New Treatment Modalities for the Human Foot
The human foot is explained in the context of the natural environment in which it was “designed” to operate versus the “man-made” environment in today’s industrialized society. Learn how shoes can contribute to foot issues, and how the “new modality” for protecting the feet is a simple, elegant solution.
Despite monumental strides made in the field of medicine in today's technological society, the pure fact remains that the majority of people in the civilized world suffer from some form of foot disease. This disease has a slow, insidious onset and is so well accepted by modern man that scarcely a thought is given by him to his chronic foot discomfort on a day-to-day basis.
Beyond this fact, only a fraction of our population has the knowledge or motivation to take the proper steps to remedy their chronic foot disease. The vast majority of Americans today are misinformed or confused about the type of health care professional to turn to when seeking advice or treatment for their foot disorders.
Over the past 20 years, greater strides have been made in the understanding of foot pathologies than has been accomplished since the origin of primitive medicine. Notwithstanding, little of this knowledge has had any practical direct benefit for the general population in terms of prevention of chronic foot disease.
This paper will briefly investigate the underlying cause of modern foot disease. A revolutionary new therapeutic modality will be proposed that has far-reaching and limitless potential in terms of resolving this widespread disease state.
In order to understand the current failure of the human foot in modern civilization, one only has to look at the human foot and how it evolved to support and ambulate man in the natural state. The human foot was designed and evolved into an organ that would support man in the upright position during bipedal ambulation. This organ evolved to support man on natural surfaces, i.e., grass, dirt, sand, gravel, etc.
The evolution of the human foot was never influenced by or ultimately designed for the harmonic unity with a surface covering, i.e., a shoe. The human foot has a marvelous and almost miraculous capacity to absorb shock naturally while also functioning as a rigid lever for propulsion of the human body. Indeed, to this date, no medical engineer or scientist has ever accurately reproduced a human foot in an artificial form that functions as precisely and as accurately as the human foot itself. During normal walking, the human foot turns into a spring to absorb over 1.2 times body weight at impact, and in less than .5 second turns into a rigid lever to propel the body forward. The human foot repeats this function over and over, day after day, throughout the lifetime of a human being, carrying the human the distance of at least two times the circumference of the earth in a lifetime.
The shock absorbing capacity of the bones and joints of the foot are complemented by the thick plantar skin on the bottom of the foot and a thick layer of fat cushioning known as the plantar fat pad. These two mechanisms have a more-than-adequate ability to cushion the foot and the entire body from normal impact during walking and running.
The bottom surface of the foot is richly supplied by sweat glands. In fact, the density of sweat glands on the bottom of the foot is greater than in any other part of the body. These sweat glands are unique in that they are innervated by nerve fibers from the sympathetic nervous system that normally function to prepare the human for "flight or fright." More unique is the fact that these nerve fibers release acetylcholine rather than norepinephrine, which is the normal transmitting substance of the sympathetic nervous system.
Research has shown that the sweat glands on the palms and soles, in contrast to other sweat glands in the body, respond weakly to high environmental temperatures, yet sweat freely following emotional stimulation. Therefore, under emotional stress, sweating appears at once in the palms and soles while thermal stimuli evoke only a weak response. Some researchers have postulated that sweating in the palms and soles functions to provide a pliable adhesive surface facilitating tactile activity and grip on objects. This is one mechanism closely linked to preparation for activity. In the absence of such activity, as in relaxed sleep, the palms and soles tend to be dry. Conditions of anticipation or apprehension can induce profuse palmar and plantar sweating. Thus, plantar sweating may be related to activity in higher centers of the brain. Darrow in 1937 reported that patients with a deficit in the pre-motor cortex area were unable to relax the grip on an object in the hand contralateral to the side of the lesion. This condition was also accompanied by profuse palmar sweating, indicating that the lesion resulted in a release of inhibition over muscle groups and sweating. Automatic grasping, as part of the righting reflex, appears to be linked to palmar sweating, presumably as a mechanism to improve the grip during the response. The grasping and palmar secretory response have been shown to be exaggerated in emotionally disturbed patients. No mention has been made of the relationship of plantar sweating to this grip reflex; but it is tempting to assume that it has the same function as palmar sweating.
