Plantar fasciitis: diagnosis and therapeutic considerations

Alternative Medicine Review, June, 2005 by Mario Roxas

Abstract

Plantar fasciitis is the most common cause of inferior heel pain. The pain and discomfort associated with this condition can have a dramatic impact on physical mobility. The etiology of this condition is not clearly understood and is probably multi-factorial in nature. Weight gain, occupation-related activity, anatomical variations, poor biomechanics, overexertion, and inadequate footwear are contributing factors. Although plantar fasciitis is generally regarded as a self-limited condition, it can take months to years to resolve, presenting a challenge for clinicians. Many treatment options are available that demonstrate variable levels of efficacy. Conservative therapies include rest and avoidance of potentially aggravating activities, stretching and strengthening exercises, orthotics, arch supports, and night splinting. Other considerations include use of anti-inflammatory agents, ultrasonic shockwave therapy, and, in the most extreme cases, surgery. This article reviews plantar fasciitis, presents the most effective treatment options currently available, and proposes nutritional considerations that may be beneficial in the management of this condition.

Introduction

Description

Plantar fasciitis (PF) is a degenerative syndrome of the plantar fascia resulting from repeated trauma at its origin on the calcaneus. (1) PF is reported to be the most common cause of inferior heel pain in adults. (2) Other names for PF include painful heel syndrome, heel spur syndrome, (3) runner's heel, subcalcaneal pain, calcaneodynia, and calcaneal periostitis. (4) The word "fasciitis" assumes inflammation is an inherent component of this condition. However, recent research suggests that some presentations of PF manifest non-inflammatory, degenerative processes and should more aptly be termed "plantar fasciosis." (3,5) In the United States, more than two million individuals are treated for PF on an annual basis, accounting for 11-15 percent of professional visits related to foot pain. (6) It is estimated that 10 percent of the U.S. population will experience plantar heel pain during the course of a lifetime. (7) PF affects individuals regardless of sex, age, ethnicity, or activity level. It is seen in physically active individuals such as runners and military personnel, but is also prevalent in the general population, particularly in women ages 40-60. (2,8,9)

Etiology and Pathophysiology

The plantar fascia is a thickened fibrous sheet of connective tissue that originates from the medial tubercle on the undersurface of the calcaneus and fans out, attaching to the plantar plates of the metatarsophalangeal joints to form the medial longitudinal arch of the foot. It provides key functions during running and walking. In general, the purpose of the plantar fascia is twofold--to provide support of the longitudinal arch and to serve as a dynamic shock absorber for the foot and entire leg.

As one walks, the heel makes contact with the ground. Just after this contact, the tibia turns inward and the foot pronates, stretching the plantar fascia and flattening the arch. This allows the foot to accommodate for irregularities in the walking surface and absorb shock.

In the presence of aggravating factors, the repetitive movement of walking or running can cause micro-tears in the plantar fascia. The affected site is frequently near the origin of the plantar fascia at the medial tuberosity of the calcaneus (Figure 1). Biopsy specimens of the affected tissue reveal degenerative changes in the fascia, with or without fibroblastic proliferation and chronic inflammatory changes. (2,9)

[FIGURE 1 OMITTED]

The etiology of PF is poorly understood. While this condition can occur in association with various arthritides, the etiology is unknown in approximately 85 percent of cases. (10) In athletes, PF appears to be associated with overuse, training errors, training on unyielding surfaces, and improper or excessively worn footwear. Sudden increases in weight-bearing activity, particularly those involving running, can cause micro-trauma to the plantar fascia at a rate that exceeds the body's ability to recover. (11) When PF occurs in elderly adults, it is often attributable to poor intrinsic muscle strength and poor force attenuation, secondary to acquired pes planus (excessive pronation of the foot) and compounded by a decrease in the body's healing capacity. (11) Similarly, individuals with diabetes mellitus may suffer from PF as a result of peripheral motor neuropathy leading to muscle atrophy, changes in anatomical structure of the feet (clawtoes, pes cavus or high arches, prominent metatarsal heads, etc.), and functional alterations in gait. (12)

Risk Factors

PF is likely the result of multiple factors. Recent case-controlled studies have identified obesity or sudden weight gain, reduced ankle dorsiflexion, pes planus, and occupations that require prolonged weight-bearing as the greatest risk factors associated with PF.

One study observed that individuals with a body mass index (BMI) > 30 kg/[m.sup.2] (the cutoff for grade-II obesity) had an odds ratio of 5.6 for PF compared to those with a BMI [less than or equal to] 25 kg/[m.sup.2]. (10) The same study observed that risk of PF increases as the range of ankle dorsiflexion decreases. Individuals with < 10[degrees] of ankle dorsiflexion had an odds ratio of at least 2.1 for PF. The ratio increased dramatically as the range of dorsiflexion decreased. (10)