The most important thing to understand is that the definitive cause of an individual’s back pain is difficult to identify. It has been estimated that a definite cause is evident about 20 percent of the time using tests like MRI of the lumbar (lower) spine.
What Causes Back Pain?
There are many structures in the back that may be the cause of the pain. This includes all of the structures in and around the spine that contain nociceptors, which are tiny nerves responsible for transmitting pain. This includes the lumbar discs, the facet joint capsules, the sacroiliac joint, muscles, fascia, vertebral bodies and dura. It also includes abdominal and pelvic structures, such as the uterus, bowels, aorta, kidneys and ureter.
It is common for health care providers to search for the cause of back pain with X-rays, CT scans or MRIs. These tests can be misleading because they may reveal abnormalities that aren’t necessarily causing the pain, leading to unnecessary treatments that are expensive and associated with risks.
One common example is when an MRI reveals a herniated disc in the low back, therefore the patient assumes this is the cause of his back pain. However, we now know that herniated discs seen on an MRI are often not painful. But, once this patient is aware of the herniated disc, he will tend to be more guarded in his actions and see himself in a vulnerable light. These psychological and behavioral alterations can also be a source of pain. Thus, pursuit of the diagnosis can not only be misleading, but can actually contribute to the back pain.
Risk Factors of Back Pain
Because back pain is both common and recurrent, the most important risk factor by far is a previous history of back pain. Other risk factors are much less important and hard to pin down. They may include a family history of back pain, smoking and a job that involves very heavy lifting.
Despite popular belief, the following are not risk factors for back pain: being overweight, degenerative disc disease, the physical pounding of exercise and having a physical job or cumulative damage from a long physical career. It has been my observation that sitting is more destructive than most forms of lifting and carrying.
Acute vs. Chronic Pain
Although the words “acute” and “chronic” suggest that the pain is characterized by its duration, the distinction and meaning has come to signify something more nuanced.
Acute pain is when a pain is sharp for a short period of time, and then the pain goes away either with or without treatment.
Chronic pain is when the pain has been present for more than six months. Also, whatever initiated the pain has either healed or had sufficient time to heal. The reason for the persistence of the pain is difficult to pinpoint, and the role of the brain as the source of persistence is inferred.
There has been an enormous effort in the field of ergonomics to study workplace environments with the hope of modifying them (chairs and desks) to lessen back pain occurrences. In my opinion, however, the best way to reduce back pain at the workplace is not through ergonomics, it’s to improve the overall job satisfaction of the workers because stress is a big contributor to back pain.