Nail Conditions in Sport

Repetitive trauma to the toenails, classically from the toe striking the front of the shoe when running downhill or in shoes that are too short, causes bleeding under the nail. This subungual haematoma, sometimes called runner's toe or tennis toe, usually affects the great or second toe and can be acutely painful because blood is trapped under pressure in an enclosed space. A single crushing injury, such as a dropped weight, causes the same thing more dramatically.

An acutely painful subungual haematoma seen within a day or two can be relieved by trephination, making a small hole in the nail plate to release the trapped blood and ease the pressure, which quickly relieves the pain. Haematoma size alone is not a reason to remove the nail: a large but uncomplicated haematoma can usually still be trephined if the nail plate and surrounding folds are intact. Referral is for nail-fold disruption, nail avulsion, a significant nail-bed laceration, or a displaced fracture, which may need the nail bed repairing, and a suspected fracture also needs imaging. Repeated microtrauma also causes onycholysis, where the nail lifts away from the bed, and gradual thickening and distortion of the nail. Most traumatic nail changes are painless once the acute phase settles and simply grow out.

Fungal nail infection, onychomycosis, is common in athletes and often follows athlete's foot, spreading from the skin into the nail. The nail becomes thickened, discoloured and crumbly, usually starting at the distal edge. It is important not to assume every abnormal nail is fungal, since trauma and other conditions look similar and only about half of dystrophic nails are actually infected, so the diagnosis should be confirmed by sending nail clippings and subungual debris for fungal microscopy and culture before starting a long course of treatment. Limited distal disease can be treated with a topical antifungal such as amorolfine nail lacquer, whereas more extensive confirmed dermatophyte infection usually needs oral terbinafine, taken for several weeks for fingernails and longer for toenails, with the usual checks for contraindications, drug interactions and monitoring.

Paronychia is infection of the nail fold. Acute paronychia is usually bacterial, presenting as a red, swollen, painful nail fold that may collect pus; it is treated by draining any abscess and, where needed, an oral antibiotic such as flucloxacillin. Chronic paronychia is largely an irritant dermatitis of the nail fold from repeated wet exposure and irritants, rather than a primary infection. It is managed by avoiding wet work and irritants and using a topical corticosteroid, adding an antifungal only if fungal infection is suspected or confirmed, rather than repeated courses of antibiotics.

An ingrown toenail, onychocryptosis, occurs when the edge of the nail, usually of the great toe, penetrates the surrounding skin, causing pain, redness and sometimes infection and overgrown inflamed tissue. Tight footwear, cutting the nail too short or curved, sweating and trauma all contribute, so it is common in athletes. Early or mild cases can be managed conservatively by cutting the nail straight across rather than rounding it, warm salt-water soaks, careful footwear, and treating any infection. A recurrent or more severe ingrown toenail is treated with a minor procedure to remove the offending edge of nail and to destroy the nail-forming tissue at that edge with a chemical, which gives a lasting result, and this is a reason for referral.

Investigation is usually simple. Fungal nail should be confirmed with clippings for microscopy and culture before oral treatment. Imaging is warranted for a suspected toe fracture under a large haematoma, or for a hard swelling under the nail that could be a bony outgrowth.

The single most important rule with nails is not to mistake a melanoma for a bruise. A subungual haematoma from trauma is tender at first, then grows out with the nail over months, moving distally. A pigmented streak or dark area that appears without a clear injury, that does not grow out and move as expected, that involves the skin of the nail fold, or that is changing, should raise the possibility of a subungual melanoma and be referred urgently for a specialist opinion, since relying on a forgotten minor injury to explain it is a well-recognised trap.

• •Subungual haematoma from repetitive toe trauma is common; trephination relieves an acutely painful one.
• •Size alone does not mandate nail removal; trephine if the nail and folds are intact, and refer for nail-fold disruption, avulsion, nail-bed laceration or displaced fracture.
• •Confirm onychomycosis with nail clippings for microscopy and culture before oral terbinafine.
• •Acute paronychia is bacterial and may need drainage; chronic paronychia needs dryness, not repeated antibiotics.
• •Recurrent ingrown toenail is treated by removing the nail edge with chemical ablation.
• •A pigmented nail without clear trauma, or not growing out, must be referred to exclude melanoma.