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Classic examples of failed “common sense” in medicine

 •  • by Paul Ingraham
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Weekly nuggets of pain science news and insight, usually 100-300 words, with the occasional longer post. The blog is the “director’s commentary” on the core content of a library of major articles and books about common painful problems and popular treatments. See the blog archives or updates for the whole site.

Common sense is dead to medicine—dead wrong embarrassingly often. Here are some classic examples:

  • Missing hormone? Replace it! Obviously helpful, right? Um, no: hormone replacement therapy for post-menopausal women was a disaster.
  • Breast self-exam for women has got to be a great idea, right? Except it may well do more harm than good. It’s certainly not a clear win.
  • Nuts and seeds, it turns, out, do not actually “lodge in diverticula and cause inflammation (diverticulitis).” So much for decades of that nutritional advice.
  • Clot in your leg? Don’t jar that loose, right? Immobilization after a deep vein thrombosis diagnosis sure seems better-safe-than-sorry. In fact, walking around with a clot in your leg is not risky at all, and probably actually helps.
  • Ulcers aren’t caused by stress, but that idea ruled for decades. Just because stress triggers or aggravates a problem doesn’t mean it’s the whole problem, or even the main one. It’s actually a bacterium that causes ulcers.
  • Severe, disabling fatigue is often caused by a terrible neurological disease, myalgic encephalomyelitis. The “common sense” belief that chronic fatigue syndrome will ease with a diligent exercise regimen is still prevalent, and “supported”… and dangerously wrong.

Tip of the iceberg, there. No doubt one could make a full book out of examples of failed common sense in medicine. Send me a note if you can think of another good example.

Major examples of failed common sense are tougher to find in more recent medical history, but there’s an avalanche of them if you go further back. For example, until the 1970s, it was “obvious” to psychiatrists that a cold mothering style caused schizophrenia. Was that a failing of their “common sense,” or just priveleged, elitist douchebaggery? It was both: common sense is based on values and culture, then and now. Go back far enough, and the common sense of the past always seems outrageous, because of the values gap. But make no mistake, it was common sense to them!

Another tip of another iceberg: failed common sense in musculoskeletal medicine

Citations for only a couple highlights here (because this is just a quick overview of topics discussed in much detail elsewhere on the site).

  • Numerous sensible-seeming surgical repairs for musculoskeletal problems have proven to be amazingly ineffective. The most obvious and notorious example is that knee debridement, “polishing” arthritic cartilage, has no effect (Moseley et al). See Knee Surgery Sure is Useless!. And a fresher example (from Ochen et al): incredibly, when people rupture their Achilles tendons, surgical repair makes little difference in recovery.
  • Immobilization and bed rest were “common sense” in rehab until surprisingly recently in medical history. Now we know that it’s critical to stimulate tissues as much as possible, as early as possible (without overloading and re-injuring, obviously). See Mobilize!
  • It seems obvious that inflammation is a natural process that aids healing and we shouldn’t interfere with it by icing. Unfortunately, this is pure speculation that is directly at odds with the hard evidence that ice has very little effect on recovery (good or bad), and that inflammation is always functional and helpful (it’s really not). See Icing for Injuries, Tendinitis, and Inflammation.
  • The common sensical notion that running on pavement is harder on runners’ joints than walking or running on softer surfaces is probably wrong (or at the very least “it’s complicated”).
  • Closely related to that: one of the most deeply held beliefs in musculoskeletal medicine is that osteoarthritis is a “wear and tear” condition — that joints break down under the onslaught of gravity and use. This fundamentally mechanical view of arthritis directly suggests that the longer we live and the heavier we are, the more likely we are to have joint trouble. But that’s just not the case: osteoarthritis prevalence doubled in the 20th Century independent of age and weight (Wallace 2017). Something else is going on. Hint: it’s neurology and immunology.
  • Surely stretching is a viable treatment for contracture (pathological tissue shortening)? Seems like an obvious job for stretching, even if you aren’t impressed by stretching in any other way! But no, it’s not actually good for this either. See Quite a Stretch.
  • When spinal discs herniate, it seems like it must be a one-way trip. But, in fact, they usually go back to normal on their own — amazing and counter-intuitive! Even more surprising? The bigger the herniation, the more quickly it may resolve.
  • And, finally, the fear of trivial physical stresses in back and neck pain especially, like “text neck” or “pack back” (see my recent post about this). Basically none of the usual risk factor suspects have panned out in musculoskeletal medicine, from classic red herrings like leg length differences to more advanced and subtle concepts like shoulder dyskinesia. Whatever’s actually going on, it’s messier and weirder than just succumbing to minor physical loads (neurology, psychology, physiology, genetics, etc).

Another tip of another iceberg.