Plantar fasciitis is a degenerative process of the plantar fascia, resulting from repeated trauma at its origin, on the heel bone. It is estimated that plantar fasciitis affects approximately 2 million people annually. Plantar fasciitis accounts for 8 to 15% of all foot pain. 76% is connected to running. It is also common in patient between the age of 40 to 60 years old.

Plantar fascia is a dense sheet of connective tissue that originates from the heel bone and fans out to attach to the five toes. It forms the inside arch of the foot. It functions as a shock absorber and a spring during walking and running. It carries as much as 14% of the total load on the foot.  

During walking, as the heel touches the ground, it turns inward (pronates)causing a slight tension on the plantar fascia because the ankle bends upward. As the body moves over the foot, as in single leg stance, the heel pronates maximally and  the plantar fascia relaxes because the ankle and the toes bend downward slightly. From here to the time the heel comes off the ground, tension in the plantar fascia increases. Hence, as the weight of the body is on the ball of the foot, the heel is off the ground, the heel turns outward (supinates) at the same time the toes bend upward, the tension on the plantar fascia reaches its maximum. At this point, the calf muscle pulls the heel bone in the back of the foot and the plantar fascia pulls the heel bone closer to the toe, resulting in compression in the bone of the foot that made the inside arch. This creates stiffness in the arch, raises the arch and provides substantial stability in the foot. Furthermore, as the plantar fascia tenses maximally, it stores elastic energy in the tendons and ligaments of the foot,  which eventually causes the compressed arch to recoil. This recoiling arch produces potential energy and kinetic energy to propel the body forward. Similar mechanics takes place in heel-to-toe runners. However, for forefoot runners, the foot stays rigid/stiff and the toes bend upward further throughout the running cycle to allow the body to propel forward faster. The key point here is the timing and the speed this mechanics is taking place. Any dysfunction in the mechanics of the foot during walking and running affects the plantar fascia and its functions.

It is believed that plantar fasciitis is associated with repetitive trauma, tight Achilles tendon or calf muscles, excessive running, faulty running shoes, running on hard surfaces, over-pronation, high-arched foot, decreased range of motion in the big toe, obesity, decreased ankle range of motion, heel spurs and excessive standing. In the elderly population, it is believed that poor intrinsic muscle strength in the foot is the cause. In patient with diabetes, plantar fasciitis occurs from peripheral neuropathy leading to intrinsic muscles atrophy, changes in the anatomic structure of the foot and joint deformities in the toes. But one thing is common among these factors. They all affect the normal functional mechanics of the foot, in some ways. Other causes of plantar fasciitis are lack of circulation and nerve impingement. There is some evidences that dead tissues and nerve impingement were found in patient undergoing plantar fascia surgery.

Classic symptoms of plantar fasciitis are pain in the inside of the heel bone and excruciating pain when taking the first step after waking up. Pain increases with prolonged standing, walking,  running and any activities that require weight bearing on the foot. 

Current treatment techniques used for the management of plantar fasciitis are resting, icing, stretching of the Achilles tendon/calf muscle and plantar fascia, night splints, strengthening of the muscles of the foot, arch supports, taping, use proper fitted shoes, and extracorporeal shock wave therapy. The success of the above-mentioned treatments are inconsistent. Some patients recover completely, some improve minimally, and others see no changes in their symptoms and are advised to live with it. Moreover, the above-mentioned treatments, address only pain, tightness and weakness. There are more to plantar fasciitis than just pain, tightness and weakness. Evidence based studies show that plantar fasciitis pain is generated by degeneration of the fascia and not from inflammatory process. The pain can only be relieved by stopping the degenerative process. Studies further show that when both, the weight on the foot and the Achilles tendon are loaded, the straining effect on the plantar fascia is two times larger. Hence, overstretching the Achilles tendon might be more damaging than previously thought. Moreover, the plantar fascia cannot be stretched because it is a dense connective tissue, but it can be released. Hence, instead of stretching the plantar fascia, release it with the use of either tool-assisted technique or manual release technique. Weakness in athlete’s feet are rare, unless there is a nerve entrapment. However, weakness in diabetic feet are common. Here, strengthening the muscle of the foot is indicated.

Hence, based on the above understanding of the mechanics of the foot during walking/running, the most effective treatment for plantar fasciitis would be to correct the abnormal mechanics of the foot and stop the degenerative process. This is accomplished by restoring the normal balance between the arch compression and the first toe bending upward. A skilled physical therapist can help you achieve that balance.

by Raj Issuree, MPT

Call STARS physical therapist, if you have any questions regarding plantar fasciitis treatment.

 

References:

Dyck D, Boyajian-O’Neill et al. Plantar Fasciitis. Clin J Sports Med 2004; 14(5): 305-309.

Buchbinder R. Plantar Fasciiitis. N Eng J Med 2004; 35

Griffin NL, Miller C et al. An investigation of the dynamic relationship between navicular drop and first metatarsophalangeal joint dorsal excursion. J Anat 2013; 222(6): 598-607

McDonald KA, Stearne SM et al. The role of arch compression and metetarsophalangeal joint dynamics in modulating plantar fascia strain in running. PLoS One 2016; 11(4): e152602

Gelber JR, Sinacore DR et al. Windlass mechanism in individuals with diabetes mellitus, peripheral neuropathy and low longitudinal arch height. 2014; 35(8): 816-824.