Fingernails

Nails are protective coverings on the ends of the fingers and toes. Fingernails and toenails are clear, hard derivatives of the stratum corneum. They are composed of very thin, dead, scaly cells, densely packed together and filled with parallel fibers of hard keratin. Each nail consists of a nail plate, which includes the free edge overhanging the tip of the finger or toe; that overlies a surface of skin called the nail bed. Specialized epithelial cells continuous with the epithelium of the skin produce the nail bed. The nail body, which is the visible attached part of the nail; and the nail root, which extends proximally under the overlying skin. The surrounding skin rises a bit above the nail as a nail fold, separated from the margin of the nail plate by a nail groove. The groove and the space under the free edge accumulate dirt and bacteria and require special attention when scrubbing for duty in an operating room or nursery.

The skin underlying the nail plate is the nail bed; its epidermis is called the hyponychium. At the proximal end of the nail, the stratum basale thickens into a growth zone called the nail matrix. Mitosis in the matrix accounts for the growth of the nail—about 1 mm per week in the fingernails and slightly slower in the toenails. The thickness of the matrix obscures the underlying dermal blood vessels and is the reason why an opaque white crescent, the lunule (lunula), often appears at the proximal end of a nail. A narrow zone of dead skin, the cuticle or eponychium, commonly overhangs this end of the nail.

The appearance of the fingertips and nails can be valuable in medical diagnosis. The fingertips become swollen or clubbed in response to long-term hypoxemia—a deficiency of oxygen in the blood stemming from conditions such as congenital heart defects and emphysema. Dietary deficiencies may be reflected in the appearance of the nails. An iron deficiency, for example, may cause them to become flat or concave (spoonlike) rather than convex. Contrary to popular belief, adding gelatin to the diet has no effect on the growth or hardness of the nails.

Figure 1. Fingernail

Fingernail problems

Fingernail fungus

Onychomycosis is a fungal infection of the fingernails or toenails that causes discoloration, thickening, and separation from the nail bed. Onychomycosis occurs in 10% of the general population but is more common in older adults; the prevalence is 20% in those older than 60 years and 50% in those older than 70 years ¹. The increased prevalence in older adults is related to peripheral vascular disease, immunologic disorders, and diabetes mellitus. The risk of fungal infection of the fingernails or toenails is 1.9 to 2.8 times higher in persons with diabetes compared with the general population ². In patients with human immunodeficiency virus infection, the prevalence ranges from 15% to 40% ³.

Fungal nail infection affects toenails more often than fingernails because of their slower growth, reduced blood supply, and frequent confinement in dark, moist environments. It may occur in patients with distorted nails, a history of nail trauma, genetic predisposition, hyperhidrosis, concurrent fungal infections, and psoriasis. It is also more common in smokers and in those who use occlusive footwear and shared bathing facilities ⁴.

Fungal fingernail infection is caused by various organisms, most often dermatophytes of the genus Trichophyton. Dermatophytes are fungi that require keratin for growth. These fungi can cause superficial infections of the skin, hair, and nails. Other organisms include Candida, which is more common in fingernail infections (Figure 2) and in patients with chronic mucocutaneous candidiasis ¹. Nondermatophyte molds are a less common cause in the general population. Recent studies, however, have demonstrated that they are the predominant organisms in patients with fungal nail infection and human immunodeficiency virus infection ³.

Figure 2. Fingernail fungal infection (Candidal subungual onychomycosis)

Table 1. Common Pathogens in Onychomycosis (Fungal Nail Infections)

Dermatophytes (80% to 90%)

Epidermophyton floccosum

Microsporum species

Trichophyton interdigitale

Trichophyton mentagrophytes

Trichophyton rubrum

Trichophyton tonsurans

Nondermatophyte molds (2% to 10%)*

Acremonium species

Alternaria species

Aspergillus species

Cladosporium carrionii

Fusarium species

Geotrichum candidum

Lasiodiplodia theobromae

Onychocola species

Scopulariopsis species

Scytalidium species

Yeast (2% to 11%)

Candida albicans

Candida guilliermondii

Candida parapsilosis

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[Source ⁵]

Classification of Fungal Nail Infection

Onychomycosis is divided into several classes based on morphologic patterns and mode of invasion of the nail (Table 2) ⁶. Classification provides a framework for diagnosis and expected response to treatment, and can help predict the prognosis. The classes include distal and lateral subungual onychomycosis (Figures 3 and 4), proximal subungual onychomycosis (Figure 5), superficial onychomycosis (Figure 6), and total dystrophic onychomycosis (Figure 7). A fifth class, endonyx subungual onychomycosis, is rare. Some nails have features from a combination of classes.

