Plantar fasciitis: the causes and treatment methods for foot injuries

Plantar fasciitis is a common foot injury, which can plague male or female athletes of any sport. As Alicia Filley explains, knowing how to detect and prevent this injury can keep you training and away from the physiotherapist’s clinic!

The fascia

The plantar fascia plays a key role in these functions. It is located on the plantar surface, or bottom, of the foot. It spans between the anterior portion of the calcaneus, or heel bone, and the toes. It helps to form the arch of the foot by serving as the base of the truss. The tendon of the gastrocnemius and soleus muscles, also known as the Achilles tendon, inserts into the heel bone, just behind the plantar fascia (see figure 1).



The plantar fascia is made of collagen fibres, which form a broad, dense band of tissue with little elasticity. Therefore, tension at one end is immediately transmitted to the other, acting as a ‘windlass mechanism’. When the toes are extended, the plantar fascia tightens and pulls the heel bone closer to the toes. This causes the arch to rise by shortening the base of the truss, and the joints of the foot to assume a more rigid and stable position (see figure 2). It is the combined truss and windlass mechanism that contribute to the stability of the foot during the stance phase of walking and running(2).

Movement biomechanics

The stance phase of gait begins when the foot touches the ground. In sub-maximal running, this happens at heel strike(2). As the foot progresses from the heel-strike position to a flatfoot position called midstance, its primary functions are to absorb the forces of impact and adapt to the ground’s surface.

The foot contacts the ground on the lateral heel in a supinated position, but rapidly becomes pronated as the lower leg, or tibia, progresses over the foot. This pronation allows for an increase in mobility of the intrinsic joints of the foot and the flexibility enables the foot to accommodate uneven terrain and absorb ground reaction forces. In normal pronation, with the toes straight and the arch lowered, the plantar fascia is in a neutral position.

As the tibia progresses over the foot and brings the body’s centre of gravity just forwards of the base of support, maximum pronation occurs. This marks the end of midstance and the absorptive phase(3). The propulsive component begins when the opposite swing limb moves forward and exerts an external rotation torque on the stance limb via the pelvis. As the tibia of the stance limb moves into external rotation, the midfoot begins to supinate and the heel rises off the ground. The foot remains in a supinated position throughout the remainder of the stance phase. In supination, the midfoot joints ‘lock’ into a rigid configuration, which raises the arch and provides the stability for push-off and propulsion of the limb forward.



As heel rise begins, the gastrocnemius and soleus muscles of the calf contract, causing the heel to lift and toes to point downward. This accelerates the tibia over the foot and lengthens the stance leg while the forefoot remains on the ground. The resulting extended position of the toes elongates the plantar fascia and activates the windlass mechanism.
With the plantar fascia taut, the arch raised, and the foot ‘locked’ in supination, the foot pushes off the ground and thrusts the limb forward. While the flexibility of the foot at heel-strike provides for shock absorption, it is the stability of the foot at toe-off that enables it to withstand ground reaction forces of up to 2.8 times body weight while running(3). The heel strike, midstance and toe-off phase of running gait are shown in figure 4.

Causes of fasciitis

The important role the plantar fascia plays in each step is clear. If the plantar fascia endures repetitive stress, microtears occur in the fascia at its origin on the heel bone, and result in inflammation and pain in that area. With continued pull on the insertion of the fascia, a bone spur may develop. While the bone spur itself does not cause pain, the tearing and inflammation of the fascial fibres around the spur do(4).

Anatomical, biomechanical, and environmental factors are thought to contribute to the development of plantar fasciitis(5). Anatomical variances that can strain the fascia include leg length discrepancy, flat feet, high arches, and lax ligaments. However, researchers in New Orleans, Louisiana, found that after examining 91 runners, they were unable to predict who had a history of plantar fasciitis or would develop the syndrome based on these variables(6).
Biomechanical theorists have focused on lack of control of the hindfoot as the culprit. Over-pronation during the midstance phase of gait results in increased strain on the plantar fascia. Over-pronation can occur as a result of anatomical variations, overweight, decreased strength of the intrinsic foot muscles, or decreased strength or flexibility in the calf muscles.

