Radiologic signs of damage to the ligamentous apparatus of the spine

Radiological signs of damage to the ligamentous apparatus of the spine are proposed, allowing specialists to focus their attention on morphological disorders and compare them with clinical manifestations of injury.

• To avoid the consequences of misdiagnosis, expanded indications for radiography and a high index of suspicion for injury are recommended. Cervical spine imaging should be performed in all patients with localized pain, deformity, crepitus, or swelling in this region, altered mental status, neurologic disorders, head trauma, multiple trauma, or trauma that may damage the cervical spine.
• In case of acute injury, it is recommended to perform the first preliminary film in the lateral position (LP) without pulling the head, even when there are no signs of damage to the atlanto-occipital or atlanto-axial joint, since even minimal stretching in this case can lead to neurological disorders.
• On the lateral projection of the radiograph, the bodies of the cervical vertebrae are arranged in a column, forming four smooth curves, represented by the following structures:
  • the anterior surface of the vertebral bodies;
  • the anterior wall of the spinal canal;
  • the posterior wall of the spinal canal;
  • the tips of the spinous processes.

The first two curves correspond to the directions of the anterior and posterior longitudinal ligaments. The horizontal displacements of the adjacent vertebrae never exceed 3-5 mm. An increase in the distance by 5 mm or more is a deviation from the norm and suggests damage (rupture, stretching) of the ligaments, which leads to instability of the spinal MCL. Similarly, an angle between the cervical vertebrae greater than 11° indicates a rupture of the ligaments, or at least their stretching, which is manifested by a distinct interruption of the smooth lines. The line formed by the tops of the spinous processes is the most irregular of the four, since C ₂ and C ₇ protrude more significantly than the processes of the other vertebrae.

• The normal arrangement of all four curves emphasizes the smooth lordosis. Straightening and some change in this curve is not necessarily pathological. Moreover, in the presence of trauma, when significant muscle spasm may develop or when the patient is in a lying position, the disappearance of lordosis at the cervical level is not of great importance. However, in hyperextension injuries, this sign is pathological.
  
• On lateral radiographs, it is necessary to examine the spaces between the spinous processes. Their significant widening may indicate a stretch (rupture) of the interspinous or supraspinous ligaments (usually as a result of hyperflexion injury).
• The spinous processes are presented as a vertical row located along the midline with approximately equal intervals. An increase in the normal distance between two processes by approximately 1.5 times is considered pathological and may be associated with ligament stretching as a result of hyperflexion injury or blocking of the articular surfaces.
• Functional radiographs (flexion-extension) should be performed only in cases where the stability of the affected PDS is beyond doubt. This examination is absolutely contraindicated in case of PDS instability or neurological disorders. In case of PDS hypermobility, active flexion or extension of the neck should be performed carefully with the patient lying down.
• An underdeveloped cervical spine in children or young people usually predisposes to physiological subluxation in the upper part. As a rule, this is explained by the weakness of the transverse ligament, which results in an increase in the degree of mobility of the atlas relative to the axial vertebra. In this case, the distance between the atlas and the tooth increases to 3-5 mm. A pseudosubluxation between C3 and C4 is also possible _, which _we encountered in our observations.
• Degenerative diseases of the spine are the most common cause of misinterpretation of traumatic injuries. These diseases limit the mobility of the spine at the level of the affected vertebral segment. Increased loads lead to stretching of the ligaments, which "push" the adjacent vertebra forward. Such a subluxation can be misinterpreted as a consequence of hyperextension injury. Therefore, it should be differentiated by the absence of fractures and the presence of a number of other degenerative changes. At the same time, it should be remembered that acute injury can coexist with degenerative changes. Therefore, a chronically affected cervical spine should be carefully examined for injuries.
• An acute rupture of the intervertebral disc will show on radiographs a narrowing of the intervertebral space, a vacuum disc with air accumulation in it, or the disappearance of the normal lordotic curve (in the cervical or lumbar region). The last is the least reliable confirmation of pathology; although it has been shown that depending on the patient's position, the normal arrangement of the lines can change. In various mechanisms of injury, especially in the case of an acute rupture of the disc, signs of instability and/or hypermobility with ligamentous damage are revealed on functional radiographs.

