Nail avulsion and chemical matricectomy

INTRODUCTION — Nail disorders, particularly ingrown, incurved, pincer, hypertrophic, infected, and painful nails, are common conditions in adults (picture 1A-C) [1]. Although abnormalities of nails can be disfiguring, it is usually pain that brings the patient to the clinician. Most asymptomatic nail disorders affect the toenails, but the fingernails can be affected as well. A variety of relatively simple approaches to nail problems can prevent or alleviate symptoms, and others may correct or cure the underlying problem.

Nail anatomy and common office procedures performed on the nails are described here. The principles of nail biopsy and surgery are discussed separately. Nail disorders and routine treatment of ingrown toenails are also reviewed separately.

●(See "Nail biopsy: Indications and techniques".)

●(See "Principles and overview of nail surgery".)

●(See "Overview of nail disorders".)

●(See "Paronychia".)

●(See "Ingrown nails".)

SURGICAL ANATOMY OF THE NAIL UNIT — The surgical anatomy and blood and nerve supply of the nail apparatus are discussed separately. (See "Principles and overview of nail surgery", section on 'Surgical anatomy of the nail unit'.)

PARING, TRIMMING, AND GRINDING — Toenail paring, trimming, and grinding are commonly performed by clinicians and podiatrists on patients with diabetes or those who have physical limitations that affect their ability to perform routine nail care. Paring and trimming can be performed with regular nail clippers, but heavy-duty English anvil nail nippers are recommended because the slow-growing nails of older patients result in a very thick, tough nail plate, which requires the spring-handled device for satisfactory trimming (picture 2).

Procedure — Over the years, a variety of techniques, including cutting the distal nail square, angling the edges, or creating a "V" in the center, have been advocated. After trying many techniques, the author prefers to customize the shape of the nail trim to its problems, most often shaping the distal edge to the toe shape. The nails are trimmed to leave 2 to 3 mm of free nail plate, then an emery board is used to file down sharp edges that may accidentally catch on stockings and lift the nail plate from the bed.

An ingrown portion of a nail plate deeply embedded into the lateral soft tissue can be removed by placing the tip of the nipper under the "ingrown" edge and cutting it free. This simple procedure can temporarily provide pain relief for several weeks.

Sometimes nails are too thick and too dystrophic (picture 3A-B) for nippers alone; in this case, nail grinders are essential (picture 4). Grinders are drills with specially designed bits that grind and sand down the hyperkeratotic material. Grinding and sanding can eliminate a considerable amount of thick keratin, which often substantially reduces pain by removing the hard, inflexible keratin driving into the underlying soft tissue.

Eye protection and a surgical mask or plastic face shield covering the entire face are advised when paring and grinding nails; bits of nail may fly off when cut, and the powdery nail, often infected with fungal elements, is aerosolized.

Wound care — There is no specific care advised after simple trimming, paring, or grinding, although applying a cream or lotion containing 20 to 25% topical urea daily to the nail plate helps prevent excessive thickening. If, while removing an imbedded portion of nail, the skin is broken by the nail, a topical antibiotic covered with an adhesive bandage and washing of the site daily are appropriate until there is complete healing.

NAIL AVULSION — Nail avulsion is a procedure whereby all or a portion of the nail plate is removed from the nail bed. Avulsions are done for diagnostic and therapeutic purposes. Avulsing the nail plate allows for examination and visualization of lesions in the underlying nail bed and matrix. Most frequently, nail avulsion is done for ingrown and incurved nails. (See "Ingrown nails".)

Nail avulsions are sometimes performed when treating onychomycosis because some clinicians believe that elimination of the infected keratin and topical application of antifungal agents along with systemic therapy enhances therapeutic response, although evidence-based data are lacking [2]. (See "Onychomycosis: Management", section on 'Surgery'.)

Sometimes nails are avulsed traumatically. When there is partial traumatic avulsion, the nail can be trimmed short and covered with an adhesive bandage to prevent "catching" and further traumatic avulsion. An effort should be made to maintain as much of the remaining adherent nail plate as possible so as to prevent further damage to, and keratinization of, the nail bed.

Procedure — Nail avulsion is extremely painful and requires adequate anesthesia for optimal results. The patient should be in a recumbent position. Anesthesia is provided by a wing block (distal digital block) or digital block supplemented with local injections. For simple nail avulsion, the preference of many clinicians is the wing block, as this provides adequate and immediate local anesthesia [3]. (See "Digital nerve block".)

