A Case for Both Internal and External Support in the Painful Foot

Dr. Melanie Carlone, RYT

Doctor of Physical Therapy
Founder, Custom Orthotics Solutions, Inc.
Springfield, OR

When the ambulatory patient becomes immobile, life as it was previously known changes dramatically. If a client cannot adequately and with least pain, support themselves on their feet, they cannot hope to move and exercise their lower extremities and bodies in a meaningful way. Moshe Feldenkrais, an Isreali physicist and human movement visionary, succinctly said “Movement is Life”. Truly, at it’s core, the way we move is essential to our optimal function, maximal resilience and immunity, reduced tissue stagnation forces and improved healing times in cases of active injury or chronic wounds. Effective treatment for this patient population can be sadly lacking. Patients travel from one practitioner to another in search of relief and return of function. Comprehensive treatment is rare and piecemeal, serial approaches rarely work. Everyone becomes discouraged. A unified collaborative plan is essential. Practitioners who assess and address gait abnormalities, wound-off loading issues, core strengthening for foot and trunk, and custom supportive orthotic devices make significant positive contributions, both for the therapeutic team and in the life of clients. This is particularly notable for the complex patient such as the chronic wound, diabetic and lymphedema patient population. Best-practice outcomes greatly increase patient motivation, feedback loops and participation by proactively addressing sore and painful ambulation issues.

The human body is a truly amazing structure and reflects our evolutionary journey allowing for critical endurance walking and running for survival.1 Human foot anatomy specifically reflects an ability to support the body during running, separating us from our ape ancestors as it contains “leg springs”, a dome-like structural element, which include the Achilles tendon, the tough plantar aponeurosis and the spring ligaments on the bottom of the foot.2 Because of this unique adaptation, the foot has enormous capacity to mold itself to uneven surfaces by being flexible in the first half of stance but becoming a rigid lever system during the latter half of the gait cycle. This useful function is an effect of important foot mechanisms such as an enlarged and permanently adducted hallux, shortened lateral toes, compaction and realignment of the tarsal bones. Our ape ancestors do not tolerate prolonged walking due to “mid-tarsal break” which causes stressors which humans avoid with differently adapted feet.3 Our well-defined medial longitudinal arch is supported by strong plantar structural elements. It is these elements we shall look at more deeply in this article.

When the foot becomes painful, our overall function is greatly affected. We must consider possible causes and treatment of the dysfunction to determine how the “core” of the foot dome-like structure had been altered.

  • What are the overall dynamic elements of dysfunctional gait?
  • Are there wounds or underlying stasis issues that need to be addressed and offloaded?
  • Weak intrinsic or extrinsic foot muscles?
  • Neural “laziness” reducing effective foot control due to such factors as radiculopathy, neuropathy or overprotecting shoe wear?
  • Structural ligamentous alterations reducing effective alignment?
  • Arthritic changes due to chronic unaddressed dysfunction?

Assessing and addressing relevant factors establishes an effective comprehensive treatment approach. Unsupported or poorly supported joints of the foot quickly lead to “itis” (inflammation) in our “arth” (joint) = “arthritis”. The structural realignment afforded by proper orthotics and a proper maintenance program can make all the difference. Using appropriate orthotics (either as a rehab element or for maintenance), gait retraining and strengthening programs can eventually reduce or even resolve foot pain issues. In cases such as chronic overuse injury or injuries involving disruption of supportive tendons and ligaments, or neuropathy in which sensory receptors are permanently altered, resolution may not be possible but increased function is possible with ongoing patient participation in strengthening and using orthotic support to minimize arthrokinematic tension, pain and dysfunction.

Let’s take a closer look at the concept of the structural dome-like “foot core”. The concept of “core strength” to allow for optimal healthy movement of the limbs on a stable spine has been increasingly and understandably popularized by “core stabilization rehabilitation” for spine and low back health. This has had a positive impact on difficult to treat and debilitating back pain issues. A strong “core” equates to effective structural support for the way our anatomy was designed to work. Just as the spine has it’s optimal alignment and strength for pain-free function, so too does the foot have a “core system” providing proper alignment and optimal functional use. Injury of the spine can cause deteriorated function that requires re-training. If the stabilizing segmental muscles of the spine are inhibited following pain or trauma, their recovery is not automatic and specific motor control retraining may be necessary for functional recovery of these muscles.4 So too the core of the foot can be degraded by injury to any of it’s functional subsystems and retraining these systems is necessary for recovery of function.5

Figure 1 Illustration by Tom Dolan, MS, medical illustrator and multimedia developer, Department of Academic Technology at the University of Kentucky.

