Spondylolysis, spondylolisthesis and back pain

Spondylolysis (verbatim: "resorption of the vertebra") - the term adopted to denote the defect of the interarticular part of the arch of the vertebra. The term spondylolysis reflects an x-ray symptom rather than the anatomical nature of the pathology, since in most cases the presence of this bone defect is due to the not acquired "resorption" of a certain vertebral zone, and its vicious development is dysplasia. The frequency of spondylolysis in the population exceeds 5%. Spondylolysis is usually bilateral, in 85% of cases localized at the level of L5, about 10% - at the level of the L4 vertebra. When unilateral damage is more often revealed on the right. In almost 70% of cases, spondylolysis occurs asymptomatically and is accidentally detected by X-ray examination. In the presence of clinical manifestations, the main symptom of the pathology is back pain, namely in the lower lumbar or lumbosacral spine, usually associated with abnormal mobility of the vertebral arch.

In childhood and adolescence, spondylolysis often combines with spondylolisthesis, which is an independent disease. The term spondylolisthesis was introduced by HF Kilian (1854) to denote the displacement of the body of the overlying vertebra relative to the underlying in the horizontal plane. In the direction of displacement, anterolisthesis (anterior displacement), retroolisthesis (posterior displacement) and laterolisthesis (lateral displacement) are isolated. Most often, spondylolisthesis is detected at the level of lower lumbar (L4-L5) and lumbosacral (L5-S1) vertebral-motor segments, which account for more than 95% of cases. There are clear sexual and racial differences in the frequency of spondylolisthesis: the incidence of pathology is 5-6% in Caucasoid men and 2-3% in women. At the same time, among the Eskimos, pathology occurs in 50% of the population (!), While in African Americans - less than 3%.

Classification of spondylolysis

By pathogenesis:	A) congenital spondylolysis - developmental malformation (dysplasia) of the vertebral arch; B) acquired spondylolysis, including: - with functional overloads of dysplastic vertebrae (for example, with sacralization or violations of tropism of the lower lumbar vertebrae); - "overload" spondylolysis (by the type of "Lozera zone"), with functional overloads of the initially normal spine.
Fragment localization	A) typical - in the interarticular part of the arch; B) atypical, including: - Retrosomatic - at the level of the arch leg; - Retrospermuscular - posterior to articular processes
According to the clinical course	A) asymptomatic, B) with pain syndrome, including: - without spondylolisthesis, - with spondylolisthesis.

The classifications of spondylolisthesis are generally recognized, based either on the determination of pathogenetic mechanisms of pathology, or on the quantitative evaluation of the degree of "slippage".

Pathogenetic classifications of spondylolisthesis

Authors	Types of spondylolisthesis
WiltzeLJL, Newman RN, Macnab I. (1976)	Dysplastic spondylolisthesis. Ishrmic or cervical (spondylolytic). Degenerative (senile) spondylolisthesis. Traumatic spondylolisthesis. Pathological (tumor, osteomyelitic) spondylolisthesis.
Wiltze LL, Rothmans, 1997	Congenital spondylolisthesis: A - with L5-S1 dysplasia, joints and their horizontal orientation; B - with sagittal orientation of intervertebral joints; C - with congenital anomalies of the vertebrae of the lumbosacral zone. Isthmic (cervical) spondylolisthesis: A - with spondylolysis; B - with lengthening of the interarticular zone, with or without spondylolysis; With - at a trauma of an interarticular zone. Degenerative, incl. Senile spondylolisthesis associated with natural or pathological joint degeneration. Traumatic spondylolisthesis with damage to the vertebrae outside the interarticular zone. Pathological spondylolisthesis incl. With osteomyelitis or with local cancer lesions. Post-surgical spondylolisthesis (after decompression of the spinal cord, nerve root or after laminectomy).

From the methods of quantitative evaluation of spondylolisthesis, the simplest method is HW Meyerding'a (1932): the cranial closure plate of the underlying vertebra is conventionally divided into 4 equal parts, and the perpendicular from the posterior end of the superior vertebra to the closure of the lower vertebrae is lowered. The degree of leafage is determined by the area to which the perpendicular is projected. More precisely, the magnitude of spondylolisthesis is characterized by determining the percentage of slippage of the vertebra calculated by the Meyerding method using formula

A / bx100%,

Where a is the distance from the posterior edge of the lower vertebra to the perpendicular drawn through the posterior edge of the superior vertebra, b is the anteroposterior size of the upper closure plate of the lower vertebra. Thus, the first degree of slippage corresponds to a shift of up to 25%, the second - from 25 to 50%, the third - from 50 to 75%, the fourth - from 75 to 100%. The fifth degree of spondylolisthesis (or spondyloptosis) is characterized not only by the horizontal mixing of the superior vertebra anterior to the full anteroposterior body size, but also by its additional caudal displacement.

There are other quantitative indicators that characterize the relationship of the vertebrae of the lumbosacral zone, such as the slip angle, the angle of sagittal rotation, and the incidence angle (incline) of the sacrum. These angles are calculated from the lateral radiograph of the spine.

The slip angle reflects the magnitude of the lumbosacral kyphosis. It is formed by the intersection of the line tangential to the lower closure plate of the superior vertebra (L5) with the perpendicular restored through the upper closure plate of the lower vertebra (S1) to the line tangential to the posterior surface of its body. Normally, the slip angle is 0 or has a negative value.

The angle of sagittal rotation is determined by the intersection of the lines drawn relative to the anterior surface of the body of the upper (L5) and posterior surface of the body of the lower (S1) vertebrae. In norm it is also equal to 0.

The angle of incision (incline) of the sacrum is determined by the intersection of the line tangential to the back surface of the body S1 of the vertical axis. The study is carried out according to an X-ray image taken in an upright position. Normally, the indicator should exceed 30 °.

IM Mitbright (1978) proposed to estimate the magnitude of spondylolisthesis from the angles of displacement of L4 and L5 vertebrae relative to vertebra S1. These angles are formed by the intersection of a vertical line drawn through the geometric center S, the vertebra, with lines connecting the geometric centers of each of these vertebrae to the center of S1.

Determination of the degree of spondylolisthesis according to IM Mitbreakt

Degree of displacement	Offset Angle
	L5	L4
Norm I II III IV V	Up to 45 ° 46-60 ° 61-75 ° 76-90 ° 91-105 ° More than 105 °	Up to 15 16-30 ° 31-45 °

[1], [2], [3]