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The 3 Leading Proximate Causes of Lower Back Pain and Sciatica

Lower back pain and sciatica together represent the #1 reason patients come to G3 for physical therapy. We are not unique in this regard, as some report that over 80% of Americans will suffer at least one episode of lower back pain or sciatica in their lifetime, costing the US economy somewhere in the neighborhood in excess of $100 billion dollars annually, with lost wages and the cost of medical care leading the way. And the problem is only increasing, with the incidence of lower back pain and sciatica nearly doubling over the past 15 years. Clearly, this is a problem of epic proportions, and one that shows no evidence of slowing down.


Another interesting statistic is that well over 50% of initial lower back pain or sciatica incidences resolve within 6 weeks, with people seeking various forms of treatment. On the surface, this is an encouraging statistic. But, diving a little deeper reveals a more disturbing trend–up to 80% of people whose initial lower back pain resolved relatively quickly, suffer a recurrence of lower back pain within two years. Even more disturbing–these recurrences are often worse than the original occurrence, meaning, lower back pain problems are often cumulative, with recurring problems presenting with more and more severe symptoms.


So, my point that lower back pain and sciatica are huge problems is inarguable. More importantly, what are the 3 leading proximate causes of lower back pain and sciatica? Before getting into this, I wanted to briefly discuss the concept of proximate cause vs. ultimate cause. Proximate cause can be defined as the event that immediately leads to a particular problem. So, in our context, the proximate cause of lower back pain and sciatica would be that cause that is directly responsible for the lower back or sciatica pain. Again, though, a deeper dive can often reveal that beyond proximate causes, lie ultimate causes. Ultimate causes can be defined as those events or occurrences that are ultimately responsible for the problem. Indeed, in the case of lower back and sciatica pain, there are proximate causes and ultimate causes, and choosing which causes are treated, and how, will often determine the long term success of a treatment strategy for lower back pain and sciatica.


So, without further ado, the 3 leading proximate causes of lower back pain and sciatica are: 1) Herniated Disc (aka: HNP); 2) Degenerative Disc Disease, Spinal Stenosis, and Arthritis; and 3) SI (Sacro-Iliac) Joint Dysfunction. Each of the three causes have some distinct properties, while some share some common characteristics.


  1. Herniated Disc. This is typically a problem of the young, typically causing problems with people 35-40 years old and younger. First, a little anatomy of the spine. The spine is made up of segments of bone called vertebrae. The upper 7 vertebrae make up the cervical spine (aka “Neck”). The middle 12 vertebrae make up the thoracic spine. The bottom 5 vertebrae make up the lumbar spine (lower back). Below the lower back are several fused vertebral segments called the sacrum, the bottom of which is the tailbone. Separating each of these vertebral segments are discs. The discs provide cushion between the vertebral segments, and also provide space between segments that provide room so that nerves branching off the spinal cord (spinal nerve roots) can travel unimpeded. When we’re young and haven’t had the chance to beat up our bodies, our discs are like grapes–squishy discs that are full of water and pulp that act as great shock absorbers for the vertebral segments. Discs are great at absorbing compressive forces (from jumping, going down stairs, running) but not so great at absorbing “shearing” and rotational forces. Expose a disc to enough of these forces (twisting, flexing) and the “grape skin” will split, ultimately allowing the juice and pulp to squirt out, which, by itself, can cause quite a bit of pain. The real problem is when the “pulp and juice” squirts out and rests on a spinal nerve root. That can cause extreme nerve pain, often running down the leg (sciatica), and can be an excruciating problem. Patients that have lower back pain and sciatica caused by herniated discs usually have more pain with sitting or flexing, with the pain relieved by standing, lying on your stomach, or bending backwards. The pain is often worse in the morning and gets better as the day progresses.

  2. Degenerative Disc Disease (DDD)/Spinal Stenosis/Arthritis. This is typically a problem of people over 45 or so. As we age and beat up spines, our discs go from resembling grapes to resembling raisins. As such, they flatten out, and the “juice or pulp” dries out. The result of this is, the discs are not as effective as shock absorbers and they cause the vertebral segments to get closer to each other, often pinching (impinging) on the spinal nerve roots that exit the spine between the segments. People with lower back pain or sciatica caused by DDD/spinal stenosis/arthritis usually have more pain standing or walking, with the pain relieved by flexing, sitting, or lying down on their back with their feet up. Their pain is usually worse as the day progresses, and can have major pain if they sleep on their stomachs. We’ve all seen extreme cases where an elderly man or woman is at the grocery store, bent over, leaning on their shopping cart as they walk around shopping.
  3. SI Joint (SIJ) Dysfunction. SI Joint dysfunction significantly less common than the previous two causes, but are still significant causes of lower back or sciatic pain in women (particularly pre- and post-pregnancy) and anyone who has slipped and fallen on their backsides or tailbones. The SI joint is where the sacrum (bottom triangle of the spine) and the pelvis (ilium) join up. This is usually an extremely stable joint (there is a left and a right SI joint) that, for various reasons can become unstable and cause lower back pain, groin pain, and sciatic pain. The reason it is more common in women has to do with hormones and pregnancy. When women are pregnant (and possibly menstruating), they release a hormone called relaxin. Relaxin helps prepare the pelvis to expand when a woman gives birth. By it’s nature, relaxin is designed to make the pelvis unstable, thus, making the SI joint unstable. The SI joint can also become unstable when a person slips and falls on their backside or tailbone. Again, compared to the other main causes of lower back pain, SI joint dysfunction is less common, but still a significant cause of lower back and sciatic pain.


So, now that you know the three leading causes of lower back pain and sciatica, what do you do with that information? The answer to that can be tricky. On the one hand, that information is valuable, in that it gives you jumping off place where you can start doing something about your pain. The underlying cause of lower back and sciatic pain can help direct you as to where to turn for relief. All of our Doctors of Physical Therapy at G3 are lower back and sciatic pain specialists, and have all successfully treated hundreds of patients complaining of lower back or sciatic pain. If you want to make an appointment to see one of our back pain specialists, please call G3 at 760-205-1500 and make an appointment. If you have any questions or comments that I can help answer or clarify, please feel free to leave a comment below.


On the other hand, as helpful as knowing what the proximate causes of your lower back or sciatic pain is, the real gold is in knowing what the ultimate cause of your lower back or sciatic pain is. To learn about the 3 Leading Ultimate Causes of Lower Back Pain and Sciatica, stay tuned for a subsequent blog where I take a deeper dive into this common and debilitating problem.

Michael VanGilder

G3 Physical Therapy & Wellness