Ingrown Toenail

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Description

  • In an ingrown toenail, the distal margin of the nail plate grows into the lateral nail fold, causing irritation, inflammation, and sometimes bacterial or fungal infection:
    • Stage 1 (inflammation): erythema, edema, tenderness of lateral nail fold
    • Stage 2 (abscess): granuloma (inflamed tissue) at edges, drainage (serous or purulent)
    • Stage 3 (chronic inflammation): chronic inflammation with continued purulence with granulation tissue growing over the nail plate and significant nail fold hypertrophy
  • Can reoccur
  • Synonym(s): onychocryptosis, unguis incarnatus

Epidemiology

  • Great toenail is most often affected.
  • Lateral edge of nail is affected about twice as much as the medial edge.
  • Most common in males aged 14 to 25 years
  • Infrequent, but more often in elderly females than in elderly males
  • More common in those with lower incomes

Prevalence

  • 2.5–5.0% of total population
  • 5% of population aged >65 years
  • 2:1 male-to-female ratio

Etiology and Pathophysiology

  • Nail plate penetrates the nail fold, causing a foreign body reaction (inflammation).
  • Bacteria or fungi may enter through the opening in the nail fold, causing infection and abscess formation.
  • The inflamed and infected area leads to granulation tissue and hypertrophy of the nail fold.

Risk Factors

  • Genetic factors
    • Increased nail fold width
    • Decreased nail thickness
    • Medial rotation of the toe
  • Factors that may increase risk:
    • Distorted, thickened nail (onychogryphosis)
    • Fungal infection (onychomycosis)
    • Hyperhidrosis
    • Obesity
    • Improper trimming of the lateral nail plate
    • Poorly fitting shoes
    • Trauma to nail or nail fold
    • Conditions that predispose to pedal edema (i.e., thyroid dysfunction, diabetes, obesity, heart failure, renal disease)

General Prevention

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