Low back pain or lumbago is a common disorder involving the muscles, nerves, and bones of the back, in between the lower edge of the ribs and the lower fold of the buttocks. Pain can vary from a dull constant ache to a sudden sharp feeling. Low back pain may be classified by duration as acute (pain lasting less than 6 weeks), sub-acute (6 to 12 weeks), or chronic (more than 12 weeks). The symptoms of low back pain usually improve within a few weeks from the time they start, with 40–90% of people recovered by six weeks.
In most episodes of low back pain a specific underlying cause is not identified or even looked for: the pain is believed to be due to mechanical problems such as muscle or joint strain. If the pain does not go away with conservative treatment or if it is accompanied by "red flag" symptoms such as unexplained weight loss, fever, or significant problems with feeling or movement, further testing may be needed to look for a serious underlying problem. In most cases, imaging tools such as CT scans are not useful or recommended for low back pain that lasts less than 6 weeks (with no red flags) and carry their own risks. Some low back pain is caused by damaged intervertebral discs, and the straight leg raise test is useful to identify this cause. In those with chronic pain, the pain processing system may malfunction, causing large amounts of pain in response to non-serious events. Chronic non-specific low back pain is a highly prevalent musculoskeletal condition that not only affects the body, but also a person's social and economic status. Chronic non-specific low back pain is affected by psychosocial factors and unhealthy lifestyles and habits, in addition to musculoskeletal issues.
Normal activity should be continued as much as the pain allows. Initial management with non-medication based treatments is recommended. Non–medication based treatments include superficial heat, massage, acupuncture, or spinal manipulation. If these are not sufficiently effective, NSAIDs are recommended. A number of other options are available for those who do not improve with usual treatment. Opioids do not significantly reduce acute or chronic back pain and are not recommended in chronic low back pain due to the lack of benefit and risks of harm. Opioids carry a risk of side effects such as high rate of addiction, accidental overdose and death. Surgery may be beneficial for those with disc-related chronic pain and disability or spinal stenosis. No clear benefit of surgery has been found for other cases of non-specific low back pain. Low back pain often affects mood, which may be improved by counseling or antidepressants. Alternative medicine therapies do not carry enough evidence to recommend them. The evidence for chiropractic care and spinal manipulation is mixed.
Approximately 9–12% of people (632 million) have low back pain at any given point in time, and nearly 25% report having it at some point over any one-month period. About 40% of people have low back pain at some point in their lives, with estimates as high as 80% among people in the developed world. Low back pain is the greatest contributor to lost productivity, absenteeism, disability and early retirement worldwide. Difficulty with low back pain most often begins between 20 and 40 years of age. Women and older people have higher estimated rates of low back pain and also higher disability estimates. Low back pain is more common among people aged between 40 and 80 years, with the overall number of individuals affected expected to increase as the population ages. According to the World Health Organization in 2023, low back pain is the top medical condition world-wide from which the most number of people world-wide can benefit from improved rehabilitation.
Signs and symptoms In the common presentation of acute low back pain, pain develops after movements that involve lifting, twisting, or forward-bending. The symptoms may start soon after the movements or upon waking up the following morning. The description of the symptoms may range from tenderness at a particular point, to diffuse pain. It may or may not worsen with certain movements, such as raising a leg, or positions, such as sitting or standing. Pain radiating down the legs (known as sciatica) may be present. The first experience of acute low back pain is typically between the ages of 20 and 40. This is often a person's first reason to see a medical professional as an adult. Recurrent episodes occur in more than half of people with the repeated episodes being generally more painful than the first.
Other problems may occur along with low back pain. Chronic low back pain is associated with sleep problems, including a greater amount of time needed to fall asleep, disturbances during sleep, a shorter duration of sleep, and less satisfaction with sleep. Chronic low back pain is also associated with depression and anxiety.
Causes
Low back pain is not a specific disease but rather a complaint that may be caused by a large number of underlying problems of varying levels of seriousness. The majority of low back pain does not have a clear cause, but is believed to be the result of non-serious muscle or skeletal issues such as sprains or strains or muscle spasms. About 90% of actue low back pain is nonspecific. Obesity, smoking, weight gain during pregnancy, stress, poor physical condition, and poor sleeping position may also contribute to low back pain. There is no consensus as to whether spinal posture or certain physical activities are causal factors. A full list of possible causes includes many less common conditions. Physical causes may include osteoarthritis, degeneration of the discs between the vertebrae or a spinal disc herniation, broken vertebra(e) (such as from osteoporosis) or, rarely, an infection or tumor of the spine.
