”Dad, you’re old, bring a small bench, sit down and rest for a while when you’re tired of walking!” We can often hear, filial children tell their parents this; can also often see the older elderly, is to take a small bench out for a walk, grocery shopping, visit old friends. Young people may look at it and think: how cumbersome ah! However, do not underestimate the small bench, if not it, many older friends would not dare and can not get out of the house. So, why is this? There is a term in medicine: intermittent claudication. It is a person who walks independently for a distance, then weakness, soreness and even numbness in the lower limbs, must rest for a few minutes, the symptoms can be relieved, after which you can continue to walk, but after walking almost the same sing distance, you have to rest again, and this condition occurs repeatedly. This is what spinal surgeons often call a technical term: intermittent claudication. We know that the brain extends down to the spinal cord, which in turn sends out many nerve roots to govern the physiological activities of the entire body. The spinal cord is inside our spine because the spinal cord and the nerve roots that emanate from it are nerve tissue, a very fragile form of tissue that is very important and very vulnerable to injury. The spinal column has a hole in the back of each vertebra from the cervical spine to the sacral spine, and all the holes are connected in a series to form the spinal canal, which houses and protects the spinal cord. The nerve roots from the spinal cord emanate from the intervertebral foramina on both sides of the spine, much like branches from the main trunk of a cable, linking the innervation of various organs. The spinal cord ends at the junction of the thoracic and lumbar vertebrae, and many nerve roots continue downward to form the cauda equina. The cauda equina mainly passes through the lower and middle lumbar spine and into the spinal canal of the sacral spine. The spine is a very special body structure, the backbone of the body, longitudinal trunk, bearing the top and supporting the body, with strong stability; at the same time there is forward flexion, back extension, left and right lateral bending, with great flexibility; and good to protect the spinal nerve. How important and amazing! The flexibility of the spine is due to the fact that the spine is made up of multiple vertebrae, intervertebral discs and small joints connected on both sides; the intervertebral discs are soft tissues that have a certain ability to compress and stretch. Two adjacent vertebrae and the disc in the middle and the small joints on either side make up a functional unit. Let us take one of these functional units, the functional unit between the lumbar 4 and lumbar 5 vertebrae, as an example to illustrate the biological mechanism of intermittent claudication. As we age, the intervertebral discs and small joints gradually age and degenerate, with the disc tissue bulging and squeezing into the spinal canal, the small joint bony hypertrophy pinching into the spinal canal from both sides, the small joint capsule hypertrophy and the ligamentum flavum between the vertebral bodies also hypertrophy and convexity into the main body, eventually forming a narrowing of the spinal canal, compressing the cauda equina nerve and nerve trophoblastic vessels that travel inside. This process is very slow and generally takes decades of gradual aggravation before symptoms are experienced, that is, people gradually start to feel it after they are in their 50s or 60s. The stenosis gradually worsens, as does the nerve damage, and the symptoms described at the beginning of this article appear after a period of self-supported walking. At the beginning of the symptoms, it is possible to walk 1000 meters before rest is needed, gradually increasing to 800 meters, then 600 meters, 500 meters ……, the shorter the continuous walking distance, the more severe the spinal stenosis and the more severe the nerve damage. Some people ask: Why can I walk again after sitting down and resting for a while? The reason is that the degree of spinal stenosis is more severe when walking independently, and when sitting down, squatting or even bending, the hypertrophic ligaments between the vertebrae are briefly stretched and thinned, which in turn briefly relieves the degree of stenosis and nerve damage, and after the nerves are relieved, you can continue to walk, but soon after rest. In severe cases, people need to rest after walking 50 meters, 10 meters, or even 5 meters. Imagine the quality of life if you had to rest every 10 meters! Of course, spine surgeons will not allow such a serious situation to arise. Generally speaking, those who need to rest at 800 meters should receive conservative medication, those who need to rest at 500 meters should receive surgery, and those who need to rest at 50 meters and below should receive surgery as soon as possible. Intermittent claudication is often accompanied by symptoms such as lumbar and leg pain, limb numbness, muscle atrophy, and even cauda equina symptoms such as abnormal sensation in the perineum and dysfunctional bowel movements. The appearance of cauda equina symptoms is a sign that emergency surgery is needed!