Flatfoot Deformities

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Introduction & Anatomy - Fallen Arches 101

Pes planus, or "fallen arches," signifies the collapse or flattening of the medial longitudinal arch (MLA) of the foot. This common deformity can be flexible or rigid.

  • Core Anatomical Components:
    • Medial Longitudinal Arch (MLA): Keystone arch; primary shock absorber.
    • Tibialis Posterior Tendon (TPT): Crucial dynamic stabilizer; its dysfunction is a common cause.
    • Spring Ligament (Plantar Calcaneonavicular): Major static supporter of the talar head.
    • Deltoid Ligament Complex: Provides medial ankle stability; can attenuate in progressive deformity. Foot arches and supporting structures

⭐ The tibialis posterior tendon is the primary dynamic stabilizer of the medial longitudinal arch; its insufficiency is a hallmark of adult-acquired flatfoot.

Etiology & Classification - Why Feet Flatten

  • Etiological Types:

    • Congenital:
      • Tarsal Coalition: Bony fusion (calcaneonavicular, talocalcaneal). "Painful peroneal spastic flatfoot".
      • Congenital Vertical Talus.
    • Acquired: Develops later.

      ⭐ Posterior Tibial Tendon Dysfunction (PTTD) is the most common cause of adult acquired flatfoot.

      • Charcot Arthropathy: Neuropathic joint destruction (common in diabetes).
      • Ligamentous laxity (e.g., Ehlers-Danlos).
      • Trauma, Inflammatory arthritis (e.g., RA).
  • Classification by Flexibility:

    FeatureFlexible FlatfootRigid Flatfoot
    ArchCollapses on load, reforms off-loadStiff, always flat
    Key CausesLaxity, early PTTDTarsal coalition, advanced arthritis
  • PTTD Stages (Johnson & Strom Classification):

Clinical Assessment - Spotting the Signs

  • Symptoms:
    • Medial ankle/hindfoot pain, fatigue.
  • Key Physical Signs:
    • "Too many toes" sign: >2-3 toes visible laterally (posterior view) → forefoot abduction.
    • Heel Rise Test (Single/Double): Difficulty/pain, hindfoot remains in valgus (Posterior Tibial Tendon Dysfunction - PTTD).
    • Forefoot abduction, Hindfoot valgus.
  • Radiographic Evaluation (Weight-bearing views):
    • Views: AP, Lateral, Hindfoot alignment (e.g., Saltzman).
    • Key Angles:
      • Meary's Angle (Lat): $angle(talus_long_axis, first_metatarsal_long_axis)$. Normal: . Apex plantar in flatfoot.
      • Talonavicular Coverage Angle (AP): Normal: < . ↑ indicates talar subluxation.
      • Calcaneal Pitch (Lat): Normal: 20-30°. ↓ in flatfoot (e.g., < 18°). Calcaneal Pitch Angle on Lateral Foot X-ray

⭐ The "too many toes" sign, seen from posterior, is indicative of forefoot abduction and hindfoot valgus.

Management Strategies - Fixing Flat Feet

Conservative:

  • Activity modification, NSAIDs
  • Orthotics: UCBL, SMO
  • Physiotherapy

Surgical (Indications: Failed conservative, progressive deformity, pain):

  • Soft Tissue:
    • PTT repair/debridement
    • FDL transfer to navicular
    • Spring ligament repair
  • Osteotomies:
    • MDCO
    • LCL (Evans)
    • Cotton (medial cuneiform)
  • Arthrodesis: Subtalar, talonavicular, double, triple

PTTD Stage-Specific Management:

  • I: Conservative (NSAIDs, orthotics, PT).
  • II (Flexible deformity):

    ⭐ FDL (Flexor Digitorum Longus) tendon transfer is commonly used to substitute for the dysfunctional PTT in flexible flatfoot (Stage II PTTD).

    • FDL transfer, PTT debridement/repair, spring lig. repair ± osteotomies (MDCO, Evans, Cotton), ± gastroc recession.
  • III (Rigid deformity): Arthrodesis (e.g., triple).
  • IV (Ankle valgus/arthritis): Arthrodesis (triple/pantalar) ± deltoid repair.

High‑Yield Points - ⚡ Biggest Takeaways

  • Flexible flatfoot is common in children, often self-correcting; rigid flatfoot is pathological.
  • Posterior Tibial Tendon Dysfunction (PTTD) is the most common cause of Adult Acquired Flatfoot Deformity (AAFD).
  • "Too many toes" sign is a key indicator for AAFD/PTTD.
  • Tarsal coalition (e.g., talocalcaneal) is a primary cause of adolescent rigid flatfoot.
  • Jack's test assesses hindfoot flexibility; arch restoration indicates flexible flatfoot.
  • Important radiographic angles: Meary's angle, calcaneal pitch, talar declination angle.

Practice Questions: Flatfoot Deformities

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Deltoid ligament is attached to all, except which structure?

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Flashcards: Flatfoot Deformities

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Hallux valgus leads to overriding of the _____ finger and prominence of the 1st MTP head

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Hallux valgus leads to overriding of the _____ finger and prominence of the 1st MTP head

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