There are many causes of low back pain, such as degeneration of the lumbar spine, infection, deformity, tumor, etc. However, lumbar disc degeneration and secondary pathological changes arising from disc degeneration are undoubtedly the most common causes of low back pain. Humans have been afflicted by low back pain for thousands of years. Low back pain and sciatica are documented in both biblical and Hippocratic texts. Despite this longstanding knowledge, there was never a rational and scientific explanation for low back pain until Mixter and Barr published their classic paper on herniated discs in 1934. These two scholars were the first to explain that the cause of low back pain was a herniated disc in the lumbar spine. Today it is recognized that degenerative changes in the intervertebral discs of the lumbar spine are the source of most low back pain and that “disc herniation” is only one part of this degenerative process.
The key to the importance of a disease in humans is how likely it is to cause death or disability. Degenerative disease of the spine is not a lethal disease in any way, so its importance lies in its prevalence in the population and in the degree of pain and disability that results from it.
Epidemiology
The prevalence of low back pain has been estimated at 53% among those who perform light work, compared to 64% among those who perform heavy work. According to the analysis of statistical data from the UK National Health Insurance, it was found that an average of 13 million working days are lost per year due to low back pain. Low back pain is second only to acute and chronic respiratory disease and coronary heart disease in terms of illnesses that lead to loss of work capacity. This figure is also higher than the number of work hours lost due to strikes in the UK in the 1970s. And in this country, low back pain is the second most common cause of outpatient visits after cold symptoms.
About 80% of adults have experienced definite low back pain. Once low back pain is present, the rate of progression to sciatica is 35%. In addition, after the initial episode has resolved, approximately 95% of the population will experience a recurrence in the future.
The diagnosis of the cause of low back pain is difficult. In 79% of men and 89% of women who first present with low back pain, there is no clear cause. According to the West of Scotland Clinic, which specializes in the treatment of low back disorders, 97% of the 900 patients seen complained of low back pain; 70% had leg pain. Of these leg pain patients, 47% had referred pain (not caused by direct pressure or irritation of nerve roots) and 23% had true radiating pain. one in six (153) of the 900 patients had a definite cause of low back pain, such as tumor, infection, osteoporotic fracture, trauma-induced fracture, and spondylolisthesis. Extra-spinal factors such as retroperitoneal and pelvic pathologies, hip pathologies, peripheral vascular pathologies, and neuronal diseases accounted for 3% of the pain. In addition to these factors, studies have shown that the vast majority of causes of low back pain are disc and small joint pathologies.
Sciatica is a category of pain that has a great impact on individuals and society. Epidemiological statistics show that sciatica occurs in 4.8% of men and 2.5% of women over the age of 35. The average age of onset was 37 years. Seventy-six percent of these patients had experienced symptoms of low back pain an average of 10 years ago. However, not all patients presenting with severe, unilateral sciatica have a poor prognosis: 75% of such patients experience gradual relief of symptoms within 10 to 30 days after the onset of pain, and only about 20% of patients eventually require surgical intervention.
Natural history
The treatment of degenerative lumbar disc disease needs to be based on a thorough understanding of its natural history. Otherwise, neither as a physician nor as a patient can make a proper treatment choice.
In terms of disease progression, low back pain from degenerative disc disease often precedes radiating leg pain, a time frame that averages 6-10 years. Initial low back pain usually starts with an acute attack, and subsequent recurrent attacks gradually tend to become insidious. In contrast, leg radicular pain, whether initial or recurrent, has a more insidious onset.
A study was conducted at the Karolinska Institute in Sweden on a group of 583 patients with initial sciatica, 28% of whom underwent surgery. These surgically treated patients, along with those treated conservatively, were then followed up for 7 years. The results of the study showed that most patients had acute sciatica symptoms for a relatively short period of time, regardless of whether they had surgery or not. The subacute and chronic pain lasted longer and had a greater impact on the patient’s daily life. At the end of follow-up, 15% of patients in the conservative treatment group were partially disabled, limited in their daily activities, and suffered from insomnia. 20% of conservatively treated patients also had significant residual sciatica.
Weber conducted a strictly controlled, prospective study. Two hundred and eighty patients with lumbar disc herniation were included in the study. All herniated discs were confirmed by intravertebral angiography. All patients were initially treated conservatively with a 14-day hospital stay. At the end of these treatments, some patients had symptomatic relief and were excluded from the study. Those patients with sphincter dysfunction and deteriorating neurological function who underwent surgical treatment were also excluded from the study. Instead, those patients with relative indications for surgery were randomly divided into a nonsurgical treatment group and a surgical treatment group for further appropriate treatment. At the 1-year follow-up, the surgical group was found to be significantly more effective than the non-surgical group, as evidenced by significant relief of low back pain and radiating pain, and after 4 years, the non-surgical group began to improve. There was no statistical difference in outcome between the two groups, although there was a trend toward improvement in the surgical group. In Weber’s study, it was also found that 3 months of conservative observation prior to surgical treatment did not result in a decrease in surgical outcomes. Therefore, unless the patient has an indication for acute surgery (e.g. cauda equina syndrome, deteriorating neurological function, etc.), most patients are allowed to be treated conservatively first, a process that lasts at least 2-3 months. With symptomatic treatment such as pain relief, many patients can recover on their own, eliminating the need for invasive treatment. If the symptoms of leg pain persist for more than 12 months before surgical treatment, the effectiveness of surgery is significantly reduced. Perhaps this phenomenon is related to chronic compression leading to nerve ischemia and irreversible degenerative changes.
