Definition

The plantar fascia is a multilayered fibrous aponeurosis that originates from the medial calcaneal tuberosity and extends distally, becoming wider and thinner and splitting into five bands. Each band then divides into a superficial and deep layer to insert onto the transverse tarsal ligament, flexor sheath, volar plate, and periosteum of the base of the proximal phalanges of the toes [1] (Fig. 92.1). Plantar fasciitis is an overuse injury resulting from repetitive microtears of the plantar fascia at its origin at the tuberosity of the os calcis deep to the distal medial heel pad [2]. It is classically described as a local inflammatory reaction, although recent research has demonstrated the relative absence of inflammatory cells in the injured tissue, suggesting more of a degenerative process; therefore, the terms tendinosis and fasciosis are advocated [3].

Plantar fasciitis is one of the most common injuries of runners. This condition occurs equally in both sexes in young people; some studies show that a peak incidence may occur in women 40 to 60 years of age [4]. The condition is typically precipitated by a change in the athlete’s training program. Such changes may include an increase in intensity or frequency, a decrease in recovery time, or a change in terrain or running surface. In the nonathlete, an increase in the amount of walking, standing, or stair climbing may also precipitate symptoms. There is a correlation of plantar fasciitis with professions requiring prolonged standing (e.g., police officers and hairdressers).

Risk factors such as pes planus (flat feet), pes cavus with rigid high arches, excessive pronation, obesity, Achilles tendon contracture, and poor footwear (usually a loose heel counter and inadequate arch support) may contribute to the development of this condition. Multiple authors have demonstrated that the successful treatment of plantar fasciitis is not contingent on the surgical removal of a heel spur (calcaneal enthesophyte). Studies have shown that only 50% of patients with plantar heel pain had a heel spur and that only 10% of patients with a heel spur were symptomatic [5].

Symptoms

Patients typically complain of sharp, knife-like pain in the plantar aspect of the heel at the base of the fascial insertion to the calcaneus. Pain is generally worse with standing or during the initial steps on awakening or after prolonged sitting. Patients will often complain of the classic “pain with the first steps in the morning” that eases after being up and about for a while. Pain also typically worsens at the beginning of an exercise session but decreases during exercise. The athlete may describe being able to “run through” the pain. Complaints of numbness, paresthesias, or weakness are atypical for plantar fasciitis; therefore, if these complaints are present, the clinician should suspect an underlying nerve injury.

Physical Examination

Palpation reveals tenderness at the origin of the fascia of the medial calcaneal tubercle, but there may be tenderness along the majority of the fascia. Range of motion often reveals limited great toe dorsiflexion from a tight plantar fascia as well as decreased ankle dorsiflexion from a tight Achilles tendon. Dorsiflexion should be tested with the knee straight (gastrocnemius on stretch) and with the knee bent (gastrocnemius relaxed, soleus on stretch) to better differentiate tightness of the gastrocnemius and soleus muscles. The neurologic examination should reveal normal muscle strength, sensation, and deep tendon reflexes, unless a concomitant neuropathy is present.

Functional Limitations

Depending on the severity of disease, patients may complain of symptoms only when they try to increase running intensity or distance. More severe cases may significantly limit a patient’s ability to ambulate during daily activities or climbing stairs. Professions requiring extensive walking or standing (e.g., postal workers, nurses, or waitresses) may require job modification as well as more aggressive splinting or even casting during the initial phase of treatment.

Diagnostic Testing

Plantar fasciitis is usually a clinical diagnosis. However, radiographs of the foot may be helpful in ruling out other potential causes of heel or foot pain. It is a common misconception that the pain of plantar fasciitis is the direct result of the often (50%) associated anterior calcaneal enthesophyte (heel spur). In fact, a study of 461 asymptomatic patients showed radiographic evidence of heel spurs in 27% of those studied [5].

Electrodiagnostic testing (electromyography) may be helpful in ruling out the possibility of a nerve entrapment.

Ultrasound and magnetic resonance imaging studies may be helpful before surgical intervention is considered; these studies may demonstrate signal changes or swelling within the fascia. Magnetic resonance imaging usually demonstrates edematous involvement of the calcaneal insertion of the plantar aponeurosis, with marked thickening of the central cord of the plantar fascia.