Table 2. Classification of Fungal Nail Infection

Onychomycosis class	Clinical features	Causative organism*	Mode of infection	Comments
Distal and lateral subungual	Begins distally at the hyponychium and spreads to the nail plate and bed; hyperkeratotic debris accumulates and results in onycholysis; nails thicken, chip, become dystrophic, and turn yellow-white or brown-black; infection can progress proximally, causing linear channels or “spikes” that can make treatment difficult; associated with paronychia	Epidermophyton floccosum	Fungal invasion through break in the skin at the lateral or distal undersurface of the nail	Most common form
		Trichophyton mentagrophytes
		Trichophyton rubrum
		Fusarium species
		Scopulariopsis brevicaulis
		Scytalidium species
		Candida albicans
Endonyx subungual	Nail develops a milky white appearance, indentations, and lamellar splitting; no hyperkeratosis or onycholysis	Trichophyton soudanense	Fungus invades the full thickness of the nail from directly under the skin without infecting the nail bed	Rare; considered a subtype of distal and lateral subungual onychomycosis
		Trichophyton violaceum
Proximal subungual	Debris accumulates under the proximal portion of the nail, causing onycholysis and a white color that spreads distally	T. rubrum	Fungus invades the proximal nail fold and cuticle; may also develop secondary to paronychia	Suggests an immunosuppressive condition (e.g., human immunodeficiency virus infection)
		Aspergillus species
		Fusarium species
		C. albicans
Superficial	Nail appears to have powder-like patches of transverse striae on the surface	T. mentagrophytes	May appear on the superficial nail plate or emerge from under the nail fold; may be deep penetration of the superficial infection	Previously known as superficial white onychomycosis, but some organisms produce black debris
		T. rubrum
		Acremonium species
		Fusarium species
		Scytalidium species
Total dystrophic	Complete destruction of the nail from long-standing infection; nail thickens, and nail structure is lost	—	—	Can result from any of the other classes, although it is most often from severe distal and lateral subungual onychomycosis

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[Source ⁵]

Figure 3. Distal and lateral subungual onychomycosis

Figure 4. Distal and lateral subungual onychomycosis with spike deformity

Figure 5. Proximal subungual onychomycosis

Figure 6. Superficial onychomycosis

Figure 7. Total dystrophic onychomycosis

Accurate diagnosis is crucial for successful treatment and requires identification of physical changes and positive laboratory analysis. Only 50% of nail problems are caused by onychomycosis ⁷, and clinical diagnosis by physical examination alone can be inaccurate. Psoriasis, chronic nail trauma, and other causes must also be considered. The differential diagnosis of onychomycosis is presented in Table 3.

Table 3. Common Conditions That Can Mimic Onychomycosis

Condition	Features
Infections
Chronic paronychia	Chronic inflammation of the proximal paronychium; cross-striations of the nail; Streptococcus, Staphylococcus, or Candida found on smear and culture; common in children
Viral warts	Localized in nail folds and subungual tissue; longitudinal depressed grooves in the nail plate
Skin disorders
Chronic dermatitis	Subungual dermatitis, hyperkeratosis, Beau lines, and pitting; thickened nail with corrugated surface
Lichen planus	Longitudinal grooves and fissures; usually affects fingernails
Psoriasis	Nail pitting, splinter hemorrhages, “oil staining,” yellow-gray or silvery white nails (eFigure B)
Twenty-nail dystrophy	Dystrophy of all 20 nails; usually resolves in childhood; associated with the lesions of lichen planus (eFigure C)
Trauma
Footwear	Oncholysis, ingrown toenails, subungual keratosis, nail plate discoloration and irregularities; caused by friction against the shoe
Manipulation (e.g., manicures, pedicures, rubbing)	Horizontal parallel nail plate grooves, inflammation from Staphylococcus aureus or Pseudomonas infection (eFigure D)
Tumors
Bowen disease	Squamous cell carcinoma; bleeding, pain, nail deformity, and nail discoloration
Fibroma	Oval or spherical, white or yellow nodule; causes tunnel-like melanonychia; fibrous dermatofibroma or periungual fibroma
Melanoma	Brown-yellow nail with dark pigment extending into the periungual skin folds; poor prognosis

[Source ⁵]

Figure 8. Nail pitting in a patient with psoriasis. The pits are enhanced by the presence of grease.

Figure 9. Twenty-nail dystrophy (also called sandpaper nails) is characterized by longitudinal ridges on all 20 nails. The nails may become discolored.

Figure 10. Median nail dystrophy caused by repetitive trauma to the nail from habitual rubbing.

Treatment of fungal nail infection

Onychomycosis is widely believed to be only a cosmetic problem, but it can be uncomfortable and can lead to cellulitis in older adults and foot ulcers in patients with diabetes. Eradication of the infection is key to improving appearance and avoiding these complications, but it is not easily accomplished because nails are made of keratin, which is nonvascular and impermeable to many agents ⁸. Because of poor drug delivery to nails, results of treatment may not be apparent for a year.

Treatment varies depending on the severity of nail changes, the organism involved, and concerns about adverse effects and drug interactions. Treatments also have varying effectiveness, based on cure parameters that are defined differently among studies. Mycotic cure denotes that no organism is identified on microscopy and culture. Clinical cure refers to improvement in the appearance of the nail, often defined as a normal appearance in 80% to 100% of the nail. It is a subjective measure that is difficult to compare across studies ⁹. Complete cure indicates that mycotic and clinical cure have been achieved.

