Onychogryphosis

Definition: Onychogryphosis, also known as ram’s horn nail, is a nail disorder characterized by slow nail plate growth, opaque yellow-brown thickening, elongation, and increased curvature of the nail plate.

Demographics

• Congenital: Rare, but reported in some genodermatoses.
• Acquired: More common, often seen in older individuals, people with poor personal care, and patients with senile dementia.

Causes

• Skin Diseases: Ichthyosis, psoriasis, pemphigus, tertiary syphilis, hyperuricaemia, smallpox (historical).
• Poor Peripheral Circulation: Often associated with diabetes mellitus.
• Traumatic Injury: Nail bed injuries or microtrauma from poorly fitting shoes.
• Hallux Valgus: Bunion deformity.

Clinical Features

• Nail Involvement: Typically affects one or both great toenails but can involve any nail.
• Appearance: Opaque, yellow-brown thickening with a ‘ram’s horn’ or ‘oyster-like’ appearance.
• Nail Growth: Nail plate grows upwards and deviates laterally, with an irregular nail bed surface marked by transverse striations.

Complications

• Ingrown Toenail: Nail grows into the surrounding skin.
• Paronychia: Infection of the skin around the nail.
• Secondary Onychomycosis: Fungal nail infection.
• Subungual Gangrene: Rarely occurs.

Diagnosis

• Clinical Diagnosis: Based on characteristic appearance.
• Histology: Shows disorderly keratinocytes, hyperchromatism, parakeratosis, and numerous splits.

Differential Diagnoses

• Congenital Malalignment of Toenails: Lateral deviation of the nail plate in infancy or childhood.
• Pachyonychia Congenita: Thickened nails with brownish discoloration; molecular genetic studies for keratin gene mutations.
• Onychomycosis: Co-existing fungal infection; nail clippings for culture.

Treatment

• Conservative Treatment:
  • Properly fitted footwear to reduce pressure and trauma.
  • Regular use of electric drills, burs, or mechanical debridement with nail clippers.
  • Cryotherapy prior to debridement to soften the nail plate.
  • Blunt dissection after medical nail avulsion with 40% urea or 50% potassium iodide.
• Operative Treatment:
  • Nail avulsion followed by ablative or excisional matricectomy.
  • Excisional techniques: Scalpel excision, cutting electrosurgery, or laser.
  • Ablative techniques: Chemical cautery, electrosurgery, or laser in ablative mode.
  • Zadik technique or V–Y advancement flap for complete nail matrix removal.
  • Syme method (rare): Removal of half the terminal phalanx with the nail fold.

Outcome

• Recurrence: Tends to recur after conservative treatment.
• Management: Regular treatment to keep the nail bed short and prevent complications. Proper footwear is crucial to prevent excessive nail pressure.