Back pain is the most common orthopedic problem in the USA. Low back pain accounts for nearly 50% of outpatient physical therapy visits. The anatomy of the lower back is very complex with nervous tissues innervation, blood vessels, and multiple ligamentous and muscular connections. Literature has demonstrated that determining the exact physiologic source of pain is very difficult and in most cases does not help determine the correct course of treatment. It has also been illustrated that radiographic findings (MRI/x-ray/CT scan) do not correlate to an individual's symptoms. This means that someone with a significant disc herniation identified by MRI may have no symptoms or very mild symptoms versus someone with a mild disc bulge might have burning pain down their leg, nerve weakness, and reflex changes. Why is that? Why do some people have symptoms extremely worse than others when on imaging it is the other way around? The answer has to do with 4 principles and their interplay: Load, Position, Nerve Tension, and Static Posture.
Before we get into the 4 principles, I want to review current classification systems and some pitfalls. Fritz et al developed a treatment classification system in light of those findings. It is a very popular system that therapists and health care practitioners use that groups patients into 4 separate categories: Manipulation, stabilization, specific exercise (flexion, extension, lateral shift), and traction. The foremost oversight with Fritz’s classification system is the lack of acknowledgement for weight bearing sensitivity (load/compression sensitivity). If no movement caused the symptoms to improve, the author then repeated movement in quadruped but did not account for the removal of the load stimulus. Furthermore, the study goes on to state, “there continues to be a lack of evidence supporting the use of traction for patients with LBP, and the intervention is generally not recommended by systematic reviews and practice guidelines.” Load sensitivity is commonly overlooked as the primary mechanical stressor for the patient. McKenzie is another widely used protocol, but is limited in that the patients with constant severe sciatic pain with neurological deficits and patients whose symptoms stay the same or are worsened by examination procedures do not have a category.
Enough talk about other classification systems and let’s dive into the 4 principles and their interplay. I will describe load first. Load is synonymous with compression. Compression Force is the application of power, pressure, or exertion against an object that causes it to become squeezed, squashed, or compacted. As the spine gets loaded or pressure is added, the intervertebral discs and the joints will squish together. As the pressure is dispersed and the gel like substance that comprises the center of the disc moves around, pain receptors in then annular ligaments (ligaments of the disc that hold the gel like material in place) are stimulated. Load is affected by 3 general things: gravity (bodyweight, standing), external load (carrying things, lifting things), and muscle contraction (most notably the psoas and rectus abdominis). Without proper education on how everyday tasks and movements add unnecessary pressure to the lower back, these patients struggle to improve.
Moving on to position. Position is pretty straight forward, yet if it is not explained to the patient and exemplified during common daily movements, the patient will continue to hurt themselves and struggle to improve. There are 6 single plane motions or positions of the lumbar spine: flexion (bending forward), extension (bending backward), rotation left, rotation right, side bend left, and side bend right. During examination, the clinician determines what directions exacerbate the patient’s symptoms. Once determined, teaching the patient how to pelvic tilt is vitally important to their control over their own position (see my blog about the pelvic tilt here). Also extremely important is education on when those positions are encountered and how to avoid them is necessary (see my blog about education here). Sleeping is a very common task that some people end up in a position that is not good for their back, yet rarely health care practitioners discuss it. For example, if someone is side bend sensitive to the right and they sleep on their left, they might feel remarkably better with a pillow under their side (between shoulders and hips) to keep the spine from ending up in a side bent to the right position all night while they sleep.
Next is nerve tension. Nerve tension is exactly how it sounds, tension on the nervous tissue. When the nerve gets mechanically or chemically (disruption of ion flow due to inflammation etc.) irritated, it starts to become sensitive to stretch. If it is sensitive to stretch and you continually stretch it, you can guess what will happen - it will probably get worse and definitely will not get better. Nerve tension is determined by the slump test. There are a lot of components to the slump test and clinicians need to be careful of how they structure the test to avoid false negatives. There are 3 very common tasks/positions that replicate nerve tension: driving, sitting on the couch watching TV with your feet on the coffee table (being reclined is different and does not count), and stretching your hamstrings. In patients with low back pain, 99% of the time I put a hold on hamstring stretching for at least 3 weeks. Education to avoid nerve tension is very simple, and if the patient avoids it, then it will go away. However, if you don’t adjust their car seat to keep them out of nerve tension while they drive, then you are setting them up for failure.
Last, but not least is static posture. Static posture is a sensitivity caused by pressure on structures over an extended period of time. Unfortunately, today’s working world is turning more and more static and this sensitivity is becoming more and more common. Static posture sensitivity is harder to determine than the others, because it mostly relies on an accurate history of common daily tasks and pain patterns throughout the day (when it is the worst/best, how it trends from morning to night, etc.). Patients that exhibit lumbar hypermobility and signs/symptoms of instability often are sensitive to static posture. Education to keep moving, adjust position slightly throughout the day are key to help decrease these patient’s pain.
Most patients’ symptoms are affected by a combination of the mechanical stressors and in some patients all of the stressors are contributing. Here’s a quick example of what I mean: flexion in standing is painful, but flexion in quadruped is not painful. This suggests the patient in load sensitive only when in a certain position - that position being flexion. Take a look at the Venn diagram and you’ll notice there are multiple combinations of mechanical stressors (not only the example I stated above). The different mechanical stressors interact so that patients with the same pathological diagnosis have a very different directive for treatment, especially regarding the education of the patient (see my blog about education here). Thus, why education of each mechanical stressor (load, position, nerve tension, static posture) is important and getting the patient to understand and problems solve the interplay of all of them is so pivotal. I encourage you to reflect on some of your patients with this mindset and see if adjusting some of their daily tasks. If you have questions, please comment below and I will promptly reply!
References
Fritz, J. M., & Cleland, Joshua A, Childs, John D. (2007). Subgrouping patients with low back pain: Evolution of a classification approach to physical therapy. Journal of Orthopedic and Sports Physical Therapy, 37(6), 290-302.
Langaas, M., Antonelli, W., Buscemi, V., & Visnick, A. (2010). Review of classification systems of patients with low back disorders. Unpublished manuscript