Non-Specific Lower Back Pain
What is non-specific low back pain?
Non-specific low back pain is the diagnosis for people who have pain in the lumbar region, but the specific source of pain is not or has yet to be identified. It's estimated to account for about 90% of low back pain cases. Some individuals will seek a diagnosis from a medical practitioner, in which an MRI or other imaging proves to be inconclusive. Others may not seek medical attention at all and choose manual therapy and exercise as a means of treatment. In both cases, most cases resolve in about 6 weeks, especially when appropriate therapy is provided.
Some common sources of non-specific low back pain are muscle strains to the muscles of the lumbar spine, sprains to the iliolumbar and sacroiliac ligaments, facet joint sprains, and sacroiliac joint dysfunction.
- Muscle strains: The most commonly strained lower back muscles are the Perispinals (all the little muscles attaching from vertebra to vertebra) and Quadratus Lumborums, which attach to the spine, last rib, and iliac crest. Minor strains can result in back spasms in which the musculature of the back locks down to provide stability and prevent any motion of the spine that may cause more damage to the tissue. Spasms can be very painful but it’s important to remember that that response is the body's way of protecting itself. Working on spasmed muscles too early in the injury phase can result in more pain and spasming.
- Ligament Sprains: The iliolumbar ligaments and sacroiliac ligaments attach from the lumbar spine and sacrum to the iliac crest of the pelvis and are important to providing stability to the sacroiliac joint. These tissues can be overstretched and sprained, which may result in spasming of the lower back muscles and sharp pain with specific movements, usually flexion or lateral flexion of the spine.
- Facet Joint Sprains: The facet joint is the site where the vertebra above articulates with the vertebra below near the spinous process. These little joints have a joint capsule and a set of stabilizing ligaments that can be overstretched, compressed or sprained. This may result in spasming of the lower back muscles, sharp pain with specific movements, or sensitivity of the joint when pressed on.
- SI Joint Dysfunction: The SI joint is where the sacrum meets the rest of the pelvis. This is a very strong joint that has a locking-type articulation that allows for weight bearing. There is debate on how much movement should occur at the sacroiliac joint but the consensus is that it is meant to be strong and stable. Just like any joint, it can become dysfunctional and irritated, especially with offset or unbalanced loading or stress. This can lead to inflammation and pain in the joint, which may be felt as lower back pain or pain in the buttocks.
What can we do about it?
In the case of strains and sprains, these generally will get better on their own, as long as no more damage is acquired and the time and resources are given to promote healing of the tissue. Along the way, using STM to address muscle tension that may be affecting motor patterns may be helpful. Additionally, STM can be used to desensitize painful areas and movement, allowing for a more robust response to therapeutic exercises. The quicker we can address pain, the quicker we can get people moving. When we can move, we can train and get tissue to adapt to be stronger and more resilient.
It’s worth noting that hip immobility can contribute to low back pain. When the hips are immobile and unable to access functional ranges of motion, the lumbar spine will often try to pick up the slack. For example, if the hip is unable to extend appropriately, then the lower back will overextend to make up the difference. This is important for gait patterns (walking). In normal gait, the hip should extend as we toe-off. If a person lacks adequate hip extension, every time they go to toe-off, they will extend their lower back instead. This results in excessive compression of the lumbar spine and stress to the lumbar extension muscles. This over-patterning of lumbar extension can lead to tight and shortened (facilitated) lumbar extensors, which by itself can lead to a dull ache of the lower back, but also can become problematic if the person moves into spinal flexion, given that the extensors may be lacking the ability to lengthen. Tight lower back musculature can put more stress on the passive structures (thoracolumbar fascia, joint capsules, ligaments, etc) when someone bends over to pick something up. STMs can temporarily increase the range of motion in the hips. Immediately using this new hip range of motion through mobility and therapeutic exercises consistently can create more lasting change and decrease the stress and strain that's being placed on the lumbar spine.
Not all non-specific low back pain is mechanical. Pain can be experienced in the absence of physical damage or insult to the tissue. People can also have damage to the tissue and experience no pain. A famous study conducted in 1989 looked at 67 participants with NO back pain, took MRIs of their back, and found that 21 subjects (31%) had identifiable abnormalities of the disc or spinal canals (Stenosis, disc herniation, disc degeneration, bony fragments, etc). A seven-year follow-up study of the same subjects concluded that the disruptions in the structures were a poor indicator of pain AND that the individuals who did end up with back pain were not the individuals who had the greatest degree of abnormalities (Borenstein et al., 2001). We now understand pain as being multifactorial, or rather a bio-psycho-social experience. A person's mental and emotional state can increase the frequency and intensity of pain experience.
References:
Borenstein, D. G., O'Mara, J. W., Boden, S. D., Lauerman, W. C., Jacobson, A., Platenberg, C., ... & Wiesel, S. W. (2001). The value of magnetic resonance imaging of the lumbar spine to predict low-back pain in asymptomatic subjects: a seven-year follow-up study. JBJS, 83(9), 1306-1311.