Dermatology

Ingrown Nails (Onychocryptosis, Ingrown toenails)

Ingrown Nails (Onychocryptosis)

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Are You Confident of the Diagnosis?

Characteristic findings on physical examination

Diagnosis of ingrown nails (onychocryptosis) is based on the clinical appearance. Most often, the toenails are affected as compared to the fingernails. Overall, the great toenails are most commonly affected. Characteristic clinical history includes pain with pressure on the affected side of the digit, usually with ambulation. Serous drainage can also be noted.

On physical examination, often the lateral aspect (lateral nail fold) of the affected digit is swollen, erythematous, and tender to palpation. It can be possible to directly visualize the responsible nail plate embedded in the surrouding soft tissue of the nail unit. With repeated trauma to the affected nail unit, hemorrhage can occur. Granulation tissue is common at the site of the ingrown nail, and can also be associated wtih hemorrhage. The affected area may become secondarily infected.

Expected results of diagnostic studies

If the offending nail plate is removed and sent for histologic analysis, usually no fungi are identified. If fungi are identified, onychomycosis may be a contributing factor to the ingrown nail and should be treated appropriately.

Diagnosis confirmation

The diagnosis is generally straightforward with a clinical examination. However, one might consider other causes of digital swelling and pain, such as an implated foreign body (history of localized trauma), early cellulitis (erythema, and warmth extending beyond the local area, possibly associated with systemic symptoms), and gout (inflammatory symptoms focused on joints).

Who is at Risk for Developing this Disease?

The most important and common risk factor for developing an ingrown nail is improper routine clipping and trimming of the nails, or tearing of the nail. To prevent ingrown nails, the nail plate should be clipped evenly across. Common improper nail clipping techinques include cutting the nails too short, and with a “V-cut” pattern or a “round cut” pattern. Cutting the nails improperly can cause the nail plate to project into the soft tissue of the nail unit and cause the symptoms of an ingrown nail.

Other habits such as wearing high-heeled shoes, ill-fitting shoes which are too tight, and shoes with a tight toe box can put pressure on the toes and contribute to the development of ingrown nails. Other risk factors for developing ingrown toenails include wide feet, as well as use of some medications, such as systemic retinoids and protease inhibitors. Repetitive trauma, (perhaps from sports), and traumatic injuries can also be a risk factor.

Congenital ingrown nails and ingrown nails in infancy can also occur. Ingrown nails can occur secondary to congenital malalignment of the toenails in children. Overall, ingrown nails are seen more frequently in men, and are more common in adolescents and young adults.

What is the Cause of the Disease?

Etiology

Pathophysiology

While ingrown nails clinically appear to be infected, and secondary infection can occur, the primary pathophysiology is that of a foreign body reaction caused by the ingrown nail itself. The nail plate which becomes implanted in the soft tissue of the nail unit acts as a foreign body, and the subsequent inflammatory reaction is a response to it. From a variety of causes, a spicule of nail may form and be the nidus for the inflammatory reaction.

Systemic Implications and Complications

The systemic implication at needs to be considered is the possibility that a secondary infection can develop from an ingrown nail, and such an infection could spread to other parts of the body (cellulitis). This is especially important to consider in immunocompromised individuals, such as diabetics. It is important to treat an ingrown nail before such adverse systemic sequelae occur.

Treatment Options

A variety of treatment options are possible for ingrown nails, and the approach can be chosen based on the severity of the problem. The main goal of therapy is to remove the inciting implanted nail plate from the soft tissue of the nail unit.

Conservative therapies include putting a cotton wisp or a string of dental floss under the portion of the nail plate which is implanted. These therapies can be combined with cold water soaks mixed with salt or Epsom salts three times per day. After each soak, a mid-potency or high-potency topical steroid can be applied. Examples of topical steroids that can be used include triamcinolone acetoinide ointment 0.1% if the inflammation is mild or moderate, and clobetasol propionate ointment 0.05% if the inflammation is more intense.

