Lower back pain is the most common reason for orthopedic clinical consultation. In terms of terminology, lower back pain belongs to the category of symptomatology, and its actual reference is a generic term for a group of diseases with low back pain as the fundamental clinical manifestation, excluding lumbar spine diseases with other clinical manifestations such as disc herniation, spinal stenosis, and lumbar spondylolisthesis. Lower back pain is an important disease affecting human health and is a major cause of increased health care expenditures, absenteeism, and disability (somatic and psychological factors), becoming a socioeconomic issue of great concern. The literature reports that the annual incidence of lower back pain in adults is 15-45%, and more than 70% of adults suffer from lower back pain in their lifetime, with the incidence in men being 73% and in women 88%. The causes of lower back pain are numerous, the pathogenesis is complex, and the clinical management is difficult, so orthopedic surgeons inevitably have the lament that “patients have back pain, doctors have headaches”.
I. Definition of lower back pain
In terms of pain location, lower back pain is distributed in the anatomical region of the lumbar or sacral region. According to the duration of symptoms, it is divided into: acute pain ≤ 3 months; chronic pain ≥ 3 – 6 months and episodic pain, etc. The description of lower back pain should include: pain characteristics (intensity, duration, frequency of episodes); specific or nonspecific diagnosis; physical and functional status; general characteristics such as gender and age and treatment history.
Methods of evaluation of low back pain include.
1. self-report, which is considered the gold standard for pain evaluation because it can reflect the pain characteristics truthfully but with some subjectivity, such as visual analog scoring (VAS), which is simple and easy to use and does not require verbal description.
2, Questionnaire method MPQ , scored from emotional, sensory and evaluative aspects, mainly used in clinical studies.
3, Pain drawing, drawing the pain area and intensity, etc. It also includes physical and functional tests, etc.
2.Risk factors of lower back pain
There are many risk factors for lower back pain, which can be divided into three main areas as follows.
1.Personal factors.
① Age, 35 – 55 years old is the good age for lower back pain. As age increases, degeneration of intervertebral discs and small joints is inevitable, while the decrease in muscle strength and ligament strain of the low back muscles seriously affects the stability of the spine, making it prone to lower back pain.
②Health condition, it is generally believed that healthy people with strong limbs, especially trunk muscles, good spinal stability and good mental condition are relatively less likely to have chronic lower back pain.
(iii) Deformities, patients with kyphosis, scoliosis and unequal lower limbs have decreased trunk balance. Because to maintain relatively good posture and gait, it is necessary to compensate functionally through the spine and lumbar back muscles, which results in spinal degeneration and lumbar muscle strain causing lower back pain.
2.Occupational factors.
① heavy physical labor, the occurrence of lower back pain is related to the engagement in heavy physical labor. the results of Matsui et al. investigation showed that the occurrence of lower back pain is positively correlated with the intensity of physical labor.
② Frequent bending and twisting, occupations that require frequent bending and twisting, such as pushing, pulling and lifting heavy objects, can accelerate disc and small joint degeneration and lumbar muscle and ligament strain, producing lower back pain.
③ Repetitive work, not only will accelerate intervertebral disc, small joint and ligament strain, but also because of repeatedly doing the same action, easy to cause muscle fatigue, especially the lumbar back muscle, weakening its role in the stabilization of the spine, lower back pain.
④ Stationary posture, the size of the load on the lumbar spine is related to the body position. The incidence of lower back pain is generally higher in occupations that require a long sitting or standing position. If in sitting or standing position for more than 2 hours, the occurrence of lower back pain increases significantly. This is due to the greater load on the lumbar region in this position, and the intervertebral discs and posterior ligaments are prone to strain; in addition, the lumbar back muscles need to be involved to maintain this position, and the contraction of the lumbar back muscles for a long time will become fatigued and more prone to lumbar pain. Some studies believe that drivers are prone to low back pain and its long-term sitting position.
3, psychological and social factors.
