexual development coincide with the period of the second growth spurt. In girls, the onset of the growth spurt precedes the onset of puberty, and the peak of the spurt coincides with stage T3. The slowdown of the growth spurt coincides with the onset of menarche. In boys, the growth spurt begins after the first signs of puberty, and the peak of the spurt coincides with stage T4.

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