Bunion (Hallux Valgus)

Bunion (Hallux Valgus) is a topic covered in the 5-Minute Clinical Consult.

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Basics

Description

  • Lateral deviation of the great toe (“Hallux abducto valgus” derives from the Latin for “big toe askew.”)
  • Associated medial deviation of the 1st metatarsal, leading to a medial prominence of the 1st metatarsophalangeal (MTP) joint (also known as “bunion”)
  • Progressive subluxation of the 1st MTP joint in later stages
  • System(s) affected: musculoskeletal/skin

Epidemiology

  • Predominant age: more common in adults
    • Estimated 23% in adults aged 18 to 65 years
    • Estimated 35.7% in elderly >65 years
  • Predominant sex: female > male by ~2:1

Prevalence
  • Prevalence increases with age particularly in females.
  • Juvenile hallux valgus
    • More common in girls (>80% of cases)
  • Commonly bilateral

Etiology and Pathophysiology

Multifactorial. Contributing factors include the following:

  • Valgus deviation of the hallux promotes varus position of the 1st metatarsal.
  • Medial MTP joint capsule stretches and attenuates, whereas the lateral capsule contracts.
  • Metatarsal head moves medially, shifting the sesamoid bones to a more lateral position.
  • Extensor hallucis longus deviates laterally.
  • Lateral and plantar migration of abductor hallucis moves the great toe into plantar flexion and lateral pronation.
  • Medial collateral ligament stretches and eventually ruptures, decreasing stability and causing progressive subluxation of the 1st MTP joint.

Risk Factors

  • Genetic predisposition
  • Abnormal biomechanics (i.e., flexible flat feet)
  • Foot deformities: joint laxity, hindfoot pronation, Achilles tendon tightness, pes planus (fallen arches), metatarsus primus varus
  • Amputation of 2nd toe
  • Inflammatory joint disease
  • Neuromuscular disorders (cerebral palsy, stroke)
  • Improper footwear (high heels; narrow toe box)

General Prevention

Proper footwear may decrease the progression of the disease.

Commonly Associated Conditions

  • Medial bursitis of the 1st MTP joint (most common)
  • Hammertoe deformity of the 2nd phalanx
  • Plantar callus
  • Metatarsalgia
  • Degeneration of 1st metatarsal head cartilage
  • Pronated feet; ankle equinus
  • Onychocryptosis (ingrown toenail)
  • Entrapment of the medial dorsal cutaneous nerve
  • Synovitis of the MTP joint

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