Topical Agents

Several topical agents are used for the treatment of onychomycosis. These agents have few contraindications and no drug-drug interactions.

Ciclopirox 8% solution is the only topical prescription medication available in the United States for the treatment of onychomycosis. It is a synthetic hydroxypyridine antifungal formulated as a nail lacquer. Adverse effects include burning, itching, and stinging at the application site ¹⁰. It may be used in patients who cannot take oral antifungals and in those with less than 50% of the distal nail affected and no lunular involvement ¹¹. It has been used in children, although it is not approved for use in patients younger than 12 years ¹². When used alone, ciclopirox has a mycotic cure rate of 29% to 36%, and a clinical cure rate of 6% to 9% ¹¹. A Cochrane review noted that the treatment failure rate was 61% to 64% after 48 weeks of use ¹³.

Ciclopirox has also been used in combination with oral agents to improve effectiveness. In one comparative study, a combination of ciclopirox and oral terbinafine had a mycotic cure rate of 88% and a complete cure rate of 68%, whereas terbinafine alone had a mycotic cure rate of 65% and a complete cure rate of 50% ¹⁴.

Nonprescription agents have also been used for treatment of onychomycosis. These therapies have been evaluated in only a small number of studies involving few patients. Topical mentholated ointment (Vicks Vaporub) was used in a small study involving 18 patients. After 48 weeks, 28% had mycotic and clinical cure, 56% had partial clearance, and 17% had no improvement ¹⁵. Tea tree oil (Melaleuca alternifolia) has been evaluated in two studies. Although one trial was favorable, combined data from both studies did not demonstrate significant benefit ¹², ¹⁶. Snakeroot extract (Ageratina pichinchensis) is an antifungal derived from plants of the sunflower family. It was studied in a randomized trial involving 96 patients who applied the extract or ciclopirox for six months to nails with confirmed infections ¹⁷. Mycotic cure occurred in 59% of patients receiving the extract and in 64% of those receiving ciclopirox. Clinical cure occurred in 71% and 81% of patients, respectively. Differences between the two treatments were not statistically significant. A small study showed that a combination of cyanoacrylate, undecylenic acid, and hydroquinone (marketed as Renewed Nail) demonstrated mycotic cure in 78 of 154 participants (50%) ¹⁸.

Nail trimming and debridement are often performed concomitantly with other treatments and appear to offer benefit. Study groups that received nail debridement with oral terbinafine had higher clinical cure rates than those who received oral terbinafine alone ¹⁹. When debridement was performed with concurrent administration of ciclopirox, the mycotic cure rate was 77%, higher than that for ciclopirox alone ²⁰. Improvement in nail appearance was reported, but clinical cure rates were not.

Laser and photodynamic therapies

Although they are expensive, laser and photodynamic therapies have become popular based on the success of in-vitro studies. Several neodymium:yttrium-aluminum-garnet (Nd:YAG) laser therapies have been approved by the U.S. Food and Drug Administration for treatment of onychomycosis ²¹. The Pinpointe Foot-laser, Cutera GenesisPlus laser, and Cooltouch Varia laser are short-pulse laser systems, whereas the Light Age Q-Clear laser is a Q-switched laser. However, there are only limited data about the use of these therapies in patients. In one study, Nd:YAG laser light was used to treat 37 nails, with one to three treatments given four to eight weeks apart. At 16 weeks, 61% were completely cured, 19% had significant improvement in the nail appearance, and 11% had moderate improvement in the nail appearance ²².

Another laser treatment, the dual-wavelength near-infrared laser (Noveon), is approved for dermatologic use, but not specifically for treatment of onychomycosis ²³. This treatment was used on 26 nails on days 1, 14, 42, and 120. After 180 days, 91% of nails with mild infection showed clinical improvement (3 to 4 mm of the nail free of clinical infection); however, only 30% had mycotic cure ²⁴.

Photodynamic therapy using photosensitizing drugs and light to destroy fungal cells has shown some success in the treatment of onychomycosis, but further evaluation is needed ²⁵.

Oral Anti-Fungal Medications

Antifungals from the azole and allylamine classes are the most widely used oral medications for the treatment of onychomycosis. The azole class includes itraconazole (Sporanox), fluconazole (Diflucan), and ketoconazole; however, ketoconazole is rarely prescribed because of drug interactions and hepatotoxicity. The allylamine class is represented by terbinafine (Lamisil).

A meta-analysis of treatments for toenail onychomycosis determined that mycotic cure rates were 76% for terbinafine, 63% for itraconazole with pulse dosing, 59% for itraconazole with continuous dosing, and 48% for fluconazole ²⁶. Clinical cure rates were 66% for terbinafine, 70% for itraconazole with pulse dosing, 70% for itraconazole with continuous dosing, and 41% for fluconazole. Common adverse effects included headache, gastrointestinal problems, and rash; these drugs also have been associated with Stevens-Johnson syndrome, prolonged QT interval, and ventricular dysfunction. The use of these agents is discouraged in patients with liver, renal, or heart disease, and in those receiving medications with which there may be significant drug-drug interactions ²⁷. Liver function studies are recommended before beginning treatment and after one month of therapy. A meta-analysis concluded that the risk of asymptomatic elevation of transaminase levels in immunocompetent patients receiving oral antifungal agents was 2%, and that the risk of elevations requiring termination of therapy was 1% ²⁸. Although these medications are not approved for use in children, they have been used in children with positive results ¹².

