Is All Low Back Pain the Same?
No. Low back pain is quite possibly the most generalized term I hear in my practice. The lower half of the spine is wonderfully complex. Not only is the lumbar spine highly mobile, but the whole complex can vary from very stable to so unstable its scary. This stability relates directly to whether the musculature that connects to the spine is in the proper tone or not. The abdominal musculature needs a moderate amount of tone (or consistent tension) to maintain the spine to prevent it from moving far too much. Beyond the abdominal bracing features, the psoas muscle (the primary muscle that either raised the leg at the hip, or bends the torso at the waist) connects the femur to the bottom 5 vertebra. If the psoas is too tight, and the abdominals are too weak, the whole lumbar spine can be constantly pulled forward, which places a lot of pressure on the posterior joints of the spine.
What is Spinal Instability?
Imagine your spine as a game of Jenga. The top portion is your thoracic spine (mid back) with ribs attached. It’s fairly secure, and doesn’t move much. The bottom segments of blocks is your pelvis. Also very study, nice thick weight bearing bone. The middle 1×1 blocks are your lumbar spine, without proper abdominal bracing. Weak abs make for a very “flimsy” back which can easily cause low back pain. That instability may also show up in a lot of other areas. I’ll be discussing one of them below.
How Does This Affect the Facet Joints?
The posterior (further toward the back) joints of the spine are called “facet joints”. These are the joints that give the spine its mobility. There are two concave surfaces, millimeters apart, in a pool of extremely slick fluid, known as synovial fluid. They are surrounded by a tough ligamentous capsule, and present in 3 different angles. The cervical facets are in a horizontal presentation, the thoracic are in a front to back, vertical presentation, and the lumbar are in a side to side, vertical position. This allows the neck the most mobility, but also least stability. The thoracic area has the decent flexion (forward bending) but the least rotation, which is acceptable, since the rib cage prevent much movement in this direction. The lumbar facets allow for excellent forward and moderate backward movement, and rotation, but in turn limits lateral bending. The limited lumbar rotation is compensated by the high mobility by the hips.
Thoracic facet joints illustrated below.
Image retrieved from wikipedia.org 8/13/14
Each of these 3 regions complements each other to allow for high mobility, while augmenting each other’s weaknesses to remain protective. If the neck wasn’t the most mobile, the eyes and ears would have a much harder time perceiving the world around the person. The thoracic region, with attached rib cage, needs to be stable, to protect the heart and lungs, so bio-mechanically; it makes sense to limit the movement to forward, backward and rotation. This keeps the rib cage’s heart and lung space intact, while still allowing a large grasp radius for the arms and shoulders. The lumbar region is slightly more vulnerable, given that there isn’t much stability on the front, the only support the anterior portion of the lumbar region has, is the abdominal muscles; rectus abdominis, internal oblique, and external oblique. These muscles need to support and protect large and small intestines and lower section of the aorta. However, the abdominal muscles are highly mobile, strong and act as an excellent brace for the lumbar spine, when properly conditioned.
While the 3 levels of the spine compliment each other well, these compliments can occasionally be circumvented with poor movement or muscular deconditioning. The skeletal system is for rigid support to give the muscles something to pull on. The muscles guide the movement of the skeleton, but must also give the bones “soft” support so the joint capsules don’t get abused with each movement.
The end surfaces of the facet joints are covered in hyaline cartilage, which is very smooth. This allows the joints to properly slide past one another, while bathed in an “anti-slip” synovial fluid. The entire structure is bound in a tough ligamentous capsule. The synovial fluid prevents any “sticking” or friction of the joints, when the joints move properly.
When the facet joints don’t move properly, they can become “suctioned” together, given that they are two concave surfaces. This produced intense pain, when the joint tries to move, because lack of movement causes the ligaments, and surrounding muscles to inflame and swell, causing low back pain. This “suction” like effect is caused when repetitive motions are used, and when the muscles surrounding the joints are not in proper tone, thus allowing the joint to move a bit more freely than it should. When the abdominal muscles are too weak, the psoas muscle may pull the lumbar vertebra forward over stressing the lumbar facet joints. Coincidentally, in a seated position, the abdominals are classically inhibited and the psoas is overly activated. Add in the fact that most chairs are very “deep” and as a culture, we curve our lumbar spine backwards, as we sit down. This action has preemptively put you in a poor seating posture. A situation where you’re going to be sitting for an extended period of time (while at work, for instance), you shouldn’t have an overactive psoas with inhibited abdominals. This is a classic recipe for disaster and increasing low back pain. I’ve discussed this before.
This fixated state can be intensely painful, but easily remedied with proper adjustments. A skilled chiropractor can not only identify the painful joint, but also expertly manipulate that segment to restore proper motion. This procedure is quick, and normally painless. If the tissues local to the facet are inflamed, the adjustment may cause minor pain, which may last a couple of hours. Proper rehabilitation is commonly followed after the adjustment, to strengthen the muscles, to prevent recurrent injuries.
If the joint surfaces are “abused” with poor movement for extended periods of time (years), the surfaces can become damaged. This damage will cause low back pain, but many people ignore this low grade pain. As the surfaces become more and more damaged over time, the low back pain will continue to get worse, and may possibly develop into varying degrees of arthritis.