published 6/27/07
Debunking the Biomechanical Bogeyman
Better late than never, medical opinion is turning against a common but “intellectually constrained” explanation for chronic pain
by Paul Ingraham, Vancouver, Canada MOREclose
Credentials and qualifications
I am a writer and retired Registered Massage Therapist (unusually well-trained for a massage therapist, a 3000-hour program). I’m almost done with a Bachelor of Health Sciences degree. I am a peer reviewer for The Natural Standard, and a copyeditor for Science-Based Medicine. My most important qualification is more than a decade of workaholic post-graduate study, clinical experience, and constant conversations with readers from around the world, including many experts who have provided countless suggestions and criticisms.
For more information, see: Who Am I to Say? More information about my qualifications, credentials and professional experiences for my readers and customers.
Credentials and qualifications
I am a writer and retired Registered Massage Therapist (unusually well-trained for a massage therapist, a 3000-hour program). I’m almost done with a Bachelor of Health Sciences degree. I am a peer reviewer for The Natural Standard, and a copyeditor for Science-Based Medicine. My most important qualification is more than a decade of workaholic post-graduate study, clinical experience, and constant conversations with readers from around the world, including many experts who have provided countless suggestions and criticisms.
For more information, see: Who Am I to Say? More information about my qualifications, credentials and professional experiences for my readers and customers.
For decades now, there has been an unfortunate tendency in the world of musculoskeletal health care to explain injuries only in terms of structural problems — biomechanical bogeymen like leg length differences or flat feet. This simplistic perspective has simply failed to produce accurate predictions or therapeutic results for patients.
Time after time, scientific research has shown only that most biomechanical problems correlate poorly with virtually every kind of chronic pain. Many people who have such problems just do not have any symptoms. And many people with symptoms nevertheless have good posture, perfectly aligned pelvises, ideal knee angles, and so on.
“Structuralism” is slowly giving way to a more satisfying way of explaining stubborn pain — a physiological explanation, instead of a mechanical one — and more and more doctors and researchers are getting on board.
Biomechanical problems correlate poorly with virtually every kind of chronic pain.
In 2005, Dr. Scott F. Dye, an orthopaedic surgeon in San Francisco, published another explanation for patellofemoral pain syndrome (PFPS), a common knee problem. His explanation is entirely biological, not structural, and he makes an issue about the difference: “The fundamental issue at the core of the patellofemoral pain problem, in this author’s view, has been the limited conceptualization of the genesis of anterior knee pain to that of a pure structural and biomechanical perspective.” His opinion was published in Clinical Orthopaedics & Related Research in an article called, “The pathophysiology of patellofemoral pain: a tissue homeostasis perspective”
Overuse injuries in particular make much more sense when you start to think of them as a problem of tissue irritation, rather than as the consequence of being crooked or mechanically deranged in same way. Bones, ligaments, tendons, muscles and joint capsules can get quite unhappy without exactly being inflamed. All of these structures are fantastically complex, biochemically speaking. It’s a laboratory in there. When pushed to the limits of endurance, they go into metabolic overdrive, juggling molecules like crazy as they strive to adapt. The closer you get to the limits of the system to cope, the more the nervous system begins to interpret all of this adaptive chemistry as a warning of impending tissue failure. Only when tissue actually fails do you get the painful chemistry of full inflammation. But there is plenty of painful chemistry before that point.
Bones, ligaments, tendons, muscles and joint capsules can get quite unhappy without exactly being inflamed.
Most overuse injuries occur in anatomical situations where it is difficult to let tissue rest and recover from all this metabolic hyperactivity. Plantar fasciitis is perhaps the easiest example to understand: once irritated, the tissue on the bottom of your foot is obviously vulnerable to further irritation. Like a rock in your shoe, once the irritation sets in, every step becomes a problem.
Another good example is the knee. Once the knee is irritated, it is hard to calm down. The joint between your kneecap and your femur is incredibly tough. It has be — its job is to allow for awesome leverage on the shin when the quadriceps contract. Pressures in the joint skyrocket to many multiples of body weight when you jump up and down. Even when “resting” the joint in a flexed position, it’s like a vice under there. But the price we pay for this is that, if we push the joint too hard one day, it is extremely difficult to rest it after that … and then even mild activities continue to piss it off.
Like a rock in your shoe, once the irritation sets in, every step becomes a problem.
Thus patellofemoral pain syndrome is one of the most common, and infamously stubborn, overuse injuries in the world. Runners in particular get it, and often struggle for months or years to get it under control, if they ever do.
The same kind of logic applies to virtually all overuse injuries, and is much better at explaining them than structural theories. Dr. Dye also believes that it makes for much more effective treatment and self-treatment of overuse injuries in the knee. He writes, “Fundamental to rational, safe, and effective treatment for any orthopaedic condition is an accurate understanding of the etiology of the symptoms.” But with an exclusively structural view of knee pain, therapists are prompted to waste your time trying to “correct” irrelevant biomechanical problems, and surgeons are led to try to “repair” imaginary deficiencies. Dr. Dye writes:
The worst cases of patellofemoral pain, in my experience, are in those patients who have been subjected to such well-meaning but … aggressive surgical procedures for symptoms that were initially only mild or intermittent in nature.
Dr. Dye believes that we must therefore move decisively into a new way of thinking about overuse injuries. Metabolic distress in bone, for instance, can be imaged with modern bone scanning techniques, but not with the more conventional x-rays and MRIs, which are always used to detect barely relevant structural problems:
Such an intellectually constrained view [as structuralism] does not include the complex pathophysiologic factors that may be of etiologic significance in living, symptomatic joints. With the traditional structural view of patellofemoral pain, it is as if an astronomer were trying to understand the complexity of the cosmos solely with data obtained from optical telescopes that collect only visible wavelength photons.
And what does this mean for you, the patient with an overuse injury? It means that The Art of Rest is the most important treatment option you have! Ask yourself: am I really resting this part of my body? Or am I still somehow irritating it every day? Perhaps the best thing about this new medical view of chronic pain is that it is generally empowering to the patient, implying a simple and inexpensive self-treatment method. Better late than never!
For more information about the tendency of therapists to exaggerate the importance of structural factors, see Your Back Is Not “Out” and Your Leg Length is Fine.
