There are two major concepts that have muddied the waters of understanding back pain, the herniated lumbar disc and the keystone form and force concept of sacroiliac stability. These two concepts are excellent examples of two wise old sayings: “You can’t find what you want if you look in the wrong direction” and “If you believe hard enough, you can even fool yourself.”
Before 1934, the sacroiliac joint (SIJ) was considered to be the cause of back pain but it was difficult to diagnose objectively and even more difficult to treat effectively. At that time, the lumbar disc was discovered to be an additional source of back pain; diagnosis and treatment was more straightforward and more effective in some cases of extreme pain. X-rays showing a loss of disc height and narrowing of the vertebral canals led to surgical procedures that were very successful in many cases of extreme pain. With this relief, it was easy to imagine that less painful episodes were also caused by disc herniation. As a result, the sacroiliac joint was pushed to the background and forgotten by many doctors and therapists. After all, the nerves go to the entire body, so the thought was that we just follow the nerve from the area of pain to the spine and remove the disc bulge that may be pressing on the nerve. Then, the pain should be resolved; but, it didn’t always work like that. Failed back surgery has become a bane to medical science and a reason to look elsewhere for another cause of back pain.
In the mid-1900s, with the advent of biomechanics as a science, the sacroiliac joint was beginning to regain interest. Historically, anatomists were divided between whether the SIJ was stationary like a keystone, or moveable and suspended by ligaments. Then, in the late 1980s, the keystone concept of form and force closure became promoted by a small group of very influential members of the medical community, and it won the day. At the time, few biomechanical studies were being done, so their ideas were more readily accepted. As such, studies that were valid in methodology were misinterpreted to arrive at invalid conclusions. The need for another explanation for back pain, other than the lumbar disc herniation, overruled common sense, and the most incongruous ideas became accepted as fact. In addition to these mistaken beliefs, the keystone concept leaves many known principles that cannot fit into the model as dead-ends, including:
– mechanisms of injury
– the ligamento-muscular reflex
– muscular compensation patterns
– the effects of lumbo-pelvic traction on a keystone
– biotensegrity
– roughening of any joint surface, including the SIJ, is not
normal but the beginning stage of degeneration
– misleading force streams allegedly perpendicular to the SIJ
surface
– the shape of the sacral articular surfaces rounding out the
sacral edges
– SIJ movement pattern with regards to a flat joint influencing
2D rotation about a transverse axis vs. a propeller shaped
joint
influencing 3D motion about an oblique axis
– and whether nutation/counternutation – the movement of the
core structure of the musculoskeletal system, the sacroiliac
joint – has a role beyond the SIJ
Please see Keystone Form & Force Closure vs. Ligamentous Suspension for an in-depth look at some of the fallacies of the Keystone concept. After reading the information in this link, it will be evident that the keystone concept is misleading in many respects.
In order for a biomechanical model to be accepted as valid, all known and verified biomechanical functions and associations must behave as predicted by the model. Clearly, there are too many discrepancies in the keystone concept for it to be recognized as valid, while suspension has appeared to be likely in every scenario.
A New Model
The Musculoskeletal Integration Theory introduces a new model that ties all of the proven biomechanical concepts into a single consistent pattern. As such, it is the first comprehensive model that integrates the entire musculoskeletal system into a functioning whole and, by doing so, it takes the mystery out of back pain. With this knowledge, we are able to understand how to treat current injuries more effectively, as well as visualize and prevent future injuries.
Prevention involves understanding the underlying causative factors and using that knowledge to anticipate what may happen, and act to prevent it; and this is what the Musculoskeletal Integration Theory provides.
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