Lumbar instability

Introduction Lumbar instability is one of the most important diseases in lumbar degenerative diseases. Lumbar instability refers to the pathological changes that occur when the lumbar position is under normal load and cannot maintain the normal positional relationship with each other, and a series of clinical manifestations. The disease occurs in middle-aged males and female obeses. It is not uncommon to see that the most frequent sites are L4-5, followed by L5-S1.

Cause

The most common causes of lumbar instability:

1, degeneration factors: lumbar degeneration is the tissue between the lumbar vertebrae, lumbar intervertebral disc degeneration. When the water content of the nucleus pulposus and the annulus fibrosus decreases, its volume shrinks rapidly, the vertebral body space narrows, and the position between the vertebral body and the surrounding tissue changes, especially the intervertebral disc becomes thinner, and the anterior and posterior longitudinal ligaments can be loosened. The muscles also degenerate. When the trunk is flexed or extended, it is loosened due to the inability to restrict the normal arc motion of the vertebral body, causing the vertebral body to move forward or backward excessively to present a stepwise change in imaging. This activity and change triggers the pain receptors, causing back pain in the patient.

2, iatrogenic causes: paravertebral clusters and other fibrous structures and any anatomical structures of the vertebral segments themselves are structures that maintain the stability of the lumbar spine. Any operation of the lumbar spine will more or less destroy the important tissues of these undetermined lumbar vertebrae, causing vertebral instability.

3, endocrine abnormal factors: endocrine abnormalities (hormone imbalance) easily cause osteoporosis, causing joint ligaments and joint capsule relaxation, reduced elasticity, resulting in instability of the lumbar joints, resulting in low back pain.

4, other reasons: such as family hereditary, metabolic, obese body type, neurogenic and mental factors.

an examination

Related inspection

CT examination of bone and joint and soft tissue

Diagnosis of lumbar instability:

X-ray examination is of great significance for the diagnosis of lumbar instability, especially for dynamic imaging, which can detect vertebral instability before MRI. Regular film also has a certain reference significance.

1. Conventional lumbar X-ray film:

(1) General findings: In the case of lumbar vertebral instability, the main manifestations are: asymmetrical arrangement of small joints, spinous processes, small joint hyperplasia, hypertrophy and subluxation.

(2) Traction spur (traction spur): This spur is generally located in front of or lateral to the vertebral body, protruding horizontally, and the base is about 1 mm from the outer edge of the intervertebral disc. This is due to the abnormal activity of adjacent vertebral bodies when the lumbar vertebrae is unstable, which causes the outer fibers of the intervertebral disc annulus to be subjected to stretched strain. Its clinical significance is also different from the common claw spurs. Small stretch spurs mean lumbar instability, and large stretch spurs only suggest that the segment has been unstable. When the lumbar vertebrae regain stability, the distraction spurs gradually disappear.

(3) Intervertebral space stenosis: Intervertebral space stenosis is a common sign in lumbar disease, which is an indirect basis for nucleus detachment, displacement and degeneration of the entire intervertebral disc. Changes in the facet joints often coincide with stenosis of the intervertebral space, because the narrowing of the intervertebral space increases the pressure on the facet joints and is susceptible to injury and pain.

2. Powerful film:

(1) Overview: The abnormal increase of relative displacement between adjacent vertebral bodies is one of the important manifestations of lumbar instability and the essence of lumbar instability. Clinically, for patients suspected of having lumbar instability, doctors always want to use X-ray examination to find reliable evidence of lumbar instability. However, the general lumbar X-ray film is taken in an upright position when the patient does not perform flexion and extension. Due to the tension of the sacral spine muscle and the rest of the motion segment, the change of the position of the posterior margin of the vertebral body between the degenerative segments is difficult to manifest. In this case, the kinetic observation of the full flexion and extension of the lumbar spine is needed. Continuous improvement in dynamic radiography and measurement techniques contributes to the diagnosis of lumbar instability.

(2) Filming method: First, the remains of the Luscka joint are confirmed on the lumbar X-ray. On the normal motion segment, the position of the Luscka joint remains remains unchanged during the activity; when the motion segments are unstable, their relationship to each other changes. Secondly, it is necessary to have an arch frame of appropriate height and length. The patient is placed on the prone or supine, and the lesion gap is placed at the highest point, so that the psoas muscle can achieve complete flexion and full extension in complete relaxation. When the lumbar vertebral power piece is photographed on the arch frame, since the tibia and the tibia overlap, it is necessary to control the filming conditions. Generally speaking, the center of the tube is horizontally oriented, and the highest point of the arched bracket is injected into the center of the dark, the projection distance is 100 cm, and the exposure condition is 95 kV, 200 ms.