The impaired ability to absorb ground reaction forces due to calf muscle tightness and the inability to properly propel the limb forward due to plantarflexor weakness, result in a compensatory over-pronation that increases strain on the plantar fascia. A professional trained in the administration of the ‘Brody Navicular Drop Test’ can help distinguish anatomical from functional pronation. This test, conducted in both sitting and standing, measures the distance from the navicular bone (located in the top of the midfoot) to the ground, while keeping the hindfoot in a neutral position.

If the shoe fits…

Physical therapists in Florida reported a case where an experienced triathlete developed plantar fasciitis after competing in a half-ironman triathlon where the running course was wet(7). The 40-year-old male had used the same brand and model of running shoes for more than two years and replaced them after appropriate mileage. The athlete had also previously competed on the same course without incident and a review of his training schedule prior to the competition revealed an appropriate progression of training, but with the addition of hill work.

The athlete presented with the classic signs of plantar fasciitis. He experienced severe heel pain when first stepping out of bed in the morning

or after sitting for a prolonged period. In most cases, the pain resolves after walking or after initiation of exercise as the fascia becomes warmed and stretched. Often, there is an accompanying palpable tender mass on the heel.
Physical examination revealed mild anatomical pronation, gastrocnemius-soleus weakness, and decreased ankle range of motion of the affected leg. Examination of his training shoes revealed a mild inward lean of the outside portion of the shoes due to the repetitive pronation force exerted by the athlete while running. Examination of the racing shoes revealed a visible defect in the construction of the back of the shoe, or heel counter, which forced excessive inward rolling of the affected foot.

While the origins of plantar fasciitis appear to be multi-factorial, this athlete presented with three variables from his injury-free athletic history: the addition of hill training, a wet racecourse, and a shoe with faulty construction. The authors believed that his anatomical pronation predisposed him to developing plantar fasciitis and concluded that the faulty racing shoe was the final straw for an already stressed plantar fascia.

Treatment

Like the causes of plantar fasciitis, identifying a treatment for the syndrome is illusive. If untreated, symptoms usually resolve after a period of 6 to 18 months(8). There are many conservative treatments that are employed to manage this syndrome. Scientists at the University of Bridgeport Chiropractic College in Calgary, Alberta, conducted an exhaustive review of the literature from 1980 to March 2005 on the management of plantar fasciitis. They concluded that due to numerous methodological flaws, none of the 15 randomised controlled trials showed conclusively which conservative treatment modality was best for plantar fasciitis(9)!The rehabilitative process can be divided into acute, recovery and management phases(10):

Acute – during this phase, it’s important to control inflammation and decrease pain. Physicians recommend over-the-counter non-steroidal anti-inflammatory agents, such as Ibuprofen. Ice massage is also effective. To perform this, freeze a water bottle and roll your foot on top of the bottle over the painful area for seven to ten minutes, or until the heel becomes numb. Repeat two to three times a day, or as needed(11).

Compression is thought to be useful in this phase through taping of the foot. However, while common practice, there were no studies found to support or refute this claim. Active rest is key during the acute phase(12). Athletes need to explore cross-training alternatives that keep their fitness level up but do not stress the fascia.

Recovery – in the recovery phase of rehabilitation, the goal is to reduce stress on the plantar fascia(11). Orthotic shoe inserts are thought to provide stress relief and support the plantar fascia, but a review of several studies found them to be inconclusive and contradictory due to methodology, small study size, or lack of long-term follow-up. Based on the findings in the literature, my recommendation is to try an over-the-counter orthotic, unless you have a significant anatomical variation that would make the investment in a custom orthotic worthwhile.

