“.as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns—the ones we don’t know we don’t know.” Donald Rumsfeld former US Secretary of Defense
In medicine, what we “know” changes regularly as long as curiosity keeps opening doors. For many decades, the complaint of pain in the bottom of the foot, just in front of the heel bone and always worse with the first few steps of the morning or after prolonged periods of inactivity, fell into the “known known” category. Doctors and physical therapists confidently made diagnoses of plantar fasciitis, certain there was inflammation in the plantar fascia, the band of tough fibrous tissue that spans the bottom of the foot. The condition was common, especially in runners, in people who spend a lot of time standing on hard surfaces and in post-menopausal women. Most of the time it resolved but there were enough prolonged and vexing cases that did not get better with anti-inflammatory medications and rest that some practitioners began to suspect that plantar fasciitis was a “known unknown” – maybe the cause was not so simple as the inflammation that they postulated. After all, no one had actually looked at the troublesome tissue under a microscope before.
Plantar fascia gets an inspection
In 2003, a Philadelphia podiatrist and pathologist, Harvey Lemont, took microscopic samples of the plantar fascia from patients undergoing surgical release of their presumably inflamed connective tissue. In all 50 samples he found no evidence of inflammation. But the tissue was not normal. The collagen structure was disorganized and degenerated, as if it had been deprived of sufficient blood flow. Some samples contained crystals from prior cortisone injections, common treatment for plantar fasciitis, but by 2000 known to carry significant risk of causing the plantar fascia to separate from the heel bone. Degeneration of plantar fascial structure, a previously unknown unknown, was discovered, and that prompted a change in the name plantar fasciitis to plantar fasciosis, a term which indicates chronic structural disruption but not inflammation.
Lack of inflammation prompts new thinking
Lack of inflammation in Dr. Lemont’s pathologic examinations explained the failure of conventional treatment many cases of plantar fasciitis. And his work raised significant questions about the cause of the problem. Why does the plantar fascia begin to degenerate? What exactly hurts? Is it the bone where the connective tissue attaches? Is it the connective tissue itself? Study of the feet of non-shoe wearing cultures in which our most common foot problems are practically non-existent, and more attention to foot, leg and gait biomechanics began to yield some different ideas, not only about the heel pain syndrome, but about bunions and hammertoes.
Are shoes the problem?
When we are babies and young children, our feet are widest at the tips of the toes. By the time we wear conventional shoes for decades, with shallow, narrow and tapered toe boxes and elevated heels (even running shoes have a 1-1.5” heel elevation), the big toe begins to curve toward its mates, which begin to curl under. The muscle that normally pulls the big toe away from the other toes is pulled inward and weakens because of inactivity. What does this have to do with the plantar fascia? The big toe muscle runs from heel to toe on the foot’s inside edge, right over the artery near the heel that supplies blood to the plantar fascia. Pulling it inward narrows the artery and decreases blood flow to the plantar fascia. It is possible that morning heel pain is ischemic pain, from lack of sufficient blood flow while the foot is dropped down during sleep. Gradual Improvement in the pain with walking may reflect better blood flow with activity, but over time insufficient blood flow takes a toll on the integrity of the tissue in the plantar fascia, adding pain from stressed attachment to the heel bone.
Wimpy foot muscles
For many years people with plantar fasciitis were told they had collapsed arches and flat feet. Or high arches and no flexibility. Or that they pronated – walking on the inside of their feet. Or supinated, walking on the outside of their feet. The treatment was external support with rigid orthotics. But feet are very individual in their structure, and there is little solid evidence that arch height causes problems. Much more evidence implicates weakness at the ends of the arch – the toes and the heels, which bear the weight of the body and are supported by muscles in the feet and in the lower legs.
A shift in treatment plans
Treatment of the heel pain syndrome is shifting to restoration of strength and flexibility in the foot. The plantar fascia functions as a windlass, a pulley that adds to the arch strength when the foot lifts at the heel and bends at the big toe joint to propel the body forward. The goal of therapy is not to stretch that windlass, but to realign the big toe and strengthen the not only the foot muscles that flex the toes and the sole, but also the muscles of the lower leg, the knee and the hip. The toes are coaxed to flatten out and spread by stretching the top of the foot and the front of the ankle and wearing toe spacers. (Useful resource below.)
In the acute phase of plantar heel pain, some external support of the foot under the arch often helps, as does a boot that keeps the foot from dropping down in bed at night. But these aids are temporary while the work of regaining foot strength and flexibility gets under way. It can be difficult to transition from elevated heels to flat shoes, and that process is almost like training for a new physical activity – short bouts at first, gradually increasing over time.
Improvement takes patience, persistence and consistency. All footwear needs to change to shoes with wide, deep toes boxes, flexible soles at the forefoot, and no elevation between heel and toe. Perhaps we will find more unknown unknowns and a way to combine healthy feet with fashionable shoes, but at the moment, the known knowns suggest that changing fashion norms to align them with natural foot function is more likely to be successful.