Description

• In 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, slight edema, tenderness of lateral nail fold
  • Stage 2 (abscess): Increased pain, erythema, and edema, as well as drainage (purulent or serous)
  • Stage 3 (granulation): Further increased erythema, edema, and pain, with granulation tissue growing over the nail plate
• Can be recurrent
• Synonym(s): Onychocryptosis

Epidemiology

• Great toenail is almost exclusively affected.
• Lateral edge of nail is more commonly affected than the medial edge.
• Most common in males aged 16–25 years
• More common in elderly females than in elderly males
• More common in those with lower incomes

• 24.5/1,000 overall
• 50/1,000 ≥65 years

Risk Factors

• Genetic factors:
  • Increased nail fold width
  • Decreased nail thickness
  • Medial rotation of the toe
• Many others proposed; none proven, including:
  • Distorted, thickened nail (onychogryphosis)
  • Fungal infection (onychomycosis)
  • Hyperhidrosis
  • Improper trimming of the lateral nail plate
  • Poorly fitting shoes
  • Trauma to nail or nail fold

General Prevention

• Properly fitting shoes
• Proper nail trimming

Pathophysiology

• Nail plate penetrates the nail fold.
• This causes 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 tissue hypertrophies, further covering the nail plate.