For some, simply changing shoes will provide the support needed. In a telephone follow-up survey conducted by the Southwest Orthopaedic Institute in Dallas, Texas, 100 patients were interviewed on the resolution of their symptoms 24 to 132 months after treatment(13). Fourteen percent of subjects said that a change in footwear was what worked best for them.

Night splints are also used to decrease the daily strain on the plantar fascia. The characteristic heel pain on first step in the morning is due to the fascia resting in a shortened position during sleep. With the first step, the fascia is stretched and experiences re-tearing of tissues that attempted to heal over-night(10). Once again, because of methods used or small study size, it is difficult to draw conclusions from the studies reviewed. One reason may be that compliance with night splints is difficult. After review of the literature, my conclusion is that night splints can work if used consistently. Pre-fabricated models appear to be as effective as custom-made; however, finding what is most comfortable and does not disturb your sleep will improve compliance.

Management – during the management phase of treatment, the causative factors are identified and addressed. As with the other treatment modalities, studies reviewed are inconclusive. Case studies site good outcomes when treatment is based upon a biomechanical approach(14). Finding the ‘weak link’ and addressing the deficits through stretching and strengthening seems to be effective.

When plantar fasciitis seems resistant to conservative approaches, steroid injection, extracorporeal shockwave therapy or surgical intervention may be necessary. Steroid injection can also be very helpful in returning an athlete to a regular training schedule very quickly. However, the relief is temporary, and there is an increased risk of plantar fascia rupture(12).

According to a multi-centre study performed by the Fowler Kennedy Sport Medicine Clinic in Ontario, extracorporeal shockwave therapy provided significant improvement in patients with plantar fasciitis that was resistant to other conservative treatments, providing a rapid relief of pain and return to regular activity(15). Surgeons at the Palo Alto Medical Foundation, in California, who followed a small number of athletes who underwent endoscopic plantar fasciotomy, found that most returned to athletic activity within three months after surgery(16).

Prevention

The best way to prevent plantar fasciitis is to minimise your risk factors. Follow the guidelines outlined above for selecting suitable and well-constructed shoes. Progress training schedules appropriately and work in new environments slowly. Keep your calf muscles strong and flexible by making the following exercises a consistent part of your training routine:

Cross your ankle over your knee and grasp the toes at the base. Pull the toes back toward the shin until a stretch is felt in the arch and hold for one minute, repeating two to three times(17). If you feel pain on first step in the morning, perform before getting out of bed;

Stretch the Achilles tendon by leaning toward a wall in a lunge position. Perform the stretch with the toes pointed straight ahead, outward and inward. Hold each stretch for one minute and perform 2-3 times(4);

While sitting, write the alphabet in the air with your toes, three times;

While sitting, place a towel on the floor in front of you. Gather the towel with your toes. Alternatively, pick up marbles with your toes and place them in a container with your feet;

Stand on a step with your heels off the edge. Perform calf raises, three sets of ten repetitions. In between sets, let your heels relax down and hold the stretch for at least one minute.

Alicia Filley, PT, MS, PCS, lives in Houston, Texas and is vice president of Eubiotics: The Science of Healthy Living, which provides counselling for those seeking to improve their health, fitness or athletic performance through exercise and nutrition

 

References
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6. Med Sci Sports Excer 1987 Feb;19:71-73.
7. J Orthop Sports Phys Ther 2000 Jan;30(1):21-8.
8. Alt Med Rev 2005;10(2):83-93.
9. JCCA 2006;50(2):118-133.
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15(5):344-52.
11. J AM Podiatr Med Assoc 2002 Oct;92(9):499-506.
12. Sports Med 1990 Nov;10(5):338-45.
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14. J Am Podiatr Med Assoc 2002 Oct;92(9):499-506.
15. J Orthop Res 2006 Feb;24(2):115-23.
16. Foot Ankle Int 2004 Dec;25(12):882-9.
17. J Bone Joint Surg Am 2003 Jul;85-A(7):1270-7.
‘The best way to prevent plantar fasciitis is to minimise your
risk factors’