Flatfoot In Adults 2

Modern Study Review (AI-Generated)

High-Yield Summary

Adult acquired flatfoot deformity (AAFD) is most commonly caused by Posterior Tibial Tendon Dysfunction (PTTD), a progressive degenerative condition leading to collapse of the medial longitudinal arch and hindfoot valgus. Early recognition and staging are critical to guide treatment, which ranges from conservative management to complex reconstructive surgery. Understanding the biomechanics of the tibialis posterior and its antagonists is essential for restoring foot alignment and function.

Key Diagnostic Findings

Current Gold Standard Treatment

Modern Complications & Outcomes

• Complications: Nonunion after arthrodesis, persistent pain, overcorrection or undercorrection of deformity, tendon transfer failure if foot is rigid, adjacent joint arthritis.
• Outcomes: Early-stage reconstruction yields excellent pain relief and functional restoration; arthrodesis provides durable correction but limits hindfoot motion.
• Board Exam Pearls:
• Single-leg heel raise test is pathognomonic for PTTD dysfunction.
• Tendon transfer (FDL) is contraindicated in rigid deformities.
• Triple arthrodesis corrects hindfoot valgus but sacrifices subtalar motion.
• Rheumatoid arthritis often affects forefoot and ankle, requiring early surgical intervention before severe deformity.

Classic Clinical Notes

Posterior Tibial Tendon Dysfunction

• Tib post inserts into the plantar aspect of the navicular and into the medial and middle cuneiforms.
• Main function: invert the subtalar joint (stabilizes hindfoot with gastrocnemius) and adduct the forefoot; inverting the heel stabilizes the subtalar joint.
• Peroneus brevis is the main antagonist, everting the subtalar joint and abducting the forefoot.
• If tib post is weak, peroneus brevis acts as a significant deforming force; conversely, if peroneus brevis is disrupted, hindfoot is pulled into varus and forefoot into adduction by tib post.
• Tib post dysfunction is largely degenerative, preceded by synovitis.
• History: slow progressive discomfort.
• Physical exam: significant sagging of medial malleolus and talar head, forefoot abducted; standing on toes is difficult, calcaneus will not invert.
• Ankle joint motion usually good; subtalar and transverse tarsal motion variable—important for treatment planning.
• Muscle strength tested by resisted inversion in plantarflexion (to reduce tibialis anterior influence) and maximal eversion.
• Assess forefoot-hindfoot relationship; hindfoot valgus may cause forefoot varus, which can become fixed and require correction.

Approach

• Careful physical exam to note synovial thickening, subtalar, ankle, and transverse tarsal motion, and degree of hindfoot vs forefoot rotation.
• If synovitis is major problem: NSAIDs and cast immobilization.
• If chronic and rigid: foot orthosis.
• If flexible: orthosis or UCBL insert.
• Surgery: reconstruction or fusion.
• Reconstruction requires supple hindfoot and forefoot; tendon transfer fails if mobility absent or forefoot varus advanced.
• Tendon transfer preferred in young patients with supple feet.
• Mann’s technique: reconstruct tib post with flexor digitorum longus strung into navicular.
• Arthrodesis: more flexible foot correlates with less disability.
• Fusion options depend on anatomy:
• Isolated subtalar fusion if supple, correctable transverse tarsal joint and no fixed forefoot deformity.
• Talonavicular arthrodesis if subtalar joint and forefoot flexible.
• Double arthrodesis (talonavicular and calcaneocuboid) if subtalar joint supple.
• Triple arthrodesis to restore hindfoot to neutral or 5° valgus.

Rheumatoid Arthritis

• Predilection for forefoot and ankle involvement.
• Rarely involves tarsometatarsal joints.
• Treatment: immobilization, possibly ankle-foot orthosis (AFO).
• Surgery should be aggressive before large deformity develops.

Last Updated on January 24, 2026 by orthonet