For simplicity we can divide any “core system” into passive and active components. It is helpful to look at each system and how they are relevant to comprehensive intervention in both a rehab and maintenance therapeutic approach. The passive subsystem consists of the bony, ligamentous and articular structures that make up an anatomical functional unit. The active subsystem consists of the muscles and tendons attaching to and acting on the anatomy being considered, in this case, the foot. The neural subsystem consists of sensory receptors in the skin, joint capsules of the lower extremity bones, their ligaments, muscles and tendons both in the foot muscles (intrinsics) and the lower leg (extrinsics). These vital sensory feedback loops provide key information to the constantly adapting circumstances of the human in pedal motion. In a closer look at the passive subsystem of the foot core, we encounter the bones, ligaments and joint capsules that maintain the various arches of the foot. There are four distinct arches in the foot which include the medial and lateral longitudinal arches as well as the anterior and posterior transverse metatarsal arches.6

Often viewed as separate structures, there is increasing understanding that these arches interact coherently. McKenzie proposes that these arches coalesce into a functional “half dome” allowing for flexible adaptation to load changes during dynamic activities.7 This half dome has been thought to be predominantly supported by passive structures including the plantar aponeurosis and plantar ligaments.8 The good news for painful foot sufferers is that offloading with orthotics can bring instantaneous relief and then the dynamic support of the arches can be enhanced through both intrinsic and extrinsic foot muscle rehabilitation and various other approaches such a proprioceptive taping.9 This passive and active subsystem retraining can then help reset the plastic neural mechanism for better performance of the structure of the foot during weight bearing activity.

The neural subsystem consists of the sensory receptors in the skin, plantar fascia, ligaments, joint capsules, muscles and tendons involved in both the active and passive subsystems. It is well accepted that plantar sensation is a critical element to gait and balance. Contributions of the plantar cutaneous receptors to this intricate interplay has been most extensively studied.10-14 In the painful foot patient with pathological challenges such as diabetes or chronic venous stasis or lymphedema and their associated active, passive and neural changes, orthotic support in addition to patient participation in a maintenance program becomes a critical and necessary intervention for effective wholistic treatment. The degree of orthotics weaning tolerated in a comprehensive treatment approach depends on the return of health and function to each of the affected subsystems with a tailored rehabilitation program. When irreversible anatomical changes have occurred, maintenance may be the optimal outcome and complete resolution of functional loss or pain is not always possible.

Surprisingly, education and treatment for intrinsic weakness of the arches in the foot is not terribly complicated but difficult to find. The intrinsic foot muscle test can both test and re-test for progress and provide a functional strengthening program for the compromised patient. This test evaluates the patients ability to maintain a neutral foot posture and medial longitudinal arch height during single limb stance. To perform this test, the clinician sets the patient’s test foot in subtalar neutral with the calcaneus and all the metatarsal heads on the ground, and asks the patient to fully extend the toes. The patient then lowers their toes to the ground and is asked to maintain the foot position in single limb stance for 30 s without gripping the toes (an indication of extrinsic muscle overactivity and intrinsic weakness).15

Traditionally, therapeutic exercise of the plantar intrinsic foot muscles has been activity such as toe flexion exercises like towel curls and marble pick-ups. While these exercises certainly do activate some of the plantar intrinsic muscles, they also involve substantial activation of the extrinsics, like flexor hallucis longus and flexor digitorum longus muscles. These muscles are far less effective in controlling the arch and more prone to overuse injury. Recently, the ‘short foot exercise’ has been described as a means to isolate contraction of the plantar intrinsic muscles. 16-18

Figure 2 The foot is ‘shortened’ or “domed by using the intrinsic muscles to pull the medial, transverse and lateral arch arches of the foot into a dome or parachute type structure.

The three points that form the plantar arch are the center of the heel, the first toe ball and the little toe ball. The patient is trained to “shorten” the length of the foot, avoiding rolling the femur and adversely affecting pelvic alignment. It may require initial training in sitting to achieve both lifting and pelvic neutral position. Internal awareness is required for patients who have lost this sensory and muscular control. Using a mirror is preferred to looking downwards. The goal is for the patient to sense subtalar neutral with a neutral pelvis and the calcaneus and the metatarsal heads on the ground, shoulder girdle relaxed. The toes are neither flexed nor extended (the positioning described earlier with the intrinsic foot muscle test). The patient then exercises by shortening the foot by using the plantar intrinsic muscles.

The short foot exercise can be performed in progression from sitting to bipedal, to unipedal positions, followed by functional activities such as squats and single leg hops. Promising studies show that minimal arch support or barefoot walking and running can result in an increase in foot “doming” and improved sensory inputs for healthy foot function. However in the pathological foot with either arthritic changes or neurogenic dysfunction, orthotic intervention is not only useful to decrease pain and increase function but may well be the only way to achieve a desirable outcome.19

It is hoped this paper will stimulate discussion and consideration for our complex painful foot population. It is the authors intention to found an orthotic fabrication company, Custom Orthotic Solutions, in Eugene/Springfield, OR. that will provide a service to collaborate with local orthopedists, MD’s, PT’s and relevant health providers. We will employ evidence-based practices for the painful foot population, whatever the cause, and encourage positive outcomes based on increased patient motivation and practitioner satisfaction, proactively addressing debilitating painful ambulation issues.

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