e5-06: Onychocryptosis (Ingrown Nail)

Onychocryptosis is a common condition that occurs when the nail plate traumatizes periungual skin, which can cause inflammation that can eventually lead to infection (Figure E5–4). It commonly affects the great hallucal toenails but can also occur in the lesser digital nail plates. The occurrence of this disorder is more common in teenagers, with increasing prevalence throughout life. Women are at greater risk for developing an ingrown toenail secondary to wearing narrow shoe gear.

Ingrown toenails are caused by a combination of factors including improper nail care and hygiene, genetic predisposition, chronic trauma, aberrant nail anatomy, poorly fitting shoe gear, soft tissue abnormalities, and hyperhidrosis. The most common cause is improper trimming that can lead to a spike of nail that anchors into the soft tissue. This can cause local inflammation, formation of a granuloma, hypertrophy of the nail fold, and infection.

Ingrown toenails can be classified into three stages: mild, moderate, and severe. In mild cases, there is pain with pressure, nail fold swelling, edema, and erythema. Moderate cases display increasing edema, erythema, warmth, seropurulent drainage, and ulceration of the nail fold. In severe cases, there is chronic inflammation and formation of granulation tissue with associated nail fold hypertrophy.

In general, an ingrown toenail is not a self-limiting problem and requires proper treatment for resolution.

A. Conservative

Nonsurgical intervention is most beneficial when the ingrown toenail is mild or moderate. This includes soaking the toe in warm water for 10–20 minutes, application of topical antibiotic ointment, or placing cotton wisps under the ingrown nail edge.

B. Surgical

Surgical interventions are more effective than conservative management in preventing recurrence of an ingrown toenail. The most common surgical procedure to treat a locally infected ingrown toenail is a partial nail avulsion of the affected nail in conjunction with a chemical matricectomy (the process of destroying all or part of the nail base or nail matrix) using 89% phenol or 10% sodium hydroxide. Other surgical procedures include radical excision of the nail fold, wedge resection, and total nail avulsion. Alternative methods include partial matricectomy using electrocautery, radiofrequency, and carbon dioxide laser ablation but are less common and more expensive.

Possible complications include regrowth of the nail spicule, infection, and damage to the nail matrix. There is no evidence supporting the use of antibiotics to prevent postoperative infections.

A referral to a podiatrist should be made to prevent spread of infection, especially in diabetic and immunocompromised patients.