It’s Commonsense, Right? Maybe Not – When Science Tells Us What Commonsense Doesn’t

Claims for worker’s compensation benefits or personal injury damages require a health condition and a mechanism of injury that caused it.  Too often the connection between the health condition complained of and the alleged injury is weak and unscientific.  A large part of the problem is that we don’t perform large-double-blinded prospective studies on what occupational movements, activities, or exposures cause injuries and adverse health conditions.  As a result, most medical experts have little academic literature to rely on when determining whether a particular mechanism caused a particular injury or health condition.  Instead, most experts rely on their experience and training alone to evaluate causation.  In so doing, most experts make logical analyses that would be considered common sense conclusions drawn from the available facts.  This is problematic because what we intuitively believe to be correct based on logical analysis is often incorrect.

How do we know that our intuition is often wrong?  We know because the medical literature is replete with instances in which commonsense, logical assumptions were proven wrong once they were actually tested.  One example is the long-held and erroneous belief that running is bad for one’s knees.  For many years, there was near consensus among medical professionals that long distance running would cause arthritic changes in the knees because of the increased load that running placed on them.  Logically this makes sense because running does radically increase the load on the knees and many things respond to increased load by wearing faster.  A car engine that constantly revs higher than another will wear out faster.  Rapid, hard braking wears brake pads faster than gentle braking from slower speeds.  The problem is that studies found that long distance running does not cause premature arthritic changes in the knees.  How do we know this?  Studies have been done which demonstrate that the incidence of osteoarthritis of the knee is the same in long distance runners as it is in non-runners.   Commonsense logic was wrong.

The link between consuming butter and heart disease is another example of how commonsense logical analysis and intuition proved to be wrong.  We know and have known for a long time that serum cholesterol (the cholesterol in our blood) is associated with a higher incidence of heart disease.  What we assumed is that foods high in cholesterol would cause an increase in serum cholesterol.  Why did we make this assumption?  Because it is logical.  We assumed that serum cholesterol had to come from somewhere and the logical source must be our diets.  Unfortunately, this assumption was wrong.  According to the Scientific Report of the 2015 Dietary Guidelines Advisory Committee (Advisory Report), “Available evidence shows no appreciable relationship between consumption of dietary cholesterol and serum (blood) cholesterol.”  A more recent study concluded that butter had no effect on heart disease.  So what does cause high cholesterol?  According to Dr. Steven Nissen, Chair of Cardiovascular Medicine at the Cleveland Clinic, “Most circulating cholesterol is produced by the liver. Dietary cholesterol accounts for only about 15 to 20 percent of blood cholesterol. Changing the diet typically has only a modest effect on serum cholesterol levels.”  The bottom line is that commonsense logic was wrong, again.

The challenge is how to change the way medical experts evaluate medical causation.  To the extent that medical literature does exist, it would seem that developing standards consistent with sound scientific evidence is appropriate.  For example, “The Twin Study” (subscription required) analyzed degenerative lumbar disc changes among twins with different environmental exposures.  The study was multinational and multidisciplinary, taking place at research centers in Canada, Finland, and the United States.  The study concluded that,

The once commonly held view that disc degeneration is primarily a result of aging and “wear and tear” from mechanical insults and injuries was not supported by this series of studies. Instead, disc degeneration appears to be determined in great part by genetic influences. Although environmental factors also play a role, it is not primarily through routine physical loading exposures (eg, heavy vs. light physical demands) as once suspected. (Emphasis added)

In essence, the research found that occupational exposure to lifting does not cause lumbar disc degeneration.  Nevertheless, medical experts routinely attribute degenerative lumbar disc changes to wear and tear due to an occupational history of heavy lifting.  Commonsense logic suggests this should be so, the actual science does not. 

Many claims, however, fall outside areas in which there is clear scientific evidence.  In these cases, it would seem appropriate to demand medical experts issue opinions that go beyond mere conclusion.  For example, in many rotator cuff tear claims there is a significant degenerative component.  Frequently the medical experts simply state that the alleged mechanism of injury caused the tear or conversely that the tear is solely related to a preexisting degenerative condition.  These opinions are not particularly useful.  Instead, one would like to see the medical expert offer an explanation based on how the alleged injury would impact the anatomy of a shoulder with a degenerated rotator cuff.  This would ideally involve an analysis of the forces involved and how they would stress the tendon fibers that actually tear.  The rotator cuff is made up of four tendons that surround the humeral head.  Presumably specific forces to specific parts of the shoulder would be required to cause injury to the different tendons.  If the supraspinatus is torn, which is the usual suspect, then it would be helpful to have an explanation of how the alleged injury caused the tear or conversely how the alleged injury could not have caused the tear.

So how do we get such an opinion?  The simplest answer is to ask for it.  Instead of simply asking whether an alleged injury caused a condition, ask for an explanation as to why the mechanism of injury was sufficient or insufficient to cause the condition, including an explanation of the anatomical forces involved.  Not every medical expert will give the best answer, but at least if they are asked for an explanation one will typically be given.  Also, it makes sense to ask the expert to identify support for his or her conclusion in the relevant medical literature.  This way, we can inject reason into the process instead of dealing purely with assumptions and conclusions.  

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