Indeed, experimental studies have shown that friction, and therefore adhesiveness and grip, are actually facilitated by increased moisture content on the surface of the skin. This notion has carried forth in current observations of athletes who incur friction blisters while running. When the feet are wet, friction is enhanced and blistering increases. When an optimal moisture level is maintained, friction is reduced and blistering is thus reduced.
In the native state, the human foot secretes sweat from an abundance of sweat glands on the bottom of the foot during activity. This moisture facilitates the grip of the foot on the ground. The moisture evaporates at a steady state because the foot is exposed to air and the moisture is transferred to the surface touched. This natural mechanism is completely inhibited when the human foot is placed inside the closed environment of a modern-day shoe.
The forces that act upon the natural native human foot are the same forces that currently act on the modern-day human foot. These forces include: 1) vertical impact; 2) torque; 3) fore and aft shear; 4) lateral shear; and 5) pressure. In the native foot, impact forces are dissipated by the aforementioned skeletal shock absorbing mechanism and the plantar fat pad. Shearing forces, such as fore and aft shear, lateral shear and torque are dissipated by a complex dynamic mechanism involving the plantar fat pad, the plantar skin and the natural supportive surface. Inside a modern shoe this occurs at the expense of the plantar fat pads.
During normal walking and running, considerable shear forces develop between the outer skin of the foot, the supportive surface and the bones of the foot lying on top of the plantar fat pad itself. Shear develops when the metatarsal bones "glide" across the plantar fat pad that is "trapped" between the bones and the fixed plantar skin, which in turn is adhered to the supportive surface. As the bones glide forward across the natural plantar padding the "adhered" outer plantar skin and the supportive surface are moving in the opposite direction, and trauma occurs to the plantar fat pad and skin. Faulty foot biomechanics, where hypermobility of the forefoot occurs, result in unnecessary migration of the metatarsals across the plantar pads and skin. This hypermobility of the foot coupled with the normal forces of ambulation result in abnormal shearing forces of the metatarsals against the padding and skin of the foot. Breakdown of tissue results from impact, friction, and shear. Tissue response includes thickening of the plantar skin and resultant inflammation of the deeper plantar padding tissues. Inevitably, over time, repeated vertical and horizontal shearing forces on the subcutaneous tissues of the foot result in atrophy of the plantar fat pad and ultimate loss of natural cushioning.
Shearing is minimized in the natural state of the human foot walking on natural surfaces. These surfaces, i.e., grass, dirt, gravel and sand, have the ability to dissipate forces in both the vertical and horizontal planes. That is, as the human foot impacts and propels off of these natural surfaces, the surface itself gives way in both the vertical and horizontal planes. A movement interface occurs within the supportive surface itself. Movement does not occur between fixed plantar pad and skin and the metatarsal bones. The foot rests on the supportive natural surface; and the natural surface glides and gives beneath the foot, minimizing the damaging forces.
ENVIRONMENT OF THE MODERN FOOT:
Chronic modern foot disease was brought on by two major factors: 1) man-made surfaces; and 2) shoes. With the introduction of these two entities, the natural ability of the human foot to dissipate impact and shearing forces has been nearly totally obliterated. The constraints of the modern shoe in preventing the maintenance of an optimal moisture environment for the foot have resulted in the development of a host of dermatological conditions and friction-induced lesions of the feet. Finally, the fit constraints of the modern shoe have predisposed the human foot to a host of conditions and deformities that range from minor nuisances to full-scale permanent disabilities.
Modern man is forced to ambulate upon artificial surfaces that are both smooth and unyielding. Both of these characteristics severely compromise the natural function of the human foot (neither surface is found in the natural environment into which we are born).
The smooth, unyielding quality of man-made surfaces deals with the inability to deflect in both the vertical and horizontal planes. These types of artificial surfaces, in general, lack the ability to deflect frictional forces in a horizontal plane. That is, the human foot cannot dissipate horizontal oblique forces upon these man-made surfaces. This function is even more severely inhibited when the human foot is placed in a shoe, which then rests on the man-made surface. The end result is that a friction or movement interface is set up between the bones and fatty pads of the foot and the plantar skin of the foot. No movement occurs within the supportive surface, and no movement occurs within the shoe itself. Only the foot can take up the brunt of oblique shearing forces. The net result is tissue breakdown and disability.