A thorough understanding of the natural history of low back pain reveals that its overall picture is still positive. Only 14% of patients have low back pain that lasts more than two weeks. However, the recurrence rate of low back pain is also very high, even if the initial symptoms are completely resolved. In an occupational setting, 60% of patients experience a recurrence within 1 year, and the recurrence rate only decreases significantly after 2 years. Sciatica has a relatively long duration, but also resolves spontaneously within 1 month in 50% of patients. The recurrence rate of sciatica is 10% in men and 14% in women.
Treatment of low back pain
Chronic low back pain originating from the intervertebral discs includes disc herniation, intradiscal rupture, and degenerative disc disease. Degenerative lumbar disc disease in turn often progresses to become lumbar spinal stenosis, degenerative lumbar spondylolisthesis, and degenerative lumbar scoliosis.
The goal of lumbar pain treatment is to eliminate or relieve the patient’s pain, improve the patient’s mobility and quality of life. It should be noted that, despite great efforts, the degeneration of the intervertebral discs has so far been irreversible. In other words, although there is lumbar disc degeneration, spinal stenosis, slippage, and scoliosis, if there is no pain or dysfunction there is no need for treatment.
The treatment methods can be summarized into conservative treatment, surgical treatment and biological treatment.
I. Conservative treatment
It is the preferred treatment method for all low back and leg pain. If the low back pain is caused by inflammation, the possibility of making the pain disappear by conservative treatment will be high. Most of the acute low back pain that occurs suddenly is an acute inflammation based on the degeneration of the lumbar spine, and the vast majority will be relieved within 2 weeks.
The methods of conservative treatment are.
1.Bed rest.
2.Physical therapy.
3.Non-steroidal anti-inflammatory and analgesic drugs, muscarinic drugs, etc.
4.Chinese herbal medicine.
5.Make a set of exercise plan suitable for you. After the acute low back pain period, proper exercises are very important. These exercises include.
(1) stretching exercises for the N cord muscle, the stiffness of this part of the muscle will aggravate the tension of the lumbar muscles even more.
(2) Exercises for the lumbar muscles.
(3) aerobic exercises such as walking, swimming, cycling, etc.
II. Surgical treatment
If the pain cannot be relieved by 2-3 months of conservative treatment, or although the pain is not heavy, but the dysfunction is serious, such as the patient cannot sit or stand for a long time, walking is restricted, which seriously affects the patient’s work and daily life, surgery may be required.
There are several other conditions that cannot be treated conservatively for such a long time and require urgent or expeditious surgery. For example, the patient has lower limb paralysis and large and urinary dysfunction due to compression of the cauda equina nerve; or the patient has particularly severe and unbearable pain that cannot be relieved by strong pain medication; or the patient has progressive decrease in muscle strength in the lower limbs due to compression of the lumbar nerve.
The mechanism of lumbar degenerative disc disease triggering lumbar pain and dysfunction is twofold: one is the involvement of nerves (nerve compression); the other is abnormal intervertebral joint function: including intervertebral joint instability, recurrent inflammation, and support function failure. Therefore, the surgical approach is mainly based on decompression and fusion, i.e., decompression of the neural structures and reconstruction of the normal sequence and stability of the intervertebral joints. Spinal decompression and fusion is considered the gold standard for the treatment of lumbar degenerative disc disease.
Decompression methods and fusion methods: they can be performed through different approaches (anterior, posterior medial, posterior lateral) and different modalities (conventional incision, small incision, endoscopic, etc.). The choice of the procedure should be decided according to the patient’s specific situation.
Spinal decompression fusion is also not a perfect and flawless treatment. In addition to the general risks of surgery, there is a certain rate of fusion failure, with an incidence of about 5-10%. A small number of patients may also develop adjacent disc degeneration.
To address these issues, non-fusion techniques have emerged in recent years. Such as disc replacement and interspinous dynamic stabilization techniques (e.g., Dynesys and Wallis systems), which are characterized by the ability to preserve intervertebral joint motion and maintain spinal stability. This method has been used in clinical practice for a relatively short period of time, and its safety and efficacy need to be further observed.
III. Biological therapy
Gene therapy is performed by transfecting the relevant gene into the receptor cells, so that they can stably and continuously express the gene and release the target protein to exert biological effects locally.
Tissue engineering approach is also expected to be a new method for the treatment of degenerative disc disease of the lumbar spine. The construction of tissue-engineered discs to replace degenerated discs may be the most ideal way to treat lumbar DDD. Biological treatment is currently in the experimental stage.