An ingrown nail (onychocryptosis) occurs when the edge of the toenail digs into, and pierces, the skin adjacent to the nail. The skin may present as inflamed, swollen and is almost always tender. Opportunistic infections can occur from the normal skin flora. Infection always exacerbates the lesion as further swelling gives rise to further pressure and a likelihood of increased penetration of the nail.
The debilitating effects of an ingrown nail must never be underestimated. One of the first papers published on the operative management captures the sentiment well. “One of the most painful and incapacitating conditions encountered in the field of minor surgery, which can be relieved with gratifying results by proper surgical treatment, is the ingrown toenail” (Winograd 1929)
Studies in the United Kingdom have shown a 2:1 male to female ratio, most commonly affecting patients aged 16-25 years old (Langford 1989). In the USA the 1990 National Health Survey showed a 2:1.5 male to female ratio for patients younger than 45 years old; with increasing age more female patients suffered. Over 75 years of age the male to female ratio reduced to 1:1.6. (Levy 1992).
Ingrown nails have been reported to occur for a variety of reasons:
- Ill-fitting footwear
- Tight socks
- Soft tissue abnormalities of the toe
- Abnormal foot mechanics
- Excessive sweating (hyperhydrosis)
- Incorrect trimming of the nail (cutting, or not cutting, the lateral nail edge)
Langford (1989) concurred with Lloyd-Davies but also included:
- Thick nail folds
- Medial rotation of the hallux (eversion)
- Reduced nail thickness
Diabetic patients have been found to have a higher incidence of ingrown nails compared with non-diabetic patients (Riviera 1998).
Ingrown nails have been reported to occur secondary to medicinal intervention. Patients with HIV infection, being treated with protease inhibitors have presented with multiple ingrown nails. Indinavir is the main protease inhibitor that has been implicated (Bouscarat 1998, Alam M 1999, Bourezane 1999). The immunosuppressive drug, Cyclosporin has been associated with the development of ingrown nails (Olujohungbe 1993). Similarly oral antifungal treatment has been associated with ingrown toenails (Connelly 1999), (Weaver and Jespersen 2000).