We often think that injury and pain are synonymous. We experience pain when we sprain our ankle or accidentally hit our thumb with a hammer, which makes perfect sense. But does the presence of pain actually mean that there is always an injury to the tissue? This blog post will discuss the difference between pain and injury and why it is important.
When we experience pain, we often look for the source of the pain. This frequently leads us to get imaging (X-ray, ultrasound, CT scan, MRI, etc) of the area to see what is going on. When we get the information back, we assign the the cause of pain to any structural abnormality that was found in the imaging. Disc herniation at L5? That’s the cause of your low back pain, let’s cut it out. Partial tear of the rotator cuff? We should stitch your rotator cuff back together. Meniscus tear in your knee? Time for surgery.
However, pain doesn’t seem to always play by those rules. If we take a look at the images of people without pain, those structural abnormalities on imaging are seen in a new light. Here is a quick look at some of the structural abnormalities that are often blamed for the cause of pain.
- A review of 3110 asymptomatic individuals found that disc degeneration was present in 52% of 30 year olds and 80% of 50 year olds. [Systematic literature review of imaging features of spinal degeneration in asymptomatic populations]
- The same review of 3110 asymptomatic individuals found disc bulges were present in 40% of 30 year olds and 60% of 50 year olds. [Systematic literature review of imaging features of spinal degeneration in asymptomatic populations]
- A study on 20 asymptomatic elite baseball players found that 40% had either a partial or full-thickness rotator cuff tears. Also, none of the players reported shoulder problems during the 5 year follow up. [Magnetic resonance imaging of the asymptomatic shoulder of overhead athletes]
- A study of 664 individuals found 22.1% of the general population had a rotator cuff tear. The researchers found that an asymptomatic tear was twice as common as a symptomatic tear [Prevalence of symptomatic and asymptomatic rotator cuff tears in the general population - from mass-screening in one village]
- Another study with 411 individuals found rotator cuff tears in 23% of asymptomatic shoulders [Age-related prevalence of rotator cuff tears in asymptomatic shoulders]
- Tendon pain (tendinitis, tendosis, & tendinopathy) does not equate with tissue damage [The pain of tendinopathy - physiological or pathophysiological]
- A study with 295 asymptomatic athletes found a meniscus pathology was present in 31.1% of the athletes[The prevalence of meniscal pathology in asymptomatic athletes]
As you can see, structural abnormalities (which would indicate some sort of tissue damage) are pretty common. And many of these studies were in the athletic population which means they are active and the "injury" is not a limiting factor in their performance.
So if injury and pain were synonymous than the people in the above studies should be in pain, but they aren’t. So what is the purpose of pain if it doesn’t always correlate to injury? Well pain is an output of the brain in response to a threat or a perceived threat to the body. This means that if the brain does not think something is threatening to you, there is no pain. It also means that even without an injury, you can have pain if the brain feels that you are in danger.
The problem with the biomedical model, which typically focuses on structural pathology, is that it neglects the true complexity of pain. Unfortunately, pain doesn’t always resolve by simply removing a structural abnormality. In fact, the presence of pain can also alter the sensitivity of the nervous system and alter movement patterns which may not spontaneously default back to the normal patterns once the pain is gone. Therefore, the treatment of pain needs to address all of the factors that can be contributing to the painful episode including psychological and social factors.
Pain is a very real experience regardless of whether there is an injury or not. Although structural abnormalities and tissue damage can be the source of pain, it is not always the case because pain is a complex experience. Sometimes the cause of your pain is not what you think it is.