A therapeutic maneuver that is gaining popularity is to employ a gutter splint, fashioned from intravenous tubing, which is slid over the area of the nail plate that is implanted. The gutter splint can be fashioned in place with an acrylic adhesive. For additional support to the nail unit, acrylic can also be used to create a prosthetic nail if the remaining nail is short, which not only is helpful aesthetically, but also counteracts upwards force from the nail bed. Taping techniques can also be employed with or without the gutter splint to direct the affected soft tissue away from the embedded nail plate and enhance healing.

Simply removing the lateral nail plate will provide temporary relief of the discomfort from an ingrown nail, but recurrences are common, especially if predisposing factors are not corrected. The combination of a total or partial nail avulsion with phenol therapy reduces the rate of symptomatic recurrence of an ingrown nail. However, there is an increased risk of infection when phenol is used as compared to nail avulsion alone.

If more conservative approaches fail or the ingrown nail is severe, then destruction of the portion of nail matrix at the site of the ingrown nail can be considered. A variety of destructive approaches are possible. The most commonly employed technique is use of a phenol 88% ablation of the nail matrix on the side of the nail that is ingrown (lateral nail matricectomy). After a lateral nail avulsion, the phenol is applied to the corresponding area of nail matrix at the site of the ingrown nail.

One published method of applying the pheol is to use a urethral swab with a cotton tip and metal handle that can be bent. These are sold under the brand name Calgiswab. The phenol is applied to the matrix for 30 seconds, for a total of three times. The surgical area is then cleansed with alcohol or saline. Other chemicals have been used for this purpose, including 10% sodium hydroxide. If granulation tissue is present, it can be removed with a currette.

A study by Bostanci et al that compared a 3-minute application of 88% liquified phenol and a 1-minute application of 10% sodium hydroxide chemical matrixectomies for ingrown toenails showed that sodium hydroxide causes less postoperative morbidity and provides a faster recovery.

Trichloroacetic acid 100% has also been reported to be used for this purpose with good results. Kim et al treated 40 ingrown nail edges with 100% tricholoroacetic acid after parital nail avulsion for chemical matrixectomy. The success rate was 95%, with two nails of one patient demonstrating recurrence. Most of the wounds healed within 2 weeks, and the cosmetic results were good.

An electrode can also be employed to perform electrodesiccation and curettage of the affected nail matrix. A surgical matrixectomy of the affected area of the nail is also possible, but requires more technical acumen to accomplish. Patients should be warned that the surgical approaches to ingrown nails will cause a permanent change in the appearance of the nail unit..

Postoperative pain can generally be controlled with nonprescription analgesics. Antibiotics may be considered before deciding to proceed with a surgical procedure, to treat a secondary infection. Use of concomitant oral antibiotics with a chemical matrixectomy is controversial, and may not be of benefit for routine use. The clinical features of the patient before treatment and observed with postoperative monitoring should guide the decision to use oral antibiotics.

Optimal Therapeutic Approach for this Disease

For cases of ingrown nails that are mild or moderate, conservative therapies as mentioned above are appropriate. More invasive surgical techniques come with a higher risk of complications, such as infection, and permanently alter the nail apparatus, and should be reserved for more severe or recalcitrant cases.

Patient Management

The frequency of follow-up for ingrown nails will depend on the severity of the disorder as well as the type of therapy instituted. Postsurgical patients should be followed as appropriate. Drainage can occur for weeks after the procedure with a nail matrix phenol ablation. Patients with milder cases can be followed less frequently.

With surgical techniques, ingrown nails respond well, and generally do not need additonal therapy after the postsurgical healing phase is completed. Consideration of change of therapy for the more conservative approaches would depend on how the ingrown nail is affecting the patient's quality of life.

Unusual Clinical Scenarios to Consider in Patient Management

An important unusual clinical scenario to be aware of is the presence of a secondary infection associated with an ingrown nail. This possibility should be considered if the pain is severe, or if the ingrown nail is associated with draining pus or a clearly identified abscess.

A secondary infection should be treated first with antibiotics before proceeding with any surgical therapies, to avoid infecting the wound. It is important to take a comprehensive past medical history, and to obtain written informed consent before performing nail unit surgery. In particular, the presence of peripheral vascular disease, collagen vascular disease, diabetes mellitus, as well as bleeding disorders may be contraindications.