Dark line on fingernail

The assessment and management of pigmented nail bed lesions can be a significant challenge for clinicians. The difficulty arises from the wide spectrum of differential diagnoses, including potentially life-threatening subungual melanoma.

Figure 1 shows the anatomy of the nail apparatus and location of the nail matrix, an important site for the development of nail bed pathology.

Differential diagnoses of dark line on fingernail could include ²⁹:

• melanocytic lesions
• naevi (moles)
• lentigo (increased single melanocytes)
• melanoma in situ
• melanoma
• subungal squamous cell carcinoma (SCC)
• subungual haemorrhage
• fungal infection
• systemic illness (including systemic lupus erythematosus, scleroderma)
• drug-induced pigmentation
• ethnic-type pigmentation (can often involve multiple digits).

Longitudinal melanonychia is a specific appearance of a linear, pigmented band on the nail plate. This appearance in itself is non-specific and can result from the same variety of diagnoses listed above for any subungual pigmentation. Early subungual melanoma often presents as longitudinal melanonychia.

The differential diagnoses for a patient presenting with a subungual lesion are broad. Lesions can be divided into melanocytic and non-melanocytic. They can also be categorised as neoplastic, traumatic, infective, systemic and drug-induced. Figure 11 illustrates the clinical appearance of some common differentials.

Figure 11. Benign pigmented subungual lesions

Note:  A, C, narrow melanonychia with regular borders and parallel bands of pigment; B, D,corresponding dermatoscopic detail of narrow melanonychia with regular borders and parallel bands of pigment; E, F, subungual haematoma with homogenous reddish brown to black color.

Figure 12. Longitudinal melanonychia (vertical nail bands). These hyperpigmented bands occur as normal variants in 90 percent of black persons ³⁰

The goal of initial assessment is to form an opinion of the likelihood of the lesion being either benign or malignant. This risk assessment guides whether patients are discharged with reassurance that a lesion is benign, enter a short, defined period of serial monitoring, or undergo a biopsy.

Serial monitoring of a lesion with the interval between assessments of 8–12 weeks can be a powerful aid in the management of lesions that are indeterminate on initial assessment. However, time intervals should be individualised and based on the likelihood of malignancy and the patient’s circumstances. The use of dermatoscopy and clinical photography can be particularly helpful and allows for direct comparisons of images obtained over a defined time interval. In cases of subungual haematoma, serial monitoring will often make the diagnosis readily apparent, as the lesion can be observed to migrate distally with normal nail plate growth proximal to the lesion.

Referral to a specialist centre with experience in managing subungual melanoma should be made in cases where the diagnosis remains unclear following a short period of monitoring or in cases where a malignant pathology is suspected from the initial assessment.

Biopsy

Biopsy of a nail bed lesion is a complex procedure. Improperly planned biopsies can risk obtaining an inadequate specimen or damaging the fragile sample of nail matrix so that histopathological examination is compromised. Furthermore, there is the hazard of causing permanent nail dystrophy from injury to the germinal matrix ³¹. As such, referral to a specialist group with experience in managing subungual pathology is often appropriate in cases where a biopsy is being considered.

Fingernail pain

Fingernail pain or paronychia, which can be acute or chronic, (Figure 13A and 13B) is an inflammatory reaction caused by bacterial invasion of the folds of tissue surrounding the nail ³². It is characterized by the rapid onset of erythema, edema, and tenderness at the proximal and lateral nail folds, usually following trauma ³³. Most cases are caused by mixed flora. Staphylococcus aureus and Streptococcus pyogenes are the most common aerobic bacteria associated with paronychia, whereas anaerobic isolates include Bacteroides, Fusobacterium nucleatum, and grampositive cocci ³⁴. Noninfectious causes of paronychia include excessive moisture, contact irritants, and trauma ³³. Psoriasis, Reiter syndrome, and herpetic whitlow should be part of the differential diagnosis of recurrent cases.

Oral antibiotics may be used for severe infections in which an abscess has not developed. Coverage for methicillinresistant S. aureus should be considered in high-prevalence areas, and coverage for anaerobic bacteria should be considered when exposure to oral flora is suspected ³⁵. If an abscess is present, surgical drainage is indicated ³³.

The clinical manifestations of chronic paronychia are similar to those of acute paronychia; however, chronic cases last for more than six weeks. Because of constant infection, the cuticle may separate from the nail plate, forming a space for invasion of various microbes, including bacteria and fungi ³⁵. Patients who are immunosuppressed or who have a systemic illness, such as diabetes or human immunodeficiency virus, are at increased risk of chronic paronychia ³². Treatment includes avoiding exposure to contact irritants and appropriate management of the underlying infection. A broad-spectrum topical antifungal, such as ketoconazole, can be used to treat the superinfection and prevent recurrence when a fungus, such as Candida albicans, is suspected ³².

