What is pes planus (flat foot) and how is it treated?

Pes Planus (Flat Foot): Diagnosis and Management

Pes planus (flat foot) is a common foot deformity characterized by the collapse or flattening of the medial longitudinal arch of the foot, which can be either flexible or rigid, and requires appropriate evaluation and management based on symptoms and associated risk factors.

Definition and Classification

Pes planus is defined as a reduction or absence of the medial longitudinal arch of the foot, with or without additional deformities of the foot and ankle 1. It can be categorized into two main types:

• Flexible pes planus: The arch appears normal during non-weight-bearing or tiptoeing but flattens when standing 1
• Rigid pes planus: The arch remains collapsed regardless of weight-bearing status 1

Additionally, pes planus can be:

• Congenital: Present from birth and often resolves with age as foot musculature strengthens 1
• Acquired: Develops later in life, commonly due to posterior tibial tendon dysfunction 1

Prevalence and Natural History

• Affects up to 14% of children 2
• Up to 25% of the total population has a deficient medial longitudinal arch in at least one foot 2
• In children, flexible flat feet are often part of normal development, with arches typically developing with age 2, 3

Clinical Presentation and Evaluation

Symptoms

• Many cases are asymptomatic, especially in children
• When symptomatic, patients may experience:
  • Pain in the midfoot, particularly with prolonged walking or standing
  • Fatigue in the foot or leg
  • Difficulty with certain activities or footwear
  • Associated conditions: thumb valgus, tendinitis, plantar fasciitis, metatarsal pain, knee pain, and lower back pain 4

Physical Examination

• Observe arch during weight-bearing and non-weight-bearing
• Assess flexibility by having the patient stand on tiptoes
• Evaluate for hindfoot valgus (outward turning of the heel)
• Check for associated deformities and range of motion
• Assess for signs of posterior tibial tendon dysfunction in adults

Risk Factors and Complications

• Pes planus is a recognized risk factor for foot ulcer development in patients with peripheral arterial disease or diabetes 5
• Can contribute to abnormal biomechanics and gait issues
• May increase risk of injuries with prolonged walking, especially on uneven surfaces 4

Management Approach

Non-surgical Management

1. Observation

   • Asymptomatic flexible pes planus in children typically requires only monitoring 1, 3
   • Maintenance of healthy weight should be encouraged 1

2. Orthotic Devices

   • Arch support insoles: Provide benefits by:
     • Shortening stance time
     • Improving propulsion force
     • Distributing pressure more evenly across the midfoot 4
   • Custom-made insoles: May be necessary for more severe cases or when associated with conditions like diabetes 5
   • Therapeutic footwear: Recommended for patients with pes planus who have diabetes or peripheral arterial disease to prevent complications 5

3. Physical Therapy

   • Foot and ankle strengthening exercises
   • Stretching of tight structures (Achilles tendon, gastrocnemius-soleus complex)
   • Balance and proprioception training

4. For Associated Conditions

   • Achilles tendinopathy: Eccentric strength training, stretching, and deep friction massage of the gastrocnemius-soleus complex 5
   • Anatomic misalignment: Shoe orthotics to correct overpronation 5

Surgical Management

Surgical intervention is generally reserved for:

• Rigid pes planus
• Symptomatic cases that fail conservative treatment
• Cases with significant functional limitation

Surgical options may include:

• Achilles tendon lengthening
• Osteotomies (bone-cutting procedures)
• Arthrodesis (fusion of joints)
• Arthroereisis (insertion of a silicone or metal cap into the sinus tarsi) 3

Special Populations

Children

• Most cases are physiologic (flexible, painless, and of no functional consequence) 3
• Observation is appropriate for asymptomatic children 3
• Referral to specialists is indicated for:
  • Pain
  • Rigid flatfoot
  • Progressive deformity
  • Associated neuromuscular conditions

Adults with Diabetes or Peripheral Arterial Disease

• Regular foot examinations are crucial 5
• Referral to a podiatrist is recommended 5
• Custom-made medical grade footwear may be necessary 5
• Annual comprehensive foot evaluation is recommended 5

When to Refer to a Specialist

Referral to a podiatrist, orthopedic specialist, or foot care specialist is indicated for:

• Rigid pes planus 1
• Persistent pain despite conservative measures
• Progressive deformity
• Patients with diabetes or peripheral arterial disease and foot deformities 5
• Signs of rheumatologic, neuromuscular, genetic, or collagen conditions 1

In conclusion, while pes planus is common and often asymptomatic, appropriate evaluation and management are essential, particularly in symptomatic cases or when associated with conditions that increase the risk of complications.