The smooth, unyielding quality of man-made surfaces also completely negates the natural mechanism operating between the feet and the legs, which normally pumps blood from the feet and legs back to the heart. This pumping mechanism is known as the "peripheral pump." The peripheral pump relies on the natural "milking" action of the leg muscles to contract against the veins and squeeze the blood back toward the heart. These muscles are stimulated every time the human foot steps on a natural yielding surface. A natural surface is not smooth or uniform. A natural surface allows the foot to sink into it with some slight movement or rotation during the sinking movement. This stimulates leg muscle action and results in activation of the peripheral heart pump.
A smooth, unyielding surface does not allow the normal muscular contractions to occur. The foot therefore cannot mold or adapt to the man-made surfaces as it does with natural, "forgiving" surfaces. Hence, little or no muscular stimulation occurs. The result is the accumulation of fluid in the feet and lower legs. This fluid accumulation results in chronic ankle edema, varicose veins, skin necrosis, and general foot and leg fatigue.
To restate the position in other words, there are no smooth, unyielding surfaces in nature; and only an accommodative, variable yielding surface promotes correct circulation.
SHOES - A MAN-MADE, SMOOTH UNYIELDING SURFACE:
Shoes became necessary only after the implementation of artificial man-made surfaces. These surfaces provided such high friction coefficients and such diminished ability to reduce impact and shearing forces that shoes became necessary to protect the human foot. In so doing, shoes have, in general, provided some degree of protection from frictional and impact forces. However, shoes are unable to provide the dissipation of horizontal shearing forces that occur when the human foot, inside a shoe, is placed on man-made artificial surfaces. Inside the modern shoe, the plantar skin of the foot is fixed onto a firm, smooth, unyielding surface. This is an unnatural surface for the human foot to rest upon. Notwithstanding, this is the only surface on which modern man's foot now rests (that is, the surface that lines the innermost part of the modern-day shoe). This surface does not allow for dissipation of movement force in the horizontal or vertical planes.
Modern man has failed to recognize the shoe for its necessary function (that is, protection of the foot). Instead, shoes have become fashion objects. For this reason, shoes resemble ornaments or decoration and generally fail to approach the normal shape and contour of the natural human foot. The result is the prevalence of a host of pathological foot conditions resulting from an improper shoe fit.
The closed environment of the modern-day shoe completely inhibits the natural moisture environment needed by the human foot for its day-to-day function. As stated previously, a certain degree of moisture is needed on the surface of the foot to facilitate grip and normal function. The sweat glands of the foot are triggered to respond to activity intensity. They are not triggered to respond to thermal stimuli. As activity intensity increases, the sweat glands continue to pour out moisture on the sole of the foot regardless of whether the moisture is accumulating or evaporating. The natural human foot was designed to operate in an environment that facilitated the balancing of the loss of moisture (not too wet or dry; not too cold or hot; a warm, moist foot is optimal). The modern human foot cannot balance moisture loss because the foot is placed into a closed container.
The result is the accumulation of moisture and the accumulation of frictional forces beyond the optimal level. This results, in turn, in frictional lesions, including blisters, calluses, shearing tylomas, corns and ultimate ulcerations on the feet. Lesions are known to be the beginning of all foot pathologies.
PROPOSED CURRENT SOLUTIONS TO THE "PROBLEM":
Over the past 30 years, major advances have been made in the shoe industry in terms of developing cushioning materials for shoes. These cushioning materials have greatly enhanced the ability of the shoe to dissipate vertical impact forces. However, little progress has been made in developing shoes that will reduce the friction interface developing between the human foot and the shoe insole. That is, shoes continue to lack the ability to dissipate horizontal or lateral shearing forces occurring between the human foot and the shoe itself even during an activity as simple as walking.
Most forms of padding, i.e., moleskin, felt, adhesive tape and open cell insoles can only dissipate or cushion perpendicular forces. However, they fail to absorb lateral or oblique forces. In order to absorb these forces, the material placed under the human foot must have "internal, horizontal movement."
THE PROPOSED SOLUTION - A NEW DYNAMIC, NON-INVASIVE, MULTI-DIMENSIONAL TREATMENT MODALITY:
What is clearly needed to protect the modern human foot from the shoe and man-made surfaces is an accommodative gasket that is placed between the sole of the foot and the shoe itself. This gasket will also minimize vertical forces under the metatarsal heads by redistributing weight bearing across the entire sole of the forefoot. In order to absorb lateral or shearing forces, the gasket must have internal, horizontal and lateral movement.