Paronychia associated with a pseudomonal infection shares many of the same characteristics of acute and chronic paronychia; however, pseudomonal paronychia commonly leads to a green discoloration (Figure 13C). Pseudomonal superinfection is typically caused by repeated minor trauma to the nail apparatus in a chronically wet environment ³². Persons at risk of this condition include bartenders, dishwashers, and habitual nail-biters. Therapy for pseudomonal superinfection should include topical neomycin.

Figure 13. Fingernail pain or paronychia

Note: Paronychia – This condition is an inflammatory reaction caused by bacterial invasion of the folds of tissue surrounding the nail. (A) Acute paronychia is characterized by the rapid onset of erythema, edema, and tenderness at the proximal nail folds. (B) Chronic cases are similar in appearance to acute cases, but last more than six weeks and the cuticle may separate from the nail plate. (C) Paronychia associated with pseudomonal infection is typically caused by repeated minor trauma in a wet environment and often causes a green discoloration.

Fingernail Beau Lines

Beau lines (Figure 14) are horizontal grooves on the nail plate and generally involve most or all of the nails. They reflect an interruption of nail bed mitosis caused by severe illness, pemphigus, high fever, or chemotherapy ³⁶. Beau lines also occur in patients with Raynaud disease. Treatment is aimed at the underlying etiology.

Figure 14. Fingernail Beau Lines

Fingernail Clubbing

Clubbing involves thickening of the nail bed’s soft tissue, particularly in the proximal end (Figure 15A). This condition usually affects all of the fingernails and rarely occurs in a single digit. Clubbing can be clinically diagnosed with an examination showing Schamroth sign1 (Figure 15B; absence of the diamond-shaped opening that normally appears when the digits are opposed). Lovibond angle (Figure 15C; the angle that forms between the nail plate and the soft tissue of the distal digit) is diagnostic of clubbing if it is greater than 180 degrees ³⁷.

The pathogenesis of clubbing is thought to be secondary to altered vasculature. It is theorized that the thickening of the soft tissue develops from increased blood flow within the microvasculature, instead of within the larger capillaries ³⁷. Clubbing can be a sign of numerous underlying diseases, such as cirrhosis, chronic obstructive pulmonary disease or celiac disease.

Figure 15. Fingernail clubbing

Spoon fingernail

Koilonychia (Figure 16) is a condition in which the nail becomes increasingly concave and therefore is often called spoon nail ³⁶. It commonly occurs in association with iron deficiency anemia ³⁷. Koilonychia can be a normal finding in infants, disappearing within the first few years of development ³⁶.

Figure 16. Spoon fingernail (Koilonychia)

Fingernail Mees lines

Mees lines are transverse white lines that may extend the complete width of the nail plate. The lines can occur on a single digit or multiple digits. Mees lines migrate toward the distal end of the nail plate over time because the abnormality is in the nail plate and not the nail bed. The differential diagnosis for Mees lines is narrow, and it is thought to be caused primarily by arsenic poisoning ³⁶. Other heavy metal poisonings and renal failure also may result in Mees lines ³⁸. The timing of the poisoning can be estimated based on the rate of nail plate growth ³⁶.

Figure 17. Fingernail Mees lines

Fingernail Muehrcke Lines

Muehrcke lines (Figure 18) are pairs of transverse white lines caused by localized pathology (e.g., edema from hypoalbuminemia) within the nail bed. Because they originate in the nail bed and not the nail plate, the lines do not migrate distally as the nail grows. The nail bed has abnormal vascular architecture that can be visualized microscopically ³⁶. The lines disappear when pressure is applied to the nail plate because the abnormal blood supply is compressed. If the lines are caused by hypoalbuminemia, the nail findings improve as the underlying condition improves ³⁹.

Figure 18. Fingernail Muehrcke Lines

Pincer fingernails

Pincer nail (Figure 19) is a transverse overcurvature of the nail plate and may be inherited or acquired. The exact etiology is unknown, but the condition has been associated with beta-blocker use, psoriasis, onychomycosis, tumors of the nail apparatus, systemic lupus erythematosus, Kawasaki disease, and malignancy ⁴⁰. If pincer nail is associated with medication use, the nail plate returns to normal after cessation of the medication ⁴¹. Surgical treatment modalities include nail bed cutting with or without splinting ⁴².

Figure 19. Pincer fingernais

Fingernail Splinter hemorrhage

Splinter hemorrhages (Figure 20) are red-brown, longitudinal lines occurring in the nail bed (not the nail plate) that develop secondary to leaky capillaries ³⁶. When pressure is applied to the nail, they do not disappear because the lines are caused by blood that has leaked out of the vasculature ³⁷. Splinter hemorrhages historically have been associated with endocarditis, typically appearing in the midportion of the nail. However, only 15 percent of patients with endocarditis have them ³⁶ and other causes of proximal nail bed splinter hemorrhages should be considered. Many causes of the condition have been identified. The most common cause is trauma, which often leads to distal nail bed splinter hemorrhages. Systemic causes include endocarditis; psoriasis; renal, pulmonary, and endocrine disease; and systemic skin conditions ⁴³.