(3) Measurement and calculation of shift value: On the X-ray film, find the segment with abnormal positional relationship between the vertebral bodies. On the next vertebral body, make the connection line A of the posterior superior edge and the posterior lower edge, and then pass the upper line. The posterior superior edge of a vertebral body is the parallel line C of A. The vertical distance between the straight lines A and C is measured, the backward shift is represented by RO, the forward shift is represented by AO, and the sagittal diameter W of the previous vertebral body is measured. Shift value = RO (or AO) / W × 100%, when the supine displacement position value > 9%, or the prone position value > 6%, can help clinical diagnosis of degenerative lumbar instability.

When the lumbar spine is fully flexed, if the position of the Luscka joint remains in the diseased segment is broken, the previous vertebral body slips forward, generally indicating that the disc has only mild degeneration; when the lumbar spine is fully extended, if the lesion is in motion segment The location of the Luscka joint remains ruptured, and the previous vertebral body slips back, generally indicating a moderate or severe degeneration of the intervertebral disc. Adams et al. proposed the concept of dominant damage. They believe that when the lumbar spine is fully flexed, the spine and spine ligaments have the highest tension, while the lumbar spine is fully stretched with the highest tension in the anterior longitudinal ligament. Therefore, when the intervertebral disc is more than moderately degenerated, the former constraint factor - the anterior longitudinal ligament is relaxed. If the lumbar spine is fully extended at this time, the relaxed anterior longitudinal ligament is incapable of limiting the posterior movement of the motion segment, that is, the superior damage of the former constraint.

3. Significance of CT and MRI examination in diagnosis:

(1) Overview: instability of the vertebral body can lead to excessive movement of the facet joints, which can produce wear and reactive bone hyperplasia of the small joints for a long time, and finally osteoarthritis, which reduces the function of restraining the anterior flexion of the vertebral body, Increased instability of the vertebral body. The X-ray film can clearly show the degree of instability of the segmental displacement, and can also show whether the small joints in most cases are symmetrical, with or without hypertrophy, whether the gap is narrow, and whether there is bone spur or osteophyte formation. However, due to the overlapping of bone structures, other pathological signs are often unclear on X-ray films, so CT and MR examinations will play a role.

(2) Diagnostic significance of CT examination: X-ray film can only reflect the two-dimensional structure of the examined part, and CT examination can display the degeneration signs seen by X-ray film in more detail, and can also clearly display Some changes related to nerve root and cauda equina compression, including joint capsule calcification, ligamentum flavum, nerve root canal stenosis, lateral recess stenosis, spinal canal deformation or stenosis, these signs help to explain clinical signs and symptoms and X The problem of line signs does not match. In the diagnosis of traumatic lumbar instability, CT examination can play a more prominent role. Because CT examination can not only show paraspinal hematoma, but also can show the damage of the posterior structure, and can also detect the disorder of tiny bone structure and the interlocking of small joints.

(3) The role of MRI examination: Clinical observations show that MRI examination has the superiority of X-ray plain film and CT examination for the analysis of spinal stability, and can also visually detect the change of spinal cord. CT examination is difficult to display the direct signs such as spinal horn and vertebral spondylolisthesis. Therefore, CT examination is sometimes unreliable in the diagnosis of lumbar instability. MRI examines the advantages of multi-directional imaging and direct display of the spinal cord, making it a special advantage in the evaluation of spinal instability, mainly in the following aspects:

1 Diagnosis and indexing of vertebral spondylolisthesis.

2 to understand whether the spinal canal is narrow and its extent.

3 to understand whether the lumbar vertebrae have scoliosis, angle and direction.

4 shows the degree and extent of intervertebral disc and intervertebral joint degeneration.

5 shows the presence or absence of damage to the spinal cord and its nature and extent.

6 can show the soft tissue around the spine that affects the stability of the spine, and if necessary, can perform the imaging of the spinal dynamics.

On the MRI, the standard of X-ray film can be used, and the analysis of spinal instability can also be performed by the Denis standard.

Differential diagnosis

Symptoms of lumbar instability that are confusing:

In general, lumbar instability is divided into the following three stages:

(1) Early degeneration period: that is, the initial stage of the disease, which is mainly caused by dynamic instability, so it is also called dysfunction period. At this time, the small joint capsule is slightly slack, and the articular cartilage can exhibit early fibrotic changes. At this time, if an external force is applied, the vertebral body may be displaced; but in this period, the clinical symptoms are generally mild, and even if there is an acute symptom, the body can quickly return to normal.

(2) unstable period: As the lesions intensify, the sagging of the small joint capsules is increased, the articular cartilage and intervertebral discs are degenerated, and various clinical symptoms are prone to occur. The vertebral body is abnormally displaced by dynamic imaging. Biomechanical tests have shown that at this stage, unstable segments are most prone to disc herniation.

(3) Fixed period of deformity: With the further development of the lesion, the segmentation of the spine is stabilized due to the formation of the facet joint and the callus around the intervertebral disc. At this time, a relatively fixed deformity appears.

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