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Bunion (Hallux Valgus)

Basics

  • Lateral deviation of great toe; medial deviation of 1st metatarsal
  • Medial prominence at 1st metatarsophalangeal (MTP) joint ("bunion")
  • Progressive subluxation of 1st MTP joint in late stages

Epidemiology

  • More common in adults; female to male ratio ~2:1
  • Commonly bilateral
  • Prevalence increases with age: 23% in adults 18-65; 36% in elderly >65
  • Juvenile cases more common in girls (>80%)

Etiology and Pathophysiology

  • Multifactorial: abnormal anatomy + repetitive external forces
  • Absence of stabilizing muscles allows lateral deviation of proximal phalanx, medial deviation of 1st metatarsal
  • Medial MTP joint capsule and collateral ligament stretched/ruptured → decreased stability
  • Lateral collateral ligaments contract; abductor hallucis migrates causing plantar flexion and lateral pronation
  • Genetic predisposition supported by twin and genome-wide association studies

Risk Factors

  • Genetic predisposition
  • Abnormal biomechanics: flexible flat feet, hindfoot pronation, Achilles tendon tightness
  • Foot deformities: pes planus, metatarsus primus varus
  • Amputation of 2nd toe
  • Inflammatory joint disease, neuromuscular disorders (CP, stroke)
  • Improper footwear: high heels, narrow toe box

Associated Conditions

  • Medial bursitis of 1st MTP joint
  • Hammertoe of 2nd phalanx
  • Plantar callus, metatarsalgia
  • Cartilage degeneration of 1st metatarsal head and sesamoids
  • Onychocryptosis (ingrown toenail)
  • Synovitis of MTP joint
  • Entrapment of medial dorsal cutaneous nerve

Diagnosis

History

  • Pain at MTP joint (most common symptom)
  • Medial “bump” or prominence
  • Difficulty fitting shoes, pain with ambulation
  • Skin irritation, blisters, callus at 1st MTP

Physical Exam

  • Antalgic gait due to pain
  • Medial prominence at MTP joint
  • Erythema, blistering, callus, ulceration at MTP
  • Great toe overridding or underriding 2nd toe
  • Examine 1st MTP range of motion, 1st tarsometatarsal joint mobility
  • Check neurovascular status, signs of osteoarthritis

Differential Diagnosis

  • Trauma: turf toe, sesamoiditis, stress fracture
  • Infection: osteomyelitis, septic arthritis
  • Joint disorders: osteoarthritis, rheumatoid arthritis, gout, pseudogout
  • Tendon disorders: tendinosis, tenosynovitis, tendon rupture
  • Others: bursitis, ganglion cyst, foreign body granuloma

Diagnostic Tests

  • Weight-bearing AP and lateral foot radiographs; sesamoid view optional
  • Assess joint congruency, degenerative changes, sesamoid displacement
  • Radiographic angles:
  • Hallux valgus angle (HVA) <15° normal
  • Intermetatarsal angle (IMA) <9° normal
  • Distal metatarsal articular angle (DMAA) <8° normal
  • Hallux valgus interphalangeal angle (IPA) <10° normal

Treatment

Indications

  • Primary indication: pain relief

General Measures

  • Proper fitting footwear (low-heeled, wide toe box)
  • Orthotics for foot alignment correction
  • Splinting (limited evidence) to stabilize MTP joint
  • Foot mobilization and exercise combined with toe separators for pain and range of motion improvement
  • Pads and toe spacers to reduce friction and pain

Medications

  • Topical and oral NSAIDs, acetaminophen for pain
  • Capsaicin cream as topical option
  • Corticosteroid injections rarely used outside postoperative setting

Referral

  • Surgery indicated for severe pain, dysfunction, or refractory symptoms

Surgery

  • Over 150 surgical techniques; no consensus on superior method
  • Choice depends on severity, radiographic findings, patient/surgeon factors
  • Options include:
  • Arthrodesis (1st MTP fusion) for severe/recurrent deformity
  • Arthroplasty (joint removal/replacement, high revision rate)
  • Exostectomy/bunionectomy (medial prominence removal)
  • Soft tissue realignment (for minor deformities or adjunct)
  • Osteotomy and realignment (distal for mild-moderate; proximal for severe)
  • Mini TightRope procedure using FiberWire for alignment correction
  • Pediatric surgery delayed until skeletal maturity

Complementary Medicine

  • Marigold ointment may reduce pain and soft tissue swelling

Ongoing Care

  • Postoperative physical therapy, physiotherapy, supportive footwear
  • Continuous passive motion or manual manipulation post-surgery
  • Full weight-bearing timing varies by surgical procedure

Prognosis

  • Outcome varies with biomechanics, deformity severity, and treatment
  • Recurrence after surgery ~25%, increased with higher pre/postoperative HVA, IMA, sesamoid position

Complications

  • Surgical: infection, persistent pain, poor cosmetic results
  • Other: swelling, hallux varus, recurrence, metatarsal fracture, decreased sensation