Figure 20. Fingernail Splinter hemorrhages

Ingrown fingernail

Ingrown nail or onychocryptosis,  is a common condition, seen mostly in adolescents and young adults. The cause is multifactorial: repeated trauma, hyperhidrosis (excessive sweating), a broad nail plate, cutting the corners of the nail at an angle ⁴⁴. The condition can be classified into 3 or 4 progressive stages. In stage 1, the lateral nail border is painful and slightly swollen; the later stages are characterized by marked hypertrophy of the lateral nail folds and the development of granulation tissue.

Home remedy for ingrown fingernail

Treating your fingernails gently can help prevent ingrown fingernail. Consider these simple tips:

• Keep your fingernails dry. Repeated or prolonged contact with water can contribute to split fingernails. Wear cotton-lined rubber gloves when washing dishes, cleaning or using harsh chemicals.
• Practice good nail hygiene. Keep your fingernails neatly trimmed, and round the tips in a gentle curve. When you use hand lotion, rub the lotion into your fingernails and cuticles, too. Don’t bite your fingernails or pick at your cuticles.
• Avoid harsh fingernail care products. Limit your use of nail polish remover. When using nail polish remover, opt for an acetone-free formula.
• Apply a protective layer. Applying a nail hardener might help strengthen fingernails.

If your best efforts to preventing ingrown fingernails don’t seem to help, see your doctor or dermatologist for additional suggestions. Some research suggests that the nutritional supplement biotin might help strengthen weak or brittle fingernails.

Treatment depends on the clinical stage: while conservative measures are sufficient in stage 1, surgery is indicated in stages 2 to 4.

In onychocryptosis, the aim of surgery is to eliminate granulation tissue and hypertrophic tissue and to perform a matricectomy. Various clinical studies have shown matricectomy with 88% phenol to be a simple technique that gives excellent results with minimum complications. Several surgical techniques have been described for removing excess soft tissue. The method most often used is the Howard-Dubois technique, which is usually effective in mild to moderate cases.

References

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Ingrown toenail

Toenails and fingernails are clear, hard derivatives of the stratum corneum. They are composed of very thin, dead, scaly cells, densely packed together and filled with parallel fibers of hard keratin. An ingrown toenail or onychocryptosis, occurs when the edge of the nail grows down and into the skin of the toe. There may be pain, redness, and swelling around the nail.

An ingrown toenail may occur at any age and is the mostly commonly encountered toenail problem likely to be seen in general practice ¹.

The epidemiology of ingrown toenail (onychocryptosis) is difficult to determine as it is often considered to be a minor medical problem and as such has been some-what neglected in the literature. The few studies that have been conducted suggest a slightly higher male-to-female ratio, particularly in the 14–25 age group ², but it can affect patients of any age. There are multiple reasons why an ingrown toenail will develop, including improper nail cutting technique, tight-fitting footwear, trauma, anatomical factors such as thickening of the nail plate, pincer-shaped toenail, pressure from abutting digits caused by hallux valgus or lesser toe deformities, the presence of a subungual exostosis and, occasionally, the use of isotretinoin in the treatment of severe acne ³, ⁴, ⁵.

Causes of ingrown toenail

An ingrown toenail can result from a number of things, but poorly fitting shoes and toenails that are not trimmed properly are the most common causes. The skin along the edge of a toenail may become red and infected. The great toe is usually affected, but any toenail can become ingrown.

Ingrown toenails may occur when extra pressure is placed on your toe. Most commonly, this pressure is caused by shoes that are too tight or too loose. If you walk often or participate in athletics, a shoe that is even a little tight can cause this problem. Some deformities of the foot or toes can also place extra pressure on the toe.

Nails that are not trimmed properly can also cause ingrown toenails.

• When your toenails are trimmed too short or the edges are rounded rather than cut straight across, the nail may curl downward and grow into the skin.
• Poor eyesight and physical inability to reach the toe easily, as well as having thick nails, can make improper trimming of the nails more likely.
• Picking or tearing at the corners of the nails can also cause an ingrown toenail.

Some people are born with nails that are curved and tend to grow downward. Others have toenails that are too large for their toes. Stubbing your toe or other injuries can also lead to an ingrown toenail.

Prevention of ingrown toenail

Wear shoes that fit properly. Shoes that you wear every day should have plenty of room around your toes. Shoes that you wear for walking briskly or for running should have plenty of room also, but not be too loose.

When trimming your toenails:

• Considering briefly soaking your foot in warm water to soften the nail.
• Use a clean, sharp nail trimmer.
• Trim toenails straight across the top. Do not taper or round the corners or trim too short.
• Do not pick or tear at the nails.

Keep the feet clean and dry. People with diabetes should have routine foot exams and nail care.