The peripheral pulses should be checked to ensure good vascular flow. If such health concerns are identified, the patient may be considered high risk, and additional studies or consultaton with other specialists may be indicated.

A thorough review of the patient's current and recent medications is also important, as ingrown nails have been associated with the use of human immunodeficiency virus protease inhibitors, epidermal growth factor receptor inhibitors, and retinoids (isotretinoin and acitretin). Depending on the underlying health reason for use of such medications, they may not be able to be discontinued.

Standard treatments as discussed above can be employed to treat medication-induced ingrown nails. Aside from the possibility of discontinuing a causative medication, specific recommendations for drug-induced ingrown nails are not recognized.

Figure 1.

Ingrown nail. The lateral nail fold is swollen, erythematous, and has serous crust. (Courtesy of Christopher Miller, MD)

What is the Evidence?

Daniel, CR, Iorizzo, M, Tosti, A, Piraccini, B. " Ingrown toenails". Cutis. vol. 78. 2006. pp. 407-8.

(A focused review on ingrown nails with practical pearls for management.)

Di Chiacchio, N, Belda, W, Di Chiacchio, N. " Nail matrix phenolization for treatment of ingrowing nail: technique report and recurrence rate of 267 surgeries". Dermatol Surg. vol. 36. 2010. pp. 534-7.

(In this article, all 267 nail matrix phenolization procedures were performed by the same dermatologic surgeon, resulting in a recurrence rate of 1.9% with a follow-up peroid that ranged from 6-33 months. This study demonstrates a recurrence rate at is lower than most other comparitive studies. The procedures employed to complete the matrix phenolization are described in detail.)

Woo, S, Kim, I. " Surgical pearl: Nail edge separation with dental floss for ingrown nails". J Am Acad Dermatol. vol. 50. 2004. pp. 939-40.

(This brief report describes the technique of using dental floss to separate an ingrown nail from the underlying soft tissue.)

Bostanci, S, Kocyigit, P, Gurgey, E. "Comparison of phenol and sodium hydroxide chemical matrixectomies for the treatment of ingrowing toenails". Dermatol Surg. vol. 33. 2007. pp. 680-5.

(These authors performed chemical matrixectomies on 154 ingrowing nails from 46 patients with either sodium hydroxide or phenol. Initially, pain was higher in the sodium hydroxide group. The incidence and duration of drainage and peripheral tissue destruction was significantly higher in the phenol group. The mean period for complete recovery was 10.8 days in the sodium hydroxide group and 18.02 days in the phenol group. Overall success rates were both very similar at 95%. The authors concluded that both sodium hydroxide and phenol are effective and give high success rates, but sodium hydroxide has less postoperative morbidity and provides faster recovery.)

Arai, H, Arai, T, Nakajima, H, Haneke, E. " Formable acrylic treatment for ingrowing nail with gutter splint and sculptured nail". Int J Dermatol. vol. 43. 2004. pp. 759-765.

(A comprehensive article that describes improper nail cutting practices and their sequelae, as well as the use of formable acrylic to secure a gutter splint and create a sculptured nail for the treatment of ingrown nails. A total of 541 ingrown nails were treated by a variety of modalities between 1979 and 2002, and acrylic treatment with gutter splint and sculptured nail was found to be vastly superior to other methods, which included adhesive tape-attached gutter splint and other conservative measures.)

Heidelbaugh, J, Lee, H. " Management of the ingrown toenail". Am Fam Physician. vol. 79(4). 2009. pp. 303-8.

(A good review article on the topic of ingrown nails that focuses on therapy.)

Kim, S, Ko, H, Oh, C, Kwon, K, Kim, M. " Trichloroacetic acid matrixectomy In the treatment of ingrowing toenails". Dermatol Surg. vol. 35. 2009. pp. 973-9.

(Treatment of 40 ingrown nail edges in 25 patients was undertaken with 100% tricholoroacetic acid for matricectomy. The wounds healed within 2 weeks and did not have prolonged exudate. Pain was not significant. The success rate was 95%, with recurrence in two nails of one patient. The cosmetic results were good.)
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