With the development of society, the influence of psychological and social factors on the development of chronic lower back pain is receiving increasing attention. Psychological tests have become part of the functional examination of the lumbar spine, because individuals with psychological abnormalities are prone to non-organic lower back pain, and also because these patients suffer from long-term pain, pain makes them mentally fragile, lose confidence in treatment, generate apprehension and fear, and even exaggerate symptoms and increase pain. In addition, social factors are also an important factor affecting the occurrence of chronic lower back pain. It is generally believed that the psychological stress caused by work and life environment is related to the occurrence of lower back pain. Some scholars have reported that the incidence of lower back pain is 2.5 times higher in those who are dissatisfied with their occupation than in those who are satisfied, and the relationship with supervisors and colleagues is also significantly associated with the occurrence of lower back pain. Some studies have also confirmed that work monotony, long hours, and high concentration may also be related to the occurrence of lower back pain.
Third, the source of lower back pain
The cause of lower back pain has also been a long-standing subject of exploration. In the 1930s, lumbar disc herniation was recognized and established, and since then nerve compression has been considered the main cause of low back pain. As research has evolved, the intervertebral discs, small joints and sacroiliac joints are considered to be the main potential sources of pain, in addition to soft tissue sources such as muscles, fascia and ligaments and referred pain and non-organic pain (somatic symptomatization due to psychological factors). The incidence of the first three accounts for 39%, 15% and 13% respectively. All the above structures are innervated, and when the injury receptors are subjected to harmful, mechanical and chemical stimuli, pain will be produced.
IV. Diagnosis and treatment principles of lower back pain
There is no unified standard for the diagnosis of lower back pain, and the main reference standard is anesthesia or excitation injection, but there are invasiveness, cost problems and operability, so it is not routinely used in clinical practice.
History taking should include.
① the nature of the pain.
② the site of pain.
③ The degree of pain.
④ the presence or absence of previous attacks.
⑤ duration of pain.
(vi) the presence of gastrointestinal, pelvic or urinary symptoms.
⑦ Any accompanying psychiatric symptoms.
In addition to medical history and physical examination, commonly used auxiliary examinations include
X-ray: enables direct observation of bony structures of the lumbar spine, such as infections, tumors, slippage and other lesions, and reflects some indirect signs such as narrowing of the spinal space and soft tissue swelling.
myelography: an invasive test that allows for the definitive diagnosis of spinal canal occupancy, spinal stenosis and other diseases
CT: mainly reflects bony structural changes, spinal canal morphology, bone destruction, etc.
MRI: no radiation damage, can be imaged in multiple directions, and is sensitive to soft tissues such as intervertebral discs and nerve structures, but expensive.
Treatment for lower back pain should vary from person to person, with the goal of returning to work as soon as possible. For acute lower back pain, cure can be achieved through appropriate bed rest and symptomatic treatment. In contrast, the treatment of chronic lower back pain is the most difficult, and in addition to symptomatic treatment, long-term lumbar and abdominal muscle exercise and psychological treatment are needed to cooperate.
1.General treatment.
① Bed rest.
② anti-inflammatory and analgesic agents, muscle relaxants.
③Physiotherapy, massage.
④Closure therapy.
⑤ Traction, etc.
2.Functional exercise
Functional exercise plays an important role in the treatment of chronic lower back pain, and its main purpose is to strengthen the trunk muscles and enhance the stability of the spine. The lumbar spine is located in the middle of the trunk and is the hub of spinal movement, and its stability directly affects spinal activities and the occurrence of lower back pain. At rest, the stable structure of the spine is mainly the intervertebral discs, small joints and posterior ligamentous structures, while the dynamic stable structure during movement is mainly the lumbar back muscles. Lumbar back muscle exercise can greatly reduce the tension of the posterior ligaments, enhance the stability of the spine, thus avoiding or reducing the ligaments and intervertebral disc strain, and effectively prevent and treat lower back pain; at the same time, lumbar back muscle exercise can also promote the blood circulation of muscles and their fascia, which is conducive to the elimination of acidic metabolites of muscles, eliminate muscle fatigue and myofascial inflammation, and relieve the symptoms of lower back pain. In addition, the support role of the abdominal cavity on the spine is also very important. Keeping the chest straight waist posture, can make the abdominal muscles have a certain tension, and abdominal muscle exercise and make the abdominal muscles have a certain muscle strength, reduce the load on the spine, to prevent and control lower back pain. Others believe that aerobic exercise to enhance the adaptability and endurance of people is also important for the prevention and treatment of lower back pain.
