What Causes Low Back Pain? 

It is estimated that low back pain will affect up to 80% of Americans some time during their lives. There is no orthopedic condition that has been the subject of more scientific investigation than low back pain (LBP).  Believe it or not, despite all of this research, we struggle to answer the most basic question: want causes LBP?

Although there are many specific conditions that can lead to LBP, such as disc herniation, central stenosis, lateral stenosis, fracture, etc, it is well accepted that by far most cases of back pain are considered nonspecific in nature. This is to say that a specific tissue source of symptoms cannot be determined with any degree of certainty. Every region of the spine consists of multiple joints and structures such as bone, articular cartilage, joint capsules, ligaments, muscles and tendons – to name a few – that are all interdependent. The lumbar spine has 5 segmental levels and 15 joints, thus it is very challenging to isolate a particular structure when someone is experiencing pain.

One would think that with the wide availability of advanced diagnostic imaging, like MRI, it would be easier to identify a specific tissue source of LBP. However, imaging can be deceptive. There have been numerous research studies that demonstrate that when imaging is performed on a group of people with no back complaints, a significant percentage will have pathology evident. On the other hand, many people who are symptomatic, who even have disabling LBP, will have negative imaging findings.  This is one of the reasons why there is a concerted attempt by insurers, policy makers and some members of the medical community to curb the indiscriminant use of imaging for LBP.

This is also why it is so important that your health care provider is conducting a thorough clinical examination of your spine. Imaging findings must be correlated to clinic exam findings in order to direct appropriate treatment and avoid overtreatment (see last week’s blog).

Just because causality cannot be established with certainty, it does not mean that we do not understand factors that can contribute to LBP. We know, for example, that people in occupations requiring frequent, heavy lifting are more prone to LBP. Truck drivers are more likely to experience disc-related back pain due to the combination of prolonged sitting and exposure to vibratory forces. We also know that physiologic factors play a role. For example, it has been shown that people with chronic LBP have smaller and weaker deep spine stabilizing muscles. Psychological factors predict how people recover from episodes of LBP. There has been a surge of research on cognitive and behavioral aspects of LBP, and we are discovering that they may in fact play and even larger role in the back pain experience than physical factors. 

Next week, we will address more specifically primary and secondary prevention, and what steps you can take to improve your spine health.

Marcia Miller Spoto, PT, DC, OCS