Most ingrown nail infections are a simple foreign body reaction and resemble the response that the skin has to a splinter or a piece of glass. As the nail irritates the skin adjacent to the nail (periungual folds), it causes a low grade foreign body reaction and soft tissue infection.

The most common reason we develop ingrown nails is due to improper trimming of the nail. The nail is very weak when twisted (torsion). If the nail is trimmed so that a small spur, called a spicule, is left on the border of the nail, the nail will continue to grow forcing the spicule into the skin. As the skin responds to this 'foreign object' it becomes inflamed and sore. The area adjacent to the nail will become increasingly more difficult to trim, and so begins the vicious cycle that is the start of an ingrown nail.

The majority of ingrown nails are on the hallux (big toe). Pain is usually tolerable until the nail is bumped or stepped on. Ingrown nails are extremely common in adolescent boys and in women 2-3 months postpartum. Why? Young boys seem to have little regard for regular hygiene and pregnant women have a difficult time reaching their feet during the last several months of their pregnancy, not to mention the additional burden of their feet swelling.

The shape of the nail can also be a contributing factor for ingrown nails. Pincer nails( as shown to the left), a term used for nails that have a pinched appearance, put pressure on the periungual folds. As shoe pressure is exerted on the nail, the edges of the nail push into the skin just as the weight of something put on a table pushes through the legs of the table to the floor.

Other contributing factors that may cause ingrown nails include trauma to the nail, pressure from adjacent toes and the shape or profile of the forefoot in relationship to the shape of the toe box of the shoe. Medical conditions, such as fungal infections or psoriasis, can change the shape of the nail and contribute to ingrown nails.

Ingrown toenails are treated much the same as a splinter. Antibiotics and soaking can help to reduce the inflammation associated with the ingrown nail, but until the foreign object (ingrown nail) is removed, the stale mate between the nail and adjacent skin will continue. Removal of the offending border of nail is necessary in most cases of ingrown nails.

Many have suggested the 'proper' way to trim the nail, but in actuality, every nail is a bit different from the next nail. Therefore, it's most important to trim the nail in a way that it is not going to irritate the periungual fold. Trimming the nail straight across may work for some but is ineffective for others. Some advocate cutting a groove or V in the distal tip of the nail. This is also ineffective. Cotton under the edge of the nail has been tried, even metallic clips that 'lift' the nail, but each of these will fail in time unless the offending border of the nail is removed. A new product called NailEase will help lift the edges of the nail in a limited number of cases. Many pregnant women develop ingrown nails due to their inability to reach their feet. NailEase is a great product for them since they are poor surgical candidates until they deliver.

The technique used most commonly today to treat infected ingrown nails is called a phenol-alcohol procedure (P&A procedure). This procedure is performed in the office under a local anesthetic on an out-patient basis. After the toe is numbed and cleaned with a disinfecting agent, a thin margin of nail is removed. Phenol, which is 77% carboxylic acid, is applied to the nail matrix to kill the cells that produce that small margin of nail only. The phenol is then flushed out with alcohol. Patients can return to a Band-Aid and regular shoes the next day.

The interesting thing about the phenol-alcohol procedure is the lack of pain experienced by patients following their surgery. This is due to the fact that phenol has a topical anesthetic property that last for 2-3 weeks. Although the procedure will drain for several days, the benefit of using phenol is significant. Phenol is best know as the active ingredient in Chloroseptic Mouthwash Spray. In Chloroseptic, phenol is used in a more dilute concentration but has the same effect in that it inhibits sore throat pain.

Other surgical procedures may be used with or without phenol and include the use of a CO2 laser or other chemicals to destroy the matrix cells. The decision to remove one border, both borders or the entire nail should be discussed with your doctor.

The following images show the steps involved in correcting an ingrown nail with a P&A or phenol alcohol procedure.  Image 1 shows administration of local anesthesia.  Once the nail has been anesthetised, the foot is prepped with a Betadine or comparable  solution.  Image 2 shows a small tourniquet (Penrose drain) around the toe to inhibit bleeding (hemostasis).  A nail splitter is being used to create a clean split to remove just the borders of the nail.  Image 3 shows a hemostat being used to remove the nail.  The nail bed is then scraped with a small curette to physically destroy the nail matrix.  In image 4 we see the application of phenol.  Phenol application is normally done 3 times for 5-10 seconds each application.  And image 5 shows the final bandage.  This procedure is completed in 10 minutes and is performed in an office setting.  Post-op care varies, but steps are taken to promote drainage of the nail and may include Epsom Salt soaks or application of steroid/antibiotic drops.  Patients return to a normal shoe the day after surgery wearing just a 1 inch Band-Aid.  Healing takes 10-14 days. 

Beau's lines - deep longitudinal grooves in the nail plate

Eponychium - thin layer of skin overlying the matrix at the base of the nail

Koilonychia - spoon shaped nails

Lunula - a small white moon shaped area at the base of the nail. The purpose of the lunula is not clear but it appears to be an extension of the nail matrix.

Matrix - the cells beneath the eponychium that produce the nail

Onychocryptosis - onycho is derived from Greek and refers to any nail condition. Crypt, or to bury is combined to form a word that describes an ingrown nail where the nail is buried in the nail fold. This term can be used to describe an ingrown nail both with or without an infection.

Onychomycosis - a fungal nail infection

Paronychia - para refers to parallel. Onychia is derived from Greek and refers to nail. Paronychia is a condition that present with pain along the entire border (parallel to) of the nail. This term is often used to describe chronic pain at the edge of the nail with or without an infection. This term is also used to describe irritation form the nail at the base of the nail.

Pincer nails - nails that are pinched

Splinter hemorrhages - small bruises beneath the nail plate. Common to endobacterial carditis or atrial fibrillation.

Subungual - beneath the nail

Subungual exostosis - a bone spur beneath the nail

Subungual hematoma - dark discoloration of the nail due to bruising beneath the nail

Ungual - refers to nail

Nail is an elastic, transparent layer of keratin. It is surrounded on two sides by soft skin referred to as the periungual folds. The base of the nail is called the eponychium and the distal tip of the nail is called the hyponychium. Nail cells are created in a small envelope called the nail matrix.

No information is available for this topic.

The symptoms of an ingrown nail can vary. Pain can be chronic due to a low grade mechanical irritation of the periungual folds or be acute due to a foreign body reaction and infection by the skin adjacent to the nail. When the skin adjacent to the nail perceives the nail to be a foreign object, it will mount a response to push out the nail, just as the skin would respond to a splinter. This response is usually a low grade infection.

The differential diagnosis for this condition should include;

Abscess

Blister

Benign soft tissue tumor
Glomus tumor
Chondroma
Fibroma
Inclusion cyst

Bone spur

Lister corn or callus

Gout

Malignant soft tissue tumor
Malignant melanoma
Kaposi's Sarcoma

Psoriatic arthritis

Ulcer

Verrucae

Wart

• Onychomycosis

• Toe Nail Fungus

• Toe Nail Injuries

• Toe Nail Trimming

• Lister Corn

This article was written by Jeffrey A. Oster, DPM and last updated 6/12/07. No additional information is available for this topic.