The isthmus of the lumbar spine is the narrow part between the upper and lower articular processes, where the bone structure is relatively weak. The normal lumbar spine has physiological anterior convexity and the sacral spine has physiological posterior convexity, and the junction of the lumbar and sacral spine becomes the turning point. The upper lumbar vertebrae are tilted forward, while the lower sacrum is tilted backward, so the negative gravity of the lumbosacral vertebrae naturally forms a forward force, which makes the lumbar 5 have a tendency to slide forward. Under normal circumstances, the force of the lower lumbar 5 articular eminence and the surrounding joint capsule and ligaments can limit this tendency to slip, thus leaving the lumbar 5 isthmus at the intersection of the two forces, and therefore the isthmus is prone to disintegration, which is the reason why the lumbar 5 isthmus disintegrates the most.
After isthmus disintegration, the vertebral arch is divided into two parts: the upper part is the superior articular process, transverse process, vertebral roots, and vertebral body, which still maintain normal connection with the spine above; the lower part is the inferior articular process, vertebral plate, and spinous process, which maintain connection with the sacral spine below. The loss of bony connection between the two parts and the forward displacement of the upper part due to the loss of restriction is manifested by the forward slippage of the vertebral body on the vertebral body below, which is called lumbar spondylolisthesis.
1.Etiology.
Causes include congenital lumbar spondylolisthesis, trauma and strain can also cause lumbar spondylolisthesis. The real cause of lumbar isthmus collapse is still not certain. A great deal of research has been conducted over the years and congenital developmental defects and chronic strain or stress injury have been found to be two possible important causes.
Clinical manifestations.
1. Symptoms.
Those with early lumbar isthmus collapse and lumbar spondylolisthesis do not necessarily have symptoms. Some patients may have lower back pain, which is mostly mild and often intensifies after exertion, or may start due to mild trauma. Most of them improve after taking proper rest or painkillers, so the history of the disease is long. Low back pain is intermittent at first, but later it can be persistent, and in severe cases it affects normal life and cannot be relieved by rest. The pain may also radiate to the sacrococcygeal region, buttocks or the back of the thighs. If it is combined with lumbar disc herniation, it can be manifested as sciatica symptoms.
2.Signs.
Usually there are not many signs, and those with simple isthmic collapse without slippage may not have any abnormal findings. On physical examination, there is only slight pressure pain in the spinous process, interspinous process or paraspinous process. Lumbar movement may be unrestricted or slightly limited. There are no abnormal objective signs in the sacrococcygeal region and other examinations of the buttocks.
In the presence of lumbar spondylolisthesis, there may be a special appearance of forward convexity of the waist, backward convexity of the buttocks, sagging of the abdomen and shortening of the waist, when the spinous processes of the diseased vertebrae protrude posteriorly while the spinous processes above them move anteriorly and are not in the same plane. There may be local depression and an increase in the posterior sacral protrusion. There is pressure pain between the lumbosacral spinous processes, and the dorsal extensor muscles are mostly tense. The lumbar activities are all restricted to different degrees, and the motor and sensory functions of the lower limbs and tendon reflexes are mostly abnormal.
3.Examination.
(1) X-ray film performance:
The diagnosis of this disease and the degree of determination is mainly based on X-ray plain film examination. Anyone suspected of having the disease should routinely take frontal, lateral and left and right oblique films.
(2) CT and MRI examinations:
It can clarify the spinal cord or nerve root compression and assist in differential diagnosis. It is still an essential diagnostic method when differential diagnosis with other diseases or combined with neurological symptoms is necessary.
4, Diagnosis.
The diagnosis of lumbar isthmus collapse and lumbar spondylolisthesis mainly relies on clinical manifestations and X-ray examination. In addition, clinical examination is also required to check for other signs of lower back pain, such as lumbar disc herniation, sprain and strain of the back muscles or ligaments, etc.
5.Treatment:
(1) Non-surgical treatment.
Non-surgical treatment is effective in most cases of slippage within Ⅰ°, including non-steroidal anti-inflammatory painkillers, short-term bed rest, avoidance of heavy lifting and strenuous activities, wearing of braces, and exercise of lumbar back muscles and abdominal muscles. Symptoms can be improved after 6-8 weeks of treatment and are particularly suitable for adolescents who are late in their development. Not every patient with lumbar isthmus crack or spondylolisthesis needs treatment, and a significant proportion of patients with isthmus crack and first-degree lumbar spondylolisthesis are asymptomatic and do not need treatment.
(2) Surgical treatment.
For lumbar pain symptoms persist, or repeated episodes of non-surgical treatment is ineffective, patients are young and middle-aged are feasible for surgical treatment, accompanied by disc herniation, while removing the herniated intervertebral disc nucleus pulposus.
6. Prognosis.
The treatment effect of lumbar arch collapse without peripheral nerve palsy is relatively satisfactory.