Congenital kyphosis

The peculiarity of congenital kyphosis makes it necessary to consider this type of spinal deformity separately. Traditionally, the group of congenital kyphosis includes not only single-plane sagittal deformities or so-called "pure" (English "rige") kyphosis, but also kyphoscoliotic deformities with a leading kyphotic component. At the same time, almost all authors point to significant differences in the course of pure kyphosis and combined kyphoscoliosis and consider the presence of a scoliotic component to be an element of defect compensation, "saving" the body from the development of a vertebral-spinal conflict and the development of myelopathy. The number of observations of "pure" congenital kyphosis only in rare, almost isolated works exceeds 30 cases.

At present, the classification of congenital kyphosis by R. B. Winter (1973) is considered "basic", and no publication on the problem under consideration can do without references to it. Earlier classification schemes are not currently used independently. R. B. Winter identified three types of congenital kyphosis: type I kyphosis with anomalies in the formation of vertebral bodies, type II kyphosis with anomalies in the segmentation of vertebral bodies, and type III kyphosis with mixed anomalies.

In the same year 1973, Ya. L. Tsivyan also identified three types of congenital kyphosis: kyphosis with a wedge-shaped (complete or supernumerary) vertebra, kyphosis with aplasia of the body (bodies) of the vertebra (vertebrae), and kyphosis with concrescence of the vertebral bodies.

The most detailed scheme of congenital kyphosis, based on the experience of the Novosibirsk Center for Spinal Pathology, is given by M.V. Mikhailovsky (1995). However, the author analyzes not so much "pure" congenital kyphosis, as congenital deformations of the spine, accompanied by a kyphotic component. That is why the classified group includes kyphoscoliosis, which accounts for up to 75% of all deformations considered by the author.

Classification of congenital spinal deformities accompanied by a kyphotic component.

Classification feature	Evaluation parameters
I. The type of anomaly on the basis of which the deformation developed	Posterior (posterolateral) vertebrae (hemivertebrae); Absence of the vertebral body (asomia); Microspon dilia; Concretion of the vertebral bodies - partial or complete; Multiple anomalies; Mixed anomalies.
II. Type of deformation	Kyphosis; Kyphoscoliosis.
III. Localization of the deformation peak	Cervicothoracic; Upper thoracic; Mid-chest; Lower thoracic; Thoracolumbar; Lumbar.
IV. The magnitude of kyphotic deformity (degree of deformity)	I degree - up to 20°; II st. - up to 55°; III st. - up to 90"; IVst. - over 90°
V. Type of progressing deformation	Slowly progressing (up to 7° per year); Rapidly progressing (over 7° per year).
VI. Age of initial detection of deformation	Infantile kyphosis; Kyphosis in young children; Kyphosis in adolescents and young men; Kyphosis in adults.
VII. Presence of involvement of the contents of the spinal canal in the process	Kyphosis with neurological deficit; Kyphosis without neurological deficit
VIII. Associated anomalies of the spinal canal	Diastematomyelia; Diplomyelia; Dermoid cysts; Neuroenteric cysts; Dermal sinuses; Fibrous constrictions; Abnormal spinal roots
IX. Associated anomalies of extravertebral localization	Cardiopulmonary system abnormalities; Anomalies of the chest and abdominal wall; Anomalies of the urinary system; Limb anomalies
X. Secondary degenerative changes in the spine	None They appear in the form of: Osteochondrosis; Spondylosis; Spondyloarthrosis.

In our study we managed to combine the experience of several world clinics - Twin Cities Spine Center, MN, USA, State Pediatric Medical Academy and Research Institute of Phthisiopulmonology, St. Petersburg, Russia, while the total number of patients with pure congenital kyphosis exceeded 80 people. This allowed us to detail the anatomical and radiological classification of RBWinter. In the course of the study, not only radiological data were taken into account, but also the results of modern methods of radiation diagnostics, primarily magnetic resonance imaging. We realize that even in this form the presented classification cannot be considered complete. RB Winter described the effect of "spontaneous fusion" of vertebral bodies in the natural course of deformation, consisting in the concrescence of vertebral bodies, which were initially visualized on radiographs as segmented. Our experience has shown that during MRI examination of patients with spontaneous fusion, hypoplasia of intervertebral discs was detected already at the initial visit in the form of absence of glow of pulpous nuclei. During the growth process at the level of hypoplastic discs, secondary degeneration with segmental instability of the spine developed in some patients, while in others - true bone blocking.

Modified classification of pure congenital kyphosis

Type of kyphosis

Variants of deformations

Type I - congenital kyphosis caused by abnormal formation of the vertebral bodies. Type II - congenital kyphosis caused by a violation of the segmentation of the vertebral bodies Type III - congenital kyphosis caused by mixed or undifferentiated developmental defects

A- agenesis of the body, B - hypogenesis of the body, the preserved part of the body is less than 1/2 of its normal size, C - body hypoplasia, the preserved body part is more than 1/2 of its normal size. A - true fusion of the vertebral bodies, confirmed by X-ray and MRI data; B - disc hypogenesis: presence of radiographic signs of fusion of the vertebral bodies while maintaining the disc image according to MRI data; the nucleus pulposus is hypoplastic; C - disc hypoplasia: the disc is radiographically preserved, but reduced in height; on MRI, the disc is devoid of the nucleus pulposus.

The table provides data regarding the characteristics of the spinal canal in various types of congenital kyphosis and the frequency of secondary neurological complications (myelopathies) in them.

Sagittal spinal stenosis and incidence of neurological disorders in pure congenital kyphosis

Type of kyphosis	Average spinal canal narrowing (%)	Frequency of neurological disorders (%)
1 type:
I.A.	53	64
IB	36	30
1C	13	17
Type II	10	-
Type III	25	36

If the relationship between the severity of the defect and the frequency of myelopathies in type I kyphosis seemed predictable to us, then the absence of neurological disorders in type II kyphosis turned out to be unexpected, especially since this group also included patients with grade IV deformations. This refutes the opinion about the leading significance of the magnitude of kyphotic deformation in the occurrence of neurological complications of congenital kyphosis.

Research data indicate that spinal canal stenosis plays a major role in their development.

It should also be noted that in almost 20% of patients with congenital kyphosis, we identified various variants of myelodysplasia, and in almost half of the cases its course was asymptomatic.

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