Ingrown Toenail

Ingrowing nail (onychocryptosis) is the penetration of the lateral nail edge into the adjacent nail fold, producing inflammation, pain, granulation tissue and sometimes infection. It affects the great toe in most cases.

• Causes:
  • Incorrect nail cutting (cut too short, or rounded corners that leave a spicule).
  • Tight or narrow shoes.
  • Trauma and repetitive pressure (football, ballet, running).
  • Hyperhidrosis and poor foot hygiene.
  • Nail shape (a curved or pincer nail, a wide nail on a narrow bed, a large toe fold).
  • Obesity and oedema, hallux valgus, and onychomycosis.
  • Drug induced (isotretinoin, retinoids, EGFR inhibitors, indinavir, taxanes, ciclosporin).
• It is commonest in adolescents and young adults, and in the elderly in whom it is associated with thick nails (onychogryphosis) and poor nail care.
• Without treatment it recurs or progresses, causing cellulitis, abscess and, in the diabetic or vascular foot, osteomyelitis and gangrene.

• Three stages are used clinically:
  • Stage 1: erythema, mild swelling and pain with pressure of the nail fold.
  • Stage 2: more swelling, drainage, infection and pain at rest.
  • Stage 3: chronic disease with hypertrophic granulation tissue overgrowing the nail fold and lateral nail margin, and fibrosis.
• Pain on walking and wearing shoes, with a lateral nail spike, discharge of pus or serous fluid, and bleeding.
• Fever, spreading erythema and lymphangitis indicate cellulitis.
• Differential diagnosis: paronychia, pyogenic granuloma (a bleeding vascular nodule, often in drug induced or traumatic cases), subungual exostosis (a bony prominence under the nail), glomus tumour, onychomycosis, subungual melanoma, squamous cell carcinoma, herpetic whitlow, and foreign body.
• Complications: cellulitis, abscess, osteomyelitis of the distal phalanx, granuloma, recurrent infection, nail deformity, and in diabetes, ulceration and gangrene.

• Clinical. Inspect the nail and nail fold with the patient standing, check footwear and cutting habits, and ask about drugs and trauma.
• Swab any pus. X-ray the toe if osteomyelitis, a subungual exostosis, or a foreign body is suspected.
• In diabetes, peripheral vascular disease or neuropathy, check pulses, capillary refill, sensation and glycaemic control (HbA1c), and measure the ankle brachial pressure index.
• Biopsy of persistent granulation tissue that does not resolve after treatment, to exclude amelanotic melanoma and squamous cell carcinoma.

• Conservative treatment (stages 1 and 2 without abscess):
  • Warm water soaks with a mild antiseptic or salt (1 teaspoon per 250 mL) for 10 to 15 minutes, 3 times daily.
  • Gently lift the nail edge and place a small piece of cotton wool, dental floss or a gutter splint (a split plastic tube) under the corner, changing it daily, to guide the nail to grow over the skin edge.
  • Taping the nail fold away from the nail edge with adhesive tape, pulling the fold downward and away.
  • Wear wide, open shoes or sandals, and keep the toe dry.
  • Cut the nail straight across, leaving the corners visible, and avoid cutting into the sides.
  • Analgesia with paracetamol 1 g orally 6 hourly (maximum 4 g per day) and ibuprofen 400 mg orally 8 hourly with food if no contraindication.
  • Topical mupirocin 2% ointment or fusidic acid 2% cream twice daily for 5 to 7 days for mild infection.
• Oral antibiotics only for cellulitis or systemic signs (they do not treat the cause, and are ineffective alone):
  • Flucloxacillin 500 mg orally 6 hourly for 5 to 7 days (child 12.5 to 25 mg/kg 6 hourly).
  • Cefalexin 500 mg orally 6 hourly.
  • Clindamycin 300 to 450 mg orally 8 hourly in penicillin allergy or for suspected MRSA.
  • Diabetic or vascular patients with infection need broader cover and urgent review.
• Surgical treatment, for failure of 4 to 6 weeks of conservative care, or for stage 2 and 3 disease, abscess or recurrent disease. It is a minor procedure done under digital ring block.
  • Digital block: lidocaine 1 to 2% plain (never with adrenaline) 2 to 3 mL at each side of the base of the toe, with a total of 5 to 6 mL and a maximum of 4.5 mg/kg. Alternatively, bupivacaine 0.5% plain, 2 to 3 mL per side, for longer lasting analgesia (maximum 2 mg/kg). A tourniquet at the base of the toe provides a bloodless field, with a limit of 20 minutes.
  • Partial nail avulsion: slide a nail elevator under the offending edge, cut a 2 to 3 mm longitudinal strip of nail to the proximal nail fold, and remove it along with any granulation tissue and spicule. Nail avulsion alone recurs in 20 to 70% of patients.
  • Chemical matrixectomy with phenol (the preferred addition, as it lowers recurrence to about 2 to 10%): apply 80 to 89% liquid phenol on a cotton bud to the exposed matrix horn for 30 seconds, repeated 2 to 3 times (a total contact time of 1 to 1.5 minutes), then neutralise with isopropyl alcohol or saline, and protect the surrounding skin with petroleum jelly. Expect weeping for 2 to 6 weeks.
  • Sodium hydroxide 10% for 1 minute, as an alternative chemical agent (evidence is limited).
  • Surgical matrixectomy: wedge resection of the nail matrix, or total nail avulsion with matrix excision for recurrent or severe cases. Recurrence is about 2 to 10%.
  • Excision of hypertrophic granulation tissue with silver nitrate cauterisation, or hypertrophic nail fold (wedge) excision for stage 3 disease.
  • Drain any abscess, and send pus for culture.
  • Dressing: petroleum gauze with a light bandage, changed after 24 to 48 hours, then daily soaks for 2 to 4 weeks until healed.
  • Check the tetanus immunisation status.
• Do not use phenol in patients with poor perfusion of the toe (peripheral arterial disease, ankle brachial pressure index below 0.5), in those with active infection that is not controlled, or where healing will be impaired. Perform surgical treatment in diabetes only with a healing assessment and a low threshold for specialist referral.
• Special groups:
  • Children and adolescents: conservative care first, with partial avulsion and phenol under local anaesthesia (lidocaine 1% up to 4.5 mg/kg) or under general anaesthesia for the very young.
  • Pregnancy: use conservative measures. Lidocaine without adrenaline is acceptable. Delay phenol if possible, as systemic absorption is minimal but data are limited.
  • Diabetes and arterial disease: refer to a podiatrist or vascular surgeon. Infections can progress rapidly.
  • Anticoagulation: continue anticoagulants for minor procedures and use local pressure, and review the dose of antiplatelet agents. Take the time to ensure haemostasis.
  • Immunosuppression: treat infection early and use a longer antibiotic course.
  • Drug induced disease: review the causative drug with the prescriber.
• Prevention: cut nails straight across, wear well fitting shoes, keep the feet clean and dry, avoid picking at corners, and treat onychomycosis and hyperhidrosis.
• Follow up: review at 1 to 2 weeks after surgery, and again at 6 weeks. Refer to podiatric or orthopaedic surgery for recurrent disease or failure of a first matrixectomy, and to dermatology for a persistent granuloma or suspected malignancy.