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
  • Gender difference: female > male by ~2:1
  • More common in shoe-wearing populations
  • Commonly bilateral

Incidence
Unknown and difficult to assess

Prevalence
  • Prevalence increases with age, particularly in females.
  • Adults (age 18 to 65 years): estimated prevalence of 23%
  • Elderly (>65 years) adults: estimated prevalence of 35.7%
  • Juvenile hallux valgus: more common in girls (>80% of cases)

Etiology and Pathophysiology

Multifactorial and controversial. Contributing factors may include underlying anatomy and repetitive external forces:

  • Absence of muscles that directly stabilize the 1st MTP allows relatively unopposed forces to influence lateral deviation of the proximal phalanx and medial deviation of the 1st metatarsal head.
  • Medial MTP joint capsule and medial collateral ligament are chronically stretched and may eventually rupture, decreasing stability and causing progressive subluxation of the 1st MTP joint.
  • Lateral joint capsule and collateral ligaments also contract.
  • Lateral and plantar migration of abductor hallucis muscle moves the great toe into plantar flexion and lateral pronation.
Genetics
  • Cohort and twin studies suggest heritability
  • Genome wide association studies suggest sex-specific differences in genetic mechanisms

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 (hallux rigidus)
  • Pronated feet; ankle equinus
  • Onychocryptosis (ingrown toenail)
  • Entrapment of the medial dorsal cutaneous nerve
  • Synovitis of the MTP joint

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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
  • Gender difference: female > male by ~2:1
  • More common in shoe-wearing populations
  • Commonly bilateral

Incidence
Unknown and difficult to assess

Prevalence
  • Prevalence increases with age, particularly in females.
  • Adults (age 18 to 65 years): estimated prevalence of 23%
  • Elderly (>65 years) adults: estimated prevalence of 35.7%
  • Juvenile hallux valgus: more common in girls (>80% of cases)

Etiology and Pathophysiology

Multifactorial and controversial. Contributing factors may include underlying anatomy and repetitive external forces:

  • Absence of muscles that directly stabilize the 1st MTP allows relatively unopposed forces to influence lateral deviation of the proximal phalanx and medial deviation of the 1st metatarsal head.
  • Medial MTP joint capsule and medial collateral ligament are chronically stretched and may eventually rupture, decreasing stability and causing progressive subluxation of the 1st MTP joint.
  • Lateral joint capsule and collateral ligaments also contract.
  • Lateral and plantar migration of abductor hallucis muscle moves the great toe into plantar flexion and lateral pronation.
Genetics
  • Cohort and twin studies suggest heritability
  • Genome wide association studies suggest sex-specific differences in genetic mechanisms

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 (hallux rigidus)
  • Pronated feet; ankle equinus
  • Onychocryptosis (ingrown toenail)
  • Entrapment of the medial dorsal cutaneous nerve
  • Synovitis of the MTP joint

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