What causes plantar fasciitis?

Causes of Plantar Fasciitis

Plantar fasciitis is primarily caused by repetitive mechanical tissue stress on the plantar fascia in the context of biomechanical abnormalities, with obesity and prolonged weight-bearing activities being major contributing factors. 1

Primary Causative Factors

Biomechanical Factors

• Foot structure abnormalities:

  • Pes planus (flat feet) 1, 2
  • Pes cavus (high arches) 2
  • Foot deformities that increase plantar pressures 1

• Muscle and tendon issues:

  • Tight Achilles tendon/gastrocnemius tightness 2, 3
  • Reduced ankle dorsiflexion 4

Activity-Related Factors

• Prolonged standing or walking 5
• Excessive running 4
• Repetitive cyclical loading of the plantar fascia 5
• Sudden increase in weight-bearing activity 4

Patient-Specific Risk Factors

• Obesity (significantly increases mechanical load on the fascia) 4, 2
• Middle age (most common demographic) 2
• Diabetes with peripheral neuropathy (loss of protective sensation) 1

Pathophysiological Mechanism

The plantar fascia experiences high mechanical tissue stress composed of:

• Plantar pressures during weight-bearing activities
• Shear forces accumulated during repetitive cycles of activity 1

This repetitive stress leads to:

1. Microtears in the fascia
2. Degenerative changes at the origin of the plantar fascia at the calcaneus 2
3. Chronic inflammation and pain

In patients with diabetes and neuropathy, the loss of protective sensation means they cannot feel the early warning signs of tissue damage, allowing continued stress on the fascia without protective behavior modification 1.

Clinical Correlation

The characteristic presentation reflects the underlying cause:

• Pain is typically worst with the first steps in the morning or after periods of rest 3
• This occurs because the fascia tightens during rest and then is suddenly stretched when weight-bearing resumes
• Pain is elicited by palpation of the medial plantar calcaneal region 4
• Discomfort increases with passive dorsiflexion of the ankle and toes, which stretches the plantar fascia 4

Prevention Strategies

Understanding the causes suggests these preventive approaches:

• Weight management for obese patients
• Appropriate footwear with adequate arch support
• Gradual increase in activity levels rather than sudden changes
• Regular stretching of the Achilles tendon and plantar fascia
• Use of orthotic devices in patients with significant foot structure abnormalities 5, 4

In patients with diabetes, regular foot examinations and proper offloading techniques are essential to prevent initial injury to the plantar fascia 1.