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AN19.1-7 | Back of Leg & Sole — Part 3

Flat Foot (Pes Planus) & Club Foot (Talipes Equinovarus)

Flat Foot (Pes Planus) — AN19.6

Definition: Loss of the medial longitudinal arch

Types:
- Flexible flat foot: Arch present on non-weight-bearing, disappears on standing. Most common type in children — usually physiological and self-correcting by age 6-8
- Rigid flat foot: Arch absent even on non-weight-bearing. Causes: tarsal coalition (congenital bony fusion), tibialis posterior tendon dysfunction (adults)

Anatomical basis: Failure of spring ligament (plantar calcaneonavicular ligament) + tibialis posterior dysfunction → medial longitudinal arch collapses → calcaneus everts (valgus), forefoot abducts, talus plantarflexes

Figure: Anatomical basis

Indian context: Commonly flagged in Army/Police/Railway medical selection. Associated with prolonged standing on hard surfaces.

Signs: Medial border of foot touches ground, 'too many toes sign' (seeing >2 toes lateral to heel from behind), loss of heel inversion on standing on tiptoe

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Club Foot (Talipes Equinovarus) — AN19.6

Definition: The most common congenital foot deformity (1-2 per 1000 births in India)

Four deformities (remember 'CAVE'):
- Cavus — raised medial arch
- Adductus — forefoot adducted
- Varus — heel inverted (varus)
- Equinus — foot plantarflexed (heel up)

Anatomical basis: Shortened intrinsic foot muscles, contracted plantar fascia, medial ligaments, and posterior capsule + tight Achilles tendon

Treatment: Ponseti method (serial casting from birth) — corrects all deformities by 6-8 weeks; last percutaneous Achilles tenotomy corrects the equinus. Success rate >90% when started in first 2 weeks of life.

Plantar Fasciitis & Metatarsalgia

Plantar Fasciitis — AN19.7

Anatomy: The plantar fascia (plantar aponeurosis) is a thick fibrous band from the medial tubercle of calcaneus to the flexor tendon sheaths of all five toes. It maintains the medial longitudinal arch via the windlass mechanism — when toes are dorsiflexed, the plantar fascia tightens, raising the arch.

Pathology: Repetitive microtrauma at the calcaneal origin → chronic inflammatory degeneration (fasciosis)

Presentation:
- Severe sharp heel pain on first steps in the morning (first 15-20 steps) → eases with activity → returns after prolonged standing
- Point tenderness at medial calcaneal tubercle
- Worsened by standing barefoot on hard floors (extremely common in Indian households)

Risk factors in Indian population: Prolonged standing (police officers, nurses, teachers, temple priests), obesity, flat foot, tight Achilles tendon, unsupportive footwear (chappals)

Figure: Risk factors in Indian population

Calcaneal spur: ~50% of plantar fasciitis cases show a bony spur on heel X-ray. Note: the spur itself is NOT the cause of pain — the fasciitis is.

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Metatarsalgia — AN19.7

Definition: Pain under the metatarsal heads (ball of the foot)

Anatomical basis: Loss of the transverse arch → metatarsal heads bear unequal pressure → fat pad atrophy or displacement → pain

Common in: Rheumatoid arthritis (causes subluxation of metatarsal heads), hallux valgus, prolonged wearing of high heels (transfers weight to metatarsal heads)

Morton's neuroma: A specific cause of metatarsalgia — perineural fibrosis of the plantar digital nerve (usually 3rd-4th web space) — feels like 'walking on a pebble'