3.Lumbosacral support
Lumbar apron is the most common tool used by orthopedic surgeons to treat lower back pain. Wearing a lumbar brace can not only relieve muscle spasm and reduce symptoms through its braking and protective effects, but also maintain or increase abdominal pressure and share the spinal load, which can help prevent and treat chronic lower back pain. Therefore, if used properly, wearing a lumbar brace can reduce or cure lower back pain. However, effective lumbar and abdominal muscle exercise must be carried out at the same time, and make it a “muscle brace”, otherwise there will be disuse muscle atrophy, aggravating the lumbar instability.
4.Labor protection
The occurrence of lower back pain is related to the stability imbalance of the spine. To maintain the stability of the spine, in addition to intervertebral discs, small joints, muscle ligaments and other structures, it is very important to maintain good posture. People in a standing position for a long time have deepened lumbar convexity, which increases the pressure on the small joints and intervertebral discs and can cause lower back pain. If you can adjust the posture, so that the hip and knee joints are lightly flexed, the body slightly forward, so that the lumbar load will be reduced, the occurrence of low back pain is also reduced. In the sitting position, especially when sitting forward, the pelvis is tilted back, the body’s center of gravity is shifted forward, and the spinal bending moment is increased, which increases the load on the intervertebral discs and the posterior ligaments, easily causing lower back pain. If you can take an upright sitting position, so that the pelvis is tilted forward, the lumbar load will be reduced. If the chair has armrests, backrest, not only the influence of upper limb gravity is reduced, but also because the lumbar back has to rely on, the load is also reduced, the occurrence of lower back pain is also greatly reduced.
Lifting heavy objects is an external load, the impact of its load on the spine, in addition to the weight, size and shape of the object, but also with the degree of lumbar flexion. When using the knee bending method of lifting objects, due to the forward tilt of the trunk, lumbar flexion, lengthening of the force arm, lumbar spine load is the largest, easy to cause lumbar strain injury, while using the knee bending straight waist method of lifting objects, because the object is closer to the spine, and rising activities are mainly dispersed in the lower limb joints, spinal load and strain injury is reduced.
5.Education and training
Some people advocate the establishment of a “low back pain school”, adopting individual counseling or group classes with video for education. The learning content includes: ① knowledge of relevant anatomy; ② what posture and position is most beneficial; ③ the danger of persistent pain; ④ the causes of low back pain and treatment methods. The focus of the training is to strengthen the muscle strength and endurance exercise, and to instruct them to adopt reasonable posture and healthy behavior.
The focus of training is to strengthen the muscle strength and endurance exercise, and to instruct them to adopt reasonable posture and healthy behavior.
6.Psychological treatment
For patients with chronic lower back pain who have psychological abnormalities, their treatment requires the collaboration of physicians, physical therapists and psychologists to carry out multi-faceted functional rehabilitation training. Therefore, if the patient is ineffective with surgery or other treatments, psychological tests should be conducted promptly to clarify the diagnosis. In the treatment, the role of psychological factors in the development of chronic lower back pain should be fully understood, and close communication with the patient should be made to gain the patient’s trust and cooperation; it should also be explained to the patient that there are no tissue structure patients and that the pain is mainly due to the organismal changes caused by emotional tension. It is believed that those who are optimistic about treatment and have high expectations have better outcomes. Treatment with antidepressants can also be used when necessary. In addition, for the psychological abnormalities caused by life stress or work environment, corresponding measures should also be taken to improve. In conclusion, optimism, healthy and reasonable demeanor, and regular exercise are extremely important to maintain physical health and prevent chronic lower back pain.