This gasket must work in harmony between the foot and the shoe itself. Unlike insoles, which usually inhibit proper shoe fit, the gasket material must complement and enhance the fit of the shoe. Unlike insoles and padding devices, this gasket must have a long life cycle and be re-usable on a day-to-day basis. This gasket material must be directly applied against the skin of the human foot. It must take the human foot back to a more natural state (that is, this material will allow the foot to rest on a more natural surface). This natural surface is "forgiving" in both the vertical and horizontal planes, and is non-uniform.
As the foot sinks into this ''forgiving'' material, the natural muscular action of the leg is stimulated, activating the peripheral heart pump. Impact forces are minimized. Shearing forces are minimized or eliminated. Fluids are removed from the feet and leg in an efficient, natural manner. Fatigue is reduced and tissue health is enhanced.
This gasket, or protective material, will also function to remove moisture from the surface of the foot in a similar way that the natural environment normally maintains the balance of moisture. This material will effectively remove moisture in a steady state from the surface of the foot while maintaining a certain optimal level of moisture for normal foot function. Friction is thus minimized or eliminated. Skin breakdown is therefore minimized or eliminated. Plantar fat pad atrophy is minimized or eliminated.
THE NEW PROPOSED MODALITY - A DESCRIPTION:
Such a material that is so totally encompassing in its ability to return the foot to a more natural state and obliterate modern foot disease is almost impossible to imagine. Such a concept has indeed been contemplated by many scientists and health care professionals over the years. To this date, no such material, application or treatment modality has yet been conceived, designed, manufactured or implemented.
The stunning impact of this proposed new treatment modality centers around the fact that the modality itself is a variation of the most under-rated, least understood and most neglected entity of the entire foot-shoe-surface scheme: the sock. It is the sock that is most intimately opposed to the human foot inside the shoe itself. Despite all of the advances made in shoe cushioning, insoles, padding devices and orthotics, none of these modalities has the ability to directly and intimately contact the foot itself. Only the sock has this ability. Until recently, the sock has never been engineered to do anything other than cover the foot inside the shoe.
This new proposed treatment modality involves engineering "socks" in such a way that the "sock" will take the human foot back to a more natural state and therefore reduce or eliminate chronic modern foot disease. The engineering will be done in many different ways. Different construction and fiber types will be utilized to dissipate varying degrees of impact and shearing forces. Different construction and fiber types will be called upon to manage the moisture environment on the surface of the foot. Different tensile and compressive properties of the fibers and construction will be utilized to cushion and support the foot and to provide compression to aid the peripheral heart pump mechanism.
The result will be entire new lines of treatment modalities, each designed specifically to treat and/or prevent different foot conditions. Each will be designed specifically for a shoe type and the activity for which that particular shoe is worn (i.e., dress, casual, outdoor and sports). These proposed treatment modalities will eventually become the single most important foundation around which will be built the shoe and the supportive surfaces upon which we walk and run.
It is interesting to note that the advent of artificial surfaces prompted the development of shoes and research to protect the foot from these surfaces. The development of shoes was followed by the emergence of high-tech cushioned insoles and padding materials such as viscoelastic polymers and closed cell materials. But all of these have failed because none of the materials were able to exert their full effect without the cooperation of the most important material interfaced between the foot and the shoe itself; that is, the "sock." Therefore, the "sock" will be the new center of preventive or therapeutic protection and support. This new "sock" will dictate the development of whole new lines of materials to reverse the past evolution from natural to man-made surfaces, back to more "natural" surfaces (thus becoming a key component in reversing the chronic foot disease trend).
The current state of the modern human foot has been contrasted with the original natural state of the foot. Modern-day foot disease is the direct result of unnatural, smooth, unyielding man-made surfaces and poorly designed and poorly fitting shoes that compromise natural foot functions. The majority of people in modern-day civilization suffer from chronic pain and foot disease. This disease state is man-made.
A new treatment modality has been introduced that will reverse the evolution of the foot from its natural state to its current modern diseased state. This evolutionary reversal will have far-reaching impact on both the health and productivity of the entire population. Nothing less than a higher quality of life for all is the final result of this simple new concept.