Women may have acute low back pain from medical conditions affecting the female reproductive system, including endometriosis, ovarian cysts, ovarian cancer, or uterine fibroids. Nearly half of all pregnant women report pain in the low back during pregnancy, which is attributed to changes in posture and the relocation of the center of gravity, leading to strain on the musculoskeletal system, including muscles, ligaments, and joints.
Low back pain can be broadly classified into four main categories: Musculoskeletal – mechanical (including muscle strain, muscle spasm, or osteoarthritis); herniated nucleus pulposus, herniated disc; spinal stenosis; or compression fracture Inflammatory – HLA-B27 associated arthritis including ankylosing spondylitis, reactive arthritis, psoriatic arthritis, inflammation within the reproductive system, and inflammatory bowel disease Malignancy – bone metastasis from lung, breast, prostate, thyroid, among others Infectious – osteomyelitis, abscess, urinary tract infection.
Pathophysiology
Back structures
The lumbar (or lower back) region is the area between the lower ribs and gluteal fold which includes five lumbar vertebrae (L1–L5) and the sacrum. In between these vertebrae are fibrocartilaginous discs, which act as cushions, preventing the vertebrae from rubbing together while at the same time protecting the spinal cord. Nerves come from and go to the spinal cord through specific openings between the vertebrae, receiving sensory input and sending messages to muscles. Stability of the spine is provided by the ligaments and muscles of the back and abdomen. Small joints called facet joints limit and direct the motion of the spine.Floyd, R., & Thompson, Clem. (2008). Manual of structural kinesiology. New York: McGraw-Hill Humanities/Social Sciences/Languages.
The multifidus muscles run up and down along the back of the spine, and are important for keeping the spine straight and stable during many common movements such as sitting, walking and lifting. A problem with these muscles is often found in someone with chronic low back pain, because the back pain causes the person to use the back muscles improperly in trying to avoid the pain. The problem with the multifidus muscles continues even after the pain goes away, and is probably an important reason why the pain comes back. Teaching people with chronic low back pain how to use these muscles is recommended as part of a recovery program.
An intervertebral disc has a gelatinous core surrounded by a fibrous ring. When in its normal, uninjured state, most of the disc is not served by either the circulatory or nervous systems – blood and nerves only run to the outside of the disc. Specialized cells that can survive without direct blood supply are in the inside of the disc. Over time, the discs lose flexibility and the ability to absorb physical forces. This decreased ability to handle physical forces increases stresses on other parts of the spine, causing the ligaments of the spine to thicken and bony growths to develop on the vertebrae. As a result, there is less space through which the spinal cord and nerve roots may pass. When a disc degenerates as a result of injury or disease, the makeup of a disc changes: blood vessels and nerves may grow into its interior and/or herniated disc material can push directly on a nerve root. Any of these changes may result in back pain.
Pain sensation Pain erupts in response to a stimulus that either damages or can potentially damage the body's tissues. There are four main stages: transduction, transmission, perception, and modulation. The nerve cells that detect pain have cell bodies located in the dorsal root ganglia and fibers that transmit these signals to the spinal cord. The process of pain sensation starts when the pain-causing event triggers the endings of appropriate sensory nerve cells. This type of cell converts the event into an electrical signal by transduction. Several different types of nerve fibers carry out the transmission of the electrical signal from the transducing cell to the posterior horn of spinal cord, from there to the brain stem, and then from the brain stem to the various parts of the brain such as the thalamus and the limbic system. In the brain, the pain signals are processed and given context in the process of pain perception. Through modulation, the brain can modify the sending of further nerve impulses by decreasing or increasing the release of neurotransmitters.
Parts of the pain sensation and processing system may not function properly; creating the feeling of pain when no outside cause exists, signaling too much pain from a particular cause, or signaling pain from a normally non-painful event. Additionally, the pain modulation mechanisms may not function properly. These phenomena are involved in chronic pain.
Diagnosis As the structure of the low back is complex, the reporting of pain is subjective, and is affected by social factors, the diagnosis of low back pain is not straightforward. While most low back pain is caused by muscle and joint problems, this cause must be separated from neurological problems, spinal tumors, fracture of the spine, and infections, among others. The ICD 10 code for low back pain is M54.5.
Classification