7.Surgical treatment
Surgery is mainly suitable for those who have no conservative treatment, exclude psychological factors, and have organic damage in tissue structure.
V. Intervertebral discogenic pain
Discogenic pain is one of the most popular studies in spinal surgery in recent years. First described by Crock et al, its main pathological feature is a tear of the annulus fibrosus, and it is the most common type of chronic lower back pain. It is the most common type of chronic lower back pain. The currently accepted definition is: lower back pain caused by the disc itself, except for chronic low back pain with nerve root compression on imaging, i.e. discogenic lower back pain. The basis for understanding discogenic lower back pain is to identify the distribution and function of the nerves within the disc.
(1) The intervertebral disc is composed of the nucleus pulposus, the fibrous ring and the cartilage plate. The posterior portion of the annulus fibrosus is innervated by the sinus nerve, while the lateral and anterior portions of the annulus fibrosus are innervated by branches from the anterior spinal nerve and sympathetic nervous system.
(2) Crock believes that degeneration of the nucleus pulposus of the lumbar intervertebral disc leads to imbalance in the distribution of stress in the annulus fibrosus and tearing of the inner annulus fibrosus as the pathological basis of the disorder within the lumbar intervertebral disc. After the rupture of the inner fibrous ring, nerve fibers, blood vessels and granulation tissues invade the fissure for repair. The sinus nerve endings invading the inner layer of the fibrous ring are mostly unmyelinated fibers, exposed in the interstitial fluid, so they are susceptible to intrainterstitial chemicals (such as SP, CGRP, VIP) and mechanical changes, and discogenic lower back pain occurs. It was found that the density of nerve fibers in the outer fibrous annulus of the diseased disc was significantly higher than that of the normal disc, and 80% of the inner fibrous annulus of the diseased disc had nerve distribution, further demonstrating this pathogenesis.
(3) Suseki used CGRP immunohistochemistry to demonstrate that the L5S1 disc in rats is innervated by the dorsal root ganglion of L1-2 through the paravertebral sympathetic trunk, which is connected to the sinus vertebral nerve through the gray traffic branch. Therefore, it can be suggested that the sympathetic distribution of the lumbar discs should be associated with L2 or higher segmental planes, and clinically discogenic lower back pain is also mainly manifested in the L1-2 cutaneous innervation area, manifesting as pain in the lower back, buttocks, inguinal region, and lateral thighs, and abnormal sensation in these areas.
Discogenic pain with or without involvement pain usually lacks objective neurological signs and is difficult to determine on clinical examination. The lumbar discs are normal in appearance, there is no lumbar disc herniation, and x-rays and CT scans are normal. It is often secondary to significant trauma and complains of deep pain in the lower back medially, relieved by rest and aggravated by activity, with insignificant lower extremity signs and symptoms, rarely involving the subacromial knee. MRI shows high signal zone (HIZ), disc degeneration, endplate changes, rupture of the annulus fibrosus and narrowing of the intervertebral space, suggesting the presence of discogenic back pain to varying degrees, especially the black disc, which is thought to be closely related to discogenic pain. MRI abnormalities are also common in asymptomatic people, and Modic et al. found that nearly 30% of normal individuals had abnormal MR I signal intensity changes. Thus, MRI plays an important, but not definitive, role in the diagnosis of discogenic lower back pain. Vibration testing is simple to perform and has diagnostic value in combination with MRI for discogenic pain. Discography: It is the most important diagnostic method and gold standard for discogenic low back pain. Its evaluation criteria include four parts: morphology of the disc being injected, intra-disc pressure and/or volume of fluid receiving the injection, patient’s subjective response to the injection, and lack of pain response in adjacent discs. A normal disc can receive 0.3 – 1.0 ml of fluid volume, and the peak intradiscal pressure should be 400 – 500 Kpa. pain intensity, pain replication, and pain behavior of the patient are described by imaging, and there is no pain response in normal adjacent discs. However, the test is invasive and performed under x-ray fluoroscopy.
