Can an ankle strain cause or exacerbate pes planus (flat foot)?

Can Ankle Strain Cause or Exacerbate Pes Planus?

Yes, an ankle sprain can potentially exacerbate pre-existing pes planus (flat foot) through altered biomechanics and weakened supporting structures, though it is unlikely to directly cause pes planus in individuals with normal arches.

Relationship Between Ankle Sprains and Pes Planus

Biomechanical Connection

• Ankle sprains, particularly lateral inversion injuries, can damage the supporting structures that help maintain foot arch integrity 1
• When ankle ligaments are injured, this can lead to:
  • Altered gait mechanics during healing
  • Weakened supporting musculature, particularly the posterior tibial tendon
  • Potential compensatory pronation during recovery

Risk Factors and Complications

• Inadequate treatment of ankle sprains can lead to chronic problems including decreased range of motion, pain, and joint instability 1
• These complications may contribute to increased stress on the medial longitudinal arch, potentially worsening existing pes planus

Diagnostic Considerations

When evaluating a patient with both ankle sprain and pes planus:

1. Determine the type of pes planus:

   • Flexible pes planus: normal arch during non-weight-bearing or tiptoeing, with flattening on standing 2
   • Rigid pes planus: arch remains collapsed regardless of weight-bearing status (requires specialist referral) 2

2. Assess ankle sprain severity:

   • Grade I: Mild stretching with microscopic tearing
   • Grade II: Partial ligament tear
   • Grade III: Complete ligament rupture 1

3. Evaluate for posterior tibial tendon dysfunction:

   • This is the most common cause of acquired pes planus in adults 2
   • Can be exacerbated by ankle injuries that affect this tendon

Management Approach

Acute Ankle Sprain Management

1. PRICE protocol (Protection, Rest, Ice, Compression, Elevation) 1, 3
2. NSAIDs for pain and inflammation control 1
3. Functional rehabilitation rather than immobilization 1
4. Semirigid or lace-up ankle supports are superior to elastic bandages 1

For Patients with Concurrent Pes Planus

1. Internal shoe modification with medial longitudinal arch support has shown the most significant clinical improvement 4
2. External shoe modification using Thomas heel as an alternative 4
3. Specific exercises to strengthen foot musculature 4

Prevention of Complications

• Complete appropriate rehabilitation before returning to full activities 3
• Use proper ankle supports, especially with history of previous sprains 1, 3
• Incorporate proprioceptive training (ankle disk exercises) to prevent future injuries 1, 3
• For patients with pes planus, maintain a healthy weight to reduce stress on the medial arch 2

Clinical Implications

Research has shown significant relationships between pes planus and increased injury rates, particularly in active populations 5. This suggests that proper management of both conditions is crucial to prevent a cycle of recurring injuries.

For patients with both ankle sprain and pes planus, addressing both conditions simultaneously is important for optimal outcomes and prevention of long-term complications affecting mobility and quality of life.