Figure 1. Ingrown toenail

Figure 2. Nail anatomy

How to treat an ingrown toenail

Often the medial or lateral nail edge of an incurved toenail may press into the nail sulcus without actual skin penetration, which leads to the formation of a painful hyperkeratotic lesion. Should the nail plate penetrate through the thin skin of the nail sulcus, infection and hypergranulation tissue will ensue and the toenail is then best described as ingrown (Figure 1) ⁶. Either condition may become symptomatic and require definitive surgical management. Some doctors suggest that, ideally, all presentations of ingrown toenail should be managed conservatively in the first instance ⁷.

Conservative treatment

Careful trimming of the affected distal nail corner is the preferred conservative management of an incurved toenail followed by application of a suitable antiseptic dressing. Referral to a podiatrist to carefully trim the nail edge and debride any hyperkeratotic lesion may be necessary. Traditional conservative treatments have included the use of astringent soaks such as hypertonic solution of Epsom salts or the application of 25% silver nitrate solution may be beneficial but are rarely used today. Encouraging patients to carefully trim their toenails to avoid creating sharp spicules and to place small inserts of cotton wool beneath the nail corners to protect the skin of the nail fold may also be helpful ⁸.

Patients presenting with an ingrown toenail that has penetrated the nail sulcus usually require a partial avulsion of the offending border of toenail to allow for drainage and the excision of any hypergranulation tissue ⁹. Local anesthesia should first be attained via a digital ring block injection of the hallux proximal to the area of erythema with plain local anaesthetic solution. Using small sterile nail nippers, the distal corner section of the involved nail edge is removed taking care not to leave any sharp projections. Care must be exercised not to extend the nail excision more proximal than necessary to avoid the nail matrix area. Hypergranulation tissue should be excised if present. Application of a haemostatic dressing such as Gelatamp may also be necessary. Oral antibiotics are sometimes required but are usually not necessary, providing the offending nail section and any hypergranulation tissue are removed. Home care then consists of soaking twice daily in Epsom salt or saline solution and using a topical antiseptic dressing until healed.

Home remedies for ingrown toenail

• If you have diabetes, nerve damage in the leg or foot, poor blood circulation to your foot, or an infection around the nail, go to the doctor right away. Do NOT try to treat this problem at home.

To treat an ingrown nail at home:

• Soak the foot in warm water 3 to 4 times a day if possible. Keep the toe dry, otherwise.
• Gently massage over the inflamed skin.
• Place a small piece of cotton or dental floss under the nail. Wet the cotton with water or antiseptic.

You may trim the toenail one time, if needed. When trimming your toenails:

• Consider briefly soaking your foot in warm water to soften the nail.
• Use a clean, sharp trimmer.
• Trim toenails straight across the top. Do not taper or round the corners or trim too short. Do not try to cut out the ingrown portion of the nail yourself. This will only make the problem worse.

Consider wearing sandals until the problem has gone away. Over-the-counter medications that are placed over the ingrown toenail may help some with the pain but do not treat the problem.

If this does not work and the ingrown nail gets worse, see your family doctor, a foot specialist (podiatrist) or a skin specialist (dermatologist).

If your ingrown nail does not heal or keeps coming back, your doctor may remove part of the nail.

• Numbing medicine is first injected into the toe.
• Using scissors, your doctor then cuts along the edge of the nail where the skin is growing over. This portion of the nail is then removed. This is called a partial nail avulsion.
• It will take 2 to 4 months for the nail to regrow.

Sometimes your doctor will use a chemical, electrical current, or another small surgical cut to destroy or remove the area from which a new nail may grow.

If the toe is infected, your doctor may prescribe antibiotics.

Ingrown Toenail Surgery – Winograd technique

If conservative care proves unsatisfactory or if the patient presents with a recurrent ingrown toenail then surgical treatment is indicated. Sharp nail resection and phenol-ablation techniques have been reported in the literature as safe and effective methods for treating ingrown toenails ¹⁰, ¹¹, ¹².

The Winograd technique is perhaps the most commonly performed sharp procedure ¹⁰ and is often used when a hypertrophied nailfold is in need of excision. Winograd, a US podiatrist first described the technique in 1929 ¹³. A large case series analysis published by Güler et al ¹⁰ in 2014, which followed 239 patients who underwent a Winograd procedure for ingrown toenails, reported that 96.3% (n = 230) were satisfied with the procedure and 231 patients (96.6%) were satisfied with the cosmetic result ¹⁰. Another recent analysis performed by Kayalar et al ¹¹ of 224 patients who underwent the Winograd procedure found a high success rate of 91.2% (n = 202), with revisional surgery only required in 7.1% 
(n = 16) at a minimum 10-month follow-up ¹¹.