Good treatment of degenerative disc disease must be predicted based on the natural history of the disease, and the natural history of discogenic lower back pain is poorly understood. Most episodes of acute lower back pain rarely last more than 2 weeks, and only 7% of patients with lower back pain become chronic, of which only 1/3 will develop chronic disabling lower back pain, requiring further examination of the condition. The findings suggest that discogenic lower back pain may be a self-limiting condition and that symptoms may decrease with increasing age, lumbar stiffness and degenerative changes throughout the lumbar spine.
Non-surgical approaches to the treatment of lower back pain include bed rest, exercise, traction, acupuncture, transcutaneous electrical stimulation, bracing, biofeedback, medication, and massage. Patients with discogenic lower back pain should be treated non-operatively for at least 3 months with non-steroidal anti-inflammatory medications, muscle relaxants and physical rehabilitation procedures. Physical rehabilitation procedures include warm water therapy, aerobic swim therapy, and isometric trunk muscle exercises. Patients who do not complete the rehabilitation program should undergo psychological testing and outpatient pain management. Those who have completed the 3-month rehabilitation program with pain relief should have a functional assessment before returning to work. If lower back pain is still present after completing the rehabilitation program, surgical treatment may be considered.
Fusion surgery is preferred for surgical treatment of discogenic lower back pain. Although other methods, such as discectomy, percutaneous discectomy, and papaya clotting protease myelolysis, have been reported for the treatment of discogenic lower back pain, the efficacy of these methods has not been confirmed. Artificial disc replacement and artificial nucleus pulposus replacement are still in the initial stage, and the long-term efficacy remains to be observed. Discectomy and interbody fusion may be the most effective treatment for discogenic lower back pain. The mechanism is twofold: one is the removal of the source of pain, and the other is the elimination of segmental motion. There are currently three main types of surgical fusion: anterior fusion, posterior fusion, and combined anterior and posterior fusion. Saal et al. reported the first clinical results of intradiscal electrothermal therapy (IDET) for the treatment of discogenic lower back pain in 2000, which has attracted the attention of the international spine surgery community. IDET is a minimally invasive therapy for discogenic lower back pain that has developed rapidly in recent years and has been clinically proven to be effective. A certain level of heat causes collagen fibers to contract and coagulate nerve fibers. When the tissue is heated to a certain temperature (60–65 degrees) during IDET, the covalent bonds that maintain the triple helix structure of the collagen fibers break, the collagen molecules contract and thicken, and the fibrous ring fissures are reconnected and reinforced, thus improving the biomechanical state of the fibrous ring and increasing the stability of the spinal motion segments; in addition, the heat energy The initial clinical efficacy of IDET is encouraging, as it provides a minimally invasive treatment for refractory discogenic lower back pain. Compared with disc fusion, IDET has obvious advantages, such as minimally invasive, low cost, significant efficacy, and few complications, and is a better treatment option for patients with discogenic lower back pain that occurs in adjacent segments after multi-gap or intervertebral fusion, especially. The clinical efficacy of IDET has yet to be rigorously evaluated. Basic research on the biological treatment of discogenic low back pain is also underway, including gene therapy and stem cell transplantation for the purpose of regenerating intervertebral disc function.
Sixth, small joint-derived pain
The small joints of the lumbar spine are the important joints of the spinal connection, which have the function of limiting the forward flexion and forward movement of the spine and resisting various forms of load such as compression, shear and rotation. Trauma, abnormal stress and other factors can lead to degeneration and injury. The small joints, or synovial joints, are synovial joints with a rich distribution of nerve endings on the synovial surface and joint capsule that sense and transmit pain information. Pathogenesis: damage and inflammation of articular cartilage; loss of function of small joints secondary to intervertebral disc degeneration, causing progressive structural instability of column segments, accelerating degeneration and hyperplasia of small joints, and compression and stimulation of nerve roots causing pain. Clinical manifestations: lack of specificity, pain mainly located in the lower back above the gluteal crease, with or without involvement pain, and deep pressure pain at the small joints.
