Flat Foot (Pes Planus): Flexible vs Rigid, Jack's Test & Insoles

Flat Foot (Pes Planus)

Pes Planus is the loss of the Medial Longitudinal Arch. It is normal in toddlers (due to fat pads) but may be pathological if rigid or painful in older children/adults.

1. Classification

• Flexible Flatfoot (Most Common): Arch disappears on standing but reappears on tiptoeing or sitting. Usually asymptomatic and physiological.
• Rigid Flatfoot: Arch is absent in all positions. Associated with underlying pathology (Tarsal Coalition, Vertical Talus, Arthritis).

2. Clinical Assessment

Diagnostic Tests:
1. Jack's Toe Raise Test: Extending the big toe restores the arch (Windlass Mechanism) = Flexible.
2. Heel Rise Test: Heel turns into varus (inversion) when standing on tiptoes = Flexible. If it stays valgus = Rigid/Tibialis Posterior dysfunction.
3. Too Many Toes Sign: Viewed from behind, more toes are visible laterally (indicates forefoot abduction/heel valgus).

3. Management

• Asymptomatic Flexible: No treatment needed. Reassurance.
• Symptomatic: Arch support insoles (Medial arch support + Heel cup), Stretching Achilles tendon.
• Rigid/Painful: Surgery (Calcaneal osteotomy, Arthroereisis, or Fusion for coalition).

25 Practice MCQs

Q1. The Medial Longitudinal Arch is primarily supported by:

Answer: A). Spring ligament supports the Talar head.

Q2. Jack's Test involves:

Answer: A). Activates the Windlass mechanism (Plantar fascia tightens, arch rises).

Q3. Congenital Vertical Talus causes:

Answer: A). Talus is vertical; requires surgery.

Q4. Tibialis Posterior Dysfunction leads to:

Answer: A). Loss of dynamic arch support.

Q5. Tarsal Coalition is:

Answer: A). Causes Peroneal Spastic Flatfoot (Rigid).

Q6. In flexible flatfoot, the heel is in:

Answer: A). Calcaneus tilts outward.

Q7. "Too Many Toes" sign indicates:

Answer: A). Viewed from behind.

Q8. Most common tarsal coalition is:

Answer: A). "Bar" between bones.

Q9. Are insoles necessary for asymptomatic flexible flatfoot in kids?

Answer: B). Can be uncomfortable and useless.

Q10. The keystone of the medial longitudinal arch is:

Answer: A). Supported by the Spring Ligament.

Q11. Treatment for Tibialis Posterior Dysfunction (Stage II - Flexible) is:

Answer: A). Restores function and alignment.

Q12. Single Heel Rise Test failure indicates:

Answer: A). Cannot invert the heel to lock the midfoot.

Q13. Accessory Navicular (Os Tibiale Externum) can cause:

Answer: A). Extra bone medial to navicular.

Q14. Flat foot is normal in children until age:

Answer: A). Arch develops as fat pad disappears.

Q15. Triple Arthrodesis fuses which joints?

Answer: A). Salvage for rigid/painful deformity.

Q16. What is the Windlass Mechanism?

Answer: A). Makes foot rigid for push-off.

Q17. Medial column of the foot includes:

Answer: A). Dynamic side.

Q18. Lateral column lengthening (Evans Osteotomy) helps:

Answer: A). Pushes the forefoot back into adduction.

Q19. Silfverskiold test differentiates:

Answer: A). Tight Achilles exacerbates flat foot.

Q20. Arthroereisis involves:

Answer: A). "Internal orthosis".

Q21. Ehlers-Danlos Syndrome causes flat foot due to:

Answer: A). Arch collapses under weight.

Q22. The Spring Ligament connects:

Answer: A). Calcaneonavicular ligament.

Q23. Custom orthotics for flat foot usually have:

Answer: A). Corrects valgus and supports arch.

Q24. Rocker Bottom Foot in children is due to:

Answer: A). Convex sole.

Q25. Charcot Foot results in:

Answer: A). Diabetes complication.