Radiographic signs of damage to the ligamentous apparatus of the spine are significant only if they correlate with the clinical picture. However, important radiographic indicators are:

• narrowing of the anteroposterior diameter of the spinal canal as a result of displacement of the vertebral bodies;
• narrowing of the intervertebral openings (in oblique projection);
• disruption of the apophyseal joints (especially the backward slippage of the superior articular process);
• signs of hypermobility and/or instability of the affected spinal cord.

The latter appears in cases of chronic degeneration due to the spreading weakness of the fixing structures of the spine.

To detect "hidden" displaced vertebral bodies, it is very important to use functional loads in the form of flexion or extension during X-ray examination of the spine. It is extremely important to detect such posterior displacements of the overlying vertebra at the cervical level. When the articular process of the underlying vertebra moves forward, a subluxation occurs. On a lateral image, especially in the position of maximum extension, the anterior sections of the articular process are visible not behind the vertebral bodies, but against the background of the overlying vertebra. The line of the anterior edges of the articular processes appears here not continuous, but stepped. Lateral displacements are also possible, revealed on anteroposterior X-rays.

Classification of injuries of the ligamentous-muscular apparatus of the spine

Degree of damage	Morphological signs of damage
I (mild stretching of the ligamentous-muscular apparatus)	Changes in the echogenicity of the sonographic image are determined: the presence of hypoechoic zones with a length of 1-3 mm
II (moderate stretching of the ligamentous-muscular apparatus)	In the ligamentous-muscular structures, the presence of hypoechoic zones with a length of 4 to 7 mm and corresponding micro-ruptures of these structures are determined.
III (significant stretching of the ligamentous-muscular apparatus)	Characterized by a complete rupture of muscle or ligament structures. A local bulge is scanned - a protrusion of muscle tissue through a fascial defect or the appearance of muscle defects during maximum voluntary contraction corresponding to the rupture. With complete damage to ligament structures, a hypoechoic zone with clear boundaries is visualized
IV (degenerative-dystrophic lesion)	The damage to the ligamentous apparatus is determined in the form of a heterogeneous echogenic picture with inclusions of defects of micro-tears, fraying, and thinning of the tissue.

The occurrence of instability of the upper spine should be assessed depending on the specificity of the injury. For example, atlantoaxial instability can develop only with a rupture of the transverse ligament. The diagnosis is made on the basis of a lateral X-ray. Normally, the distance between the dens and the upper arch of the atlas is within 3 mm. Its increase to 5 mm suggests a rupture of the transverse ligament, a gap of more than 5 mm definitely indicates damage to the transverse and alar ligaments. Suspected injury at this level is a contraindication to performing X-rays with flexion-extension of the neck, since these movements are the basis of the mechanism of neurological damage.

Based on the results of the ultrasound examination, a working classification of ultrasound signs of damage to the ligamentous-muscular apparatus of the spine has been developed for practical healthcare, allowing for the most informative detection of damage or changes to the ligamentous apparatus of the spine already on the 2nd-3rd day after the injury, as well as in the early stages of diseases of the musculoskeletal system (large joints, spine).

As for the place of ultrasonography in the diagnostic process, indications for its use and interpretation of the data obtained in the process of rehabilitation treatment, based on the analysis of the work done, we formulated the following provisions:

• Indications for spinal ultrasonography are all radicular compression syndromes in patients with dorsalgia.
• Ultrasonography is indicated for all patients with reflex pain syndromes who have not achieved a rapid positive effect from the use of traditional rehabilitation therapy regimens.
• In the absence of clinical manifestations during periods of remission, ultrasound examination of the spine can also be performed using the entire range of proposed methods to predict the course of the disease, assess the effectiveness of the course, and, if necessary, confirm the presence of a degenerative process.
• During the treatment process, ultrasonography is used to monitor the effectiveness of the therapy (physical therapy).

The choice of the entire complex of ultrasound methods or individual components is determined depending on the clinical indications (for example, in case of severe radicular pain, it is inappropriate to conduct functional tests) and the technical equipment of the researcher. When sufficient diagnostic information is obtained as a result of using ultrasonography in combination with radiography and additional methods (functional tests, Dopplerography) that coincides with the clinical data, the obtained results are used in treatment planning and the choice of one or another exercise therapy method.