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Dr. Cathy A. Kim, MD, APC

Plantar Fasciitis: Your Heel Pain May Originate in your Thigh

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Plantar Fasciitis: Your Heel Pain May Originate in your Thigh

Fascia in Primary Care Series

~Similar to many problems in Primary Care, Plantar Fasciitis is simple yet challenging — easy to identify, yet hard to cure.  It is another condition in the Idiopathic category: we do not understand what puts a person at risk for the condition.  About ten percent of runners will develop this condition, but most sufferers are not runners.  Most cases will resolve on their own, but up to twenty percent of patients suffer from severe pain, requiring an immobilizing boot, steroid injections, or even surgery.  

Over the years, I dutifully advised the usual — calf stretches, heel orthotics, over-the-counter analgesics, as I had been trained.  For recalcitrant cases, I even performed steroid injections, a very painful procedure that patients receive only out of desperate necessity.

As I began thinking more about our musculature as a myofascial system, I reasoned that the hamstrings (muscles at the back of the thigh that bend the knee) are capable of much more power than the calf muscle, and so perhaps, stretching the calf muscle was not enough for alleviating the tension on the plantar fascia.  I developed a technique for patients to release their own hamstrings with immediate and satisfactory results for some mild cases of plantar fasciitis.

A patient in her eighties was thrilled with the efficacy of this maneuver, as the pain no longer threatened her independence.  Months later, she reported that she was still effectively employing the hamstring technique with lasting benefit whenever the heel pain decided to flare.  I was pleased that she could relieve her own pain, but I was still wondering what was causing her heel pain to recur.  

In March 2018, the article, “Structure and Distribution of an Unrecognized Interstitium in Human Tissues,” was published by digestive and pathology researchers from New York and caught a lot of attention.  While performing “probe-based confocal laser endomicroscopy” (pCLE) to examine a liver structure during a procedure, they noticed a collagen network of tissue they had never seen before.  When samples were chemically processed for microscopic slide review in the traditional way, this structure was not visible.  Quick-freezing the samples was the only way to preserve the network for study.  They found that this complex structure is located throughout the entire body — in the skin, internal organs and the musculoskeletal system.  While pursuing their study of the gastrointestinal system, these scientists had discovered that this interstitium unifies the body’s systems and could even be called an “organ.”  

My clinical work prompted me to read even more about fascia, and I found that the number of books on the subject had quadrupled since 2010.  Reflective of this growing consciousness, the first International Fascia Research Congress had convened in 2007.  I found Fascia: What it is and Why it Matters (Lesondak 2017) to be an excellent, concise overview, and I learned that the 2018 discovery was not the first.  

Separately in France, Dr. Jean-Claude Guimberteau was also studying living tissue.  In his endoscopic work as a tendon transplant surgeon, he had noticed a collagen network that wasn’t in anatomy teachings.  In a 2010 research article, he named it the Multi Microvascular Collagenic Absorbing System (MVCAS) and this led him to identify it everywhere in the body — abdomen, chest, and around nerves and bones.  He subsequently published a book documenting his findings, Architecture of Human Living Fascia in 2015.   

A hand surgeon and gastroenterologists, in separate specialties and countries, had converged on the same concept, that a vitally important network unites our limbs and organs.  Our methods of preserving tissue and cadavers had been destroying structures that all clinicians and researchers should have been noticing for decades. 

Imaging and lab tests have standard values that are easily compared and shared with different specialists.  But fascia is not so quantifiable.   

To me, working with fascia requires accepting some degree of ambiguity — as we do with light.  Depending on the experiment, light can behave as a wave or a particle and so is said to be both.  While it is difficult to comprehend this duality, none of us writes off the existence of light.   

Our fascial network, not isolated muscles, executes the movements initiated by our brain activity.  Elements of fascia are as strong as steel while others are extremely elastic.  It distributes the force generated by our muscles and, like bone, it remodels in response to increased loads.  An individual’s movement history determines fascia’s resting tension which is revealed in the posture, whether sitting or standing.  Looking at an individual’s posture is like looking at the bottom line of an Excel spreadsheet.    

When we observe the “posture” of trees near the beach, we can infer from their “stance” from which direction the prevailing winds blow.  Our fascia stores the directional forces of habitual movements and like the coastal trees, our posture reveals the net effect of these forces.  As I began to observe the structure and movement of every individual, I noted similar patterns in postural transition that predicted the final stance.  Research is showing that gait is as individual as our signature and can even be used to predict overall health.  

When the hamstring muscles and fascia at the back of the thigh cause the knee to bend (flex), they require the quadriceps muscles and fascia at the front of the thigh to elongate and stretch.  I speculated that if the anterior thigh were stiff, it would require greater force from the hamstrings to allow stretch for knee flexion.  As a result, there would be higher resting tension in the entire leg.  This explanatory model made sense for my elderly patient’s recurring hamstring tension.  “Toilet seat risers” to accommodate poor quadriceps elasticity is a common prescription for her age group.  

We expect stiffness to accompany aging, but, assuming the same mechanism is true, why would younger patients have such inflexible quadriceps muscles?  

When examining these patients with heel pain, I found that the leg with a more symptomatic heel had the more hypermobile knee.  In general, the degree of hyperflexibility correlated with symptoms — the more severe the hyperflexibility, the younger the symptomatic age.  These individuals demonstrated movement patterns that seemed to compensate for their knee hypermobility, presumably to maintain better pelvic balance. 

With curiosity, I started releasing the fascia in the anterior thigh, which almost always resulted in immediate improvement of the heel pain.  Recalling fascia’s remodeling capability, I coupled this intervention with teaching a more functional postural transition to help avoid recurrence.  With this attention to the fascial system and biomechanics, I helped patients significantly improve their heel pain — one middle-aged patient experienced resolution of chronic bilateral Achilles tendon swelling within one week of this combined treatment and movement education.  

Of course, I personally wondered, why would we have evolved to have this problem of knee joint hypermobility?  Could so many people really just be born with this problem?  

In his book Breath: The New Science of a Lost Art (2020), James Nestor reviews the evolution of the human skull and the structural trade-offs humans made to accommodate a larger and larger brain.  One of these adaptations was for the larynx to descend, which has made humans uniquely vulnerable to death by choking.  

The downward migration of the larynx helps illustrate that evolution can be a mixed bag — advances in one dimension can be a disadvantage in another.  In exchange for our bipedal existence, it appears that we may have exposed our pelvis and trunk to the problems of unstable forces as they balance atop a pair of variably mobile knees.  Perhaps this is what our larger brains are for. ~ 

If you’re interested in additional information about plantar fasciitis, take a look at my Plantar Fasciitis category.

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Dr. Cathy Kim

Dr. Cathy Kim is a Board-Certified Family Medicine physician and Body Function Specialist. She practices in Camarillo, CA and specializes in complex cases.

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