Pain is complicated
The biomedical model vs the biopsychosocial model
The biomedical model is based on the premise that pain is related to tissue structure. With musculoskeletal pain, this means that we are searching for a tissue abnormality as the cause of pain. Disc herniation, meniscus tear, muscle strain, ligament sprain, etc… While tissue damage can be painful, often this doesn’t explain the full picture.
If musculoskeletal pain were purely driven by tissue pathology, persistent pain should not be an issue. Advances in imaging (X-rays, CT, and MRI) would have allowed us to figure out which structures are damaged then surgery could be used to fix the problem.
However, it appears that structural abnormalities may not be sufficient to cause pain. Disc degeneration, disc bulges, disc protrusions, spondylolithesis all appear to be common in asymptomatic spines (ref). Asymptomatic rotator cuff tears are found in elite level pitchers as well as in the general public (ref). If tissue pathology and pain were perfectly correlated, there wouldn’t be so many asymptomatic structural abnormalities.
The biopyschosocial model better describes the multifactorial nature of musculoskeletal pain. This model suggests that there are three main factors that contribute to pain: (1) biological, (2) psychological, and (3) social.
Biological factors are emphasized as the reason for musculoskeletal pain. Low back pain means disc herniation, knee pain equals meniscus tear, a torn rotator cuff for shoulder pain, etc… These can definitely be the reason for pain, however, they are often overemphasized as the reason for pain (especially persistent pain).
Psychological factors can be part of musculoskeletal pain, however, they are often ignored because of the social stigma associated with them. Psychological factors will be part of musculoskeletal pain syndromes whether you choose to address them or not. Common examples include avoiding movement because pain means harm or that only a certain treatment can fix the problem (ie. surgery).
Social factors are often the least addressed factor that can contribute to pain. For example, family issues or decreased job satisfaction can lead to the development of pain. To understand how social factors can cause pain, you have to think about the purpose of pain. Pain is supposed to protect you from harm or further harm. If your social life is threatening to your wellbeing, it can trigger pain.
Pain can be a complicated experience. The biomedical model doesn’t address all of the factors that can contribute to pain. The biopsychosocial model provides a solid framework to address the complex nature of pain. Biological factors can certainly cause pain, however, psychological and social factors need to be addressed as well. A comprehensive approach to pain management will address all the factors involved in musculoskeletal pain syndromes.