The local anesthetic preferred for the procedure is either bupivacaine 0.5% or ropivacaine 0.75% plain. Instruments and materials required are:

• nonstick antiseptic gauze (eg Bactigras paraffin-wax gauze)
• 4.0 non-absorbable suture
• suture forceps
• scalpel handle
• English anvil nail splitter
• small curette
• straight haemostat
• #15 blade
• sterile saline
• digit tourniquet (eg Tourni-cot ring)

The procedure is illustrated in Figure 3 and outlined below:

• Prepare the toe using alcohol skin wipes and inject 3–4 ml of bupivcaine 0.5% or ropivacaine 0.75% plain as digital ring block.
• Use standard sterile technique after applying a suitable alcoholic chlorhexidine or povidone-iodine liquid solution to prepare the foot.
• Use a digit tourniquet to exsanguinate the toe.
• Use the nail splitter to split 2–3 mm of the affected side of the nail longitudinally (Figure 3A)
• Make two skin incisions:
  + The first is made deeply through the split nail to include the nail bed extending proximally to include the dorsal skin over the nail matrix (Figure 3B)
  + The final incision is to excise the lateral nailfold, connecting the proximal and distal ends of the initial incision (Figure 3C, D).
• Excise the nail section, bed and matrix tissue in total (Figure 3E) and the gently curette to remove any remaining matrix tissue (Figure 3F).
• Flush with normal saline.
• Close the wound with simple interrupted sutures (Figure 3F, H).
• Remove the tourniquet and allow the toe to bleed for a minute or two with local pressure to control the reactive hyperaemia often encountered after release of the tourniquet.
• Dress the toe with a suitable antiseptic dressing, sterile gauze and crepe bandage.

The patient should be advised of the following the post-operative protocol:

• Rest and elevate the foot.
• Use oral analgesics as needed.
• Keep the dressing dry until post-operative review.
• Advise of increasing pain/discomfort (infection).
• The suture will be removed in 5–7 days.

Figure 3. Ingrown Toenail Surgery – Winograd technique

Ingrown Toenail Surgery – Phenol Matrixectomy

Phenol matrixectomy is an alternative procedure often favoured by podiatrists and was first described by Boll, a US podiatrist, in 1945 ¹⁴ and popularised by Bell, a UK podiatrist, in 1977 ¹⁵. The procedure differs from the Winograd technique in that the nail matrix is destroyed via chemical ablation rather than being surgically excised. Phenol BP is caustic to tissues and, although the optimum application time has not been accurately determined, a histological study on fresh cadaveric specimens suggested at least 60 seconds is necessary for the phenol to penetrate matrix tissue ¹⁶. Phenol matrixectomy has been reported to offer certain advantages over the more traditional surgical approach, including lower levels of post-operative pain and infection, and has comparable success rates ¹⁷. A recently published randomised controlled trial of 123 patients with ingrown toenails concluded that the phenolic ablation technique produced less recurrence and spicule formation than the sharps nail resection (n =117 at 12 months follow-up) and no significant difference in post-operative infection rates ¹². Another large retrospective case study of 197 phenolic ablations performed reported a 98.5% (n = 194) success rate at mean follow-up of 36 months with no severe complications observed ¹⁸.

The local anaesthetic preferred for this procedure is lignocaine 1–2% plain. Instruments and materials required are the same as those listed above for the Winograd technique plus:

• Betadine ointment
• Beaver handle with #62 Beaver blade
• sterile cotton-tipped applicators
• liquefied phenol BP.

No sutures are needed. The procedure is illustrated in Figure 4 and outlined below:

• Prepare the toe using alcohol skin wipes and inject 3–4 ml of lignocaine 1–2% plain as digital ring block.
• Use standard sterile technique after preparing the foot.
• Use a digit tourniquet to exsanguinate the toe.
• Use a nail splitter to split 2–3 mm of the affected side of nail longitudinally (Figure 4A) and complete to the proximal edge with the #62 Beaver blade (Figure 4B).
• Perform avulsion of the nail by grasping the sectioned nail with a haemostat and using a gentle distraction technique to rotate it towards the midline of the nail plate and ease the nail free of the nail bed (Figure 4C, D).
• Gently curette the surgical site to remove any remaining matrix tissue.
• Apply liquid phenol BP directly to the site of the germinal nail matrix using small cotton wool applicator tips or the corner of gauze soaked phenol in 3 x 20-second applications (Figure 4E). Application of phenol should be carefully confined to the immediate surgical area, avoiding excess phenol contact with surrounding skin as this may result in unnecessary tissue injury. It is important to ensure that the nail sulcus and matrix area are dried immediately before applying phenol as the chemical is quickly neutralised by body fluid.
• Flush the site using chlorhexidine solution (Figure 4F).
• Remove the tourniquet and use local pressure to control any bleeding, which is normally minimal if any.
• Dress the toe with Betadine ointment, sterile gauze and crepe bandage.

Advise the patient of the following post-operative protocol:

• Postoperative analgesics are rarely required.
• Keep the toe dry overnight.
• Clean the site daily after showering using Epsom salts dissolved in water and to re-dress with Betadine ointment and a simple toe dressing until fully healed (2–3 weeks).
• Monitor for signs of increasing pain/discomfort (infection).
• The wound will be reviewed at 1 week post-operative to evaluate healing, at which time the wound should be debrided of any material inhibiting free drainage of the healing tissue.

Figure 4. Ingrown Toenail Surgery – Phenol-ablation technique

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