CT can reveal hypertrophy, hyperplasia, sclerosis of the articular prominence, unevenness of the articular surface, cystic changes of the subchondral bone, vacuum in the joint cavity, joint subluxation and narrowing of the lateral saphenous fossa caused by osteophytes in the small joints; MRI shows compression of the spinal canal and nerve root canal by the hyperplastic small joints, edema of the joint capsule, protrusion of soft tissue in the joint capsule and changes of the synovial membrane in the joint cavity. MRI shows compression of the spinal canal and nerve root canal by hyperplastic small joints, edema of the joint capsule, soft tissue protrusion in the joint capsule and synovial changes in the joint cavity. Small joint block is the gold standard for the diagnosis of lower back pain of small joint origin. The efficacy of the drug is judged by matching the time of pain relief to the time of action of the local anesthetic. However, this test is invasive and may increase the chance of infection, and it cannot be used in patients who are allergic to local anesthetics.
In addition to the conventional treatment for low back pain, the treatment is intra-articular injection, small joint medial nerve branch block, medial branch nerve degeneration and destruction (physical, chemical, surgical), etc.
VII. Sacroiliac joint-derived pain
The sacroiliac joint is a micromotor joint with strong ligaments, muscles and fascia working together to fix and limit joint movement and maintain joint stability to conduct and balance stresses from the trunk to the lower extremities. Common pathological changes in the sacroiliac joint include deformity, injury, strain, degeneration, and inflammation. Pain below the fifth lumbar vertebra, which may be accompanied by radiating pain, lacks specificity. Clinical examination and bone scan can be helpful for diagnosis. intra-sacroiliac joint closure under X-ray fluoroscopy is generally diagnosed as sacroiliac joint-derived lower back pain if the patient’s pain is relieved by 75% within 15–45 minutes after injection, which is the most reliable and effective method. If non-surgical treatment is ineffective, sacroiliac joint fusion can be considered.
VIII. Muscle-derived pain
The paravertebral muscle group of the spine is the dynamic stabilizing structure of the spine, maintaining the upright posture of the body. Skeletal muscle fibers include type I and type II, of which type I fibers contract slowly, contraction lasting fatigue resistance, strong anti-gravity effect, is important to maintain the body’s physiological posture and complete certain fine activities; type II fibers contract quickly, easy fatigue, strong resistance effect, is important to complete the body’s fast and gross movement. Therefore, the predominance of type I fibers in the lumbar back muscle is compatible with its function. Patients with lower back pain are often accompanied by decreased muscle strength or endurance of the low back muscles. Long-term seated work with little activity can cause disuse atrophy of the paravertebral muscles. Studies have shown that the paravertebral muscle has a small percentage of type I fibers, a small cross-sectional area, and a reduced resistance to fatigue.
The contraction of the sacrospinous muscle resists the forward flexion moment, and when the lumbar back muscles are fatigued, the sacrospinous muscle function is weakened, thus subjecting the intervertebral discs and ligaments to greater stress and making them susceptible to injury. Muscle fatigue its coordination and control decreases, the dynamic stability of the lumbar spine decreases, the lumbar spine is overactive, and the lumbar spine is unstable. Low back pain causes protective spasm of the paravertebral muscles and reduced activity, which aggravates the easy fatigue of the paravertebral muscles, forming a vicious cycle that may be one of the reasons for the delay in healing and recurrent attacks of lower back pain.
In addition, paravertebral myofascial spacer syndrome is considered to be the pathogenesis of myogenic low back pain. Increased pressure within the osteofascial compartment due to various causes and muscle ischemia produce chronic low back pain. Clinical decompression by osteofascial compartment dissection can relieve or eliminate pain, which laterally confirms the existence of this etiology.
IX. Conclusion
Low back pain is a global medical and socioeconomic problem that deserves the attention of both doctors and patients as well as public institutions in society. The general public can prevent the occurrence of low back pain by acquiring relevant knowledge and information through health education, vocational training, and labor protection. The knowledge of low back pain patients about their disease can help to improve the effectiveness of treatment and early recovery. For their part, doctors should continue to improve their awareness and pay enough attention to low back pain as a common disease for the benefit of their patients.