The affected digit should be prepped with povidone-iodine or chlorhexidine solution, or it can be soaked in the antiseptic while waiting for a digital block to take effect. Before starting the procedure, the adequacy of anesthesia should be tested by inserting a needle into the digital tip and under the nail.

To begin, the operator holds the digit to keep it stable during the procedure. A blunt instrument, such as a narrow dental spatula, a thin, small elevator (Freer septum elevator) (picture 5), or a straight mosquito hemostat, is then placed under the distal edge of the plate (picture 6). Advance the instrument longitudinally toward the matrix in the natural cleavage plane. Some force is initially required to advance the instrument, but then it becomes relatively easy to advance until the bottom of the "cul-de-sac" is reached. When performing a complete avulsion, the maneuver is repeated by inserting and advancing the spatula or elevator under an adjacent section of nail plate until the entire plate is freed from underlying nail bed and adjacent nail folds. The same instrument is then placed on top of the nail plate under the lateral and proximal nail folds to break these attachments. The free distal edge of the nail is then grasped with a hemostat and pulled out with a side-to-side or twisting motion. Any strands of epithelium can be snipped with small scissors [4-6].

With partial avulsions, the instrument is advanced as before under the nail plate longitudinally until the nail groove is reached; however, the separation of the nail plate from the nail bed is confined to the width of the plate that needs to be removed. After this is accomplished, the surface nail attachments at the lateral fold are lysed as before. A nail splitter (picture 7) is placed under the plate, advanced the entire length of the plate, and then closed to cut the nail (picture 8). The free edge of the avulsed portion of nail is then grasped with a hemostat and pulled out. If exuberant granulation tissue is present in the nail fold, it can be debrided with a sharp curette.

Bleeding is usually minimal if only avulsion is performed; however, there may be bleeding in the nail fold if granulation tissue was removed. Bleeding can be stanched by applying aluminum chloride 35% with a cotton-tipped applicator. Having removed the nail, a thin film of petrolatum or antimicrobial ointment is placed on the exposed nail bed and adjacent nail fold and then covered with a small, nonadherent dressing. The entire digit is then wrapped securely, but not too tightly, with 1 or 2 inch rolled gauze.

Patients should be advised to have someone accompany them for the procedure and to bring an open-toed shoe or slipper to wear home after the procedure.

Elevation of the extremity for two to three postoperative hours helps minimize discomfort as the anesthetic wears off. The pain following simple avulsion is variable but can usually be managed with elevation and acetaminophen or ibuprofen. Local swelling, pre-existing inflammation, and tight dressings are contributing factors to pain. Intermittent elevation of the extremity over the next 48 to 72 hours can help reduce swelling and pain.

Wound care — After simple avulsion, the digit should be soaked in warm water 24 to 48 hours after the procedure. Before removal of the dressing, patients are instructed to soak their digit in the shower or in a bowl to avoid bleeding and pain when the dressing is removed. A gelatinous film of epithelium may be present over the exposed nail bed and can be gently removed with dilute hydrogen peroxide on a cotton-tipped applicator. The cotton tip should be rolled over the site gently, avoiding rubbing or vigorous attempts at tissue removal. A small amount of petrolatum or antibiotic ointment is placed on the tissue, and then it is covered with an adhesive bandage for a simple avulsion or roller gauze if the nail fold was debrided or if a matricectomy was performed. This dressing change should be repeated daily.

The nail bed typically epithelializes within 7 to 10 days.

CHEMICAL MATRICECTOMY

Overview — Chemical matricectomy is the chemical ablation of all or part of the nail matrix with phenol, sodium hydroxide, or trichloroacetic acid (TCA). We typically use phenol. The rationale for chemical matricectomy is to destroy the matrix to prevent the nail from growing. Typical indications are recurrent or chronically ingrown or incurved nails with frequent pain or infection. (See "Ingrown nails".)

Chemical ablation has several advantages over surgical matricectomy. It is relatively easy to perform, causes minimal bleeding, allows the patient to return to normal activities after a few days, and is not significantly disfiguring.

Data on recurrence rates after chemical matricectomy derived from observational studies vary from less than 5 to 18 percent [7-9]. A 2012 systematic review and meta-analysis including 24 randomized trials (2826 patients) evaluating interventions for ingrown toenails concluded that nail avulsion combined with phenol destruction of the nail matrix leads to a 75 to 91 percent reduction in the recurrence of ingrowing toenails compared with excisional techniques alone [10]. The risk of postoperative secondary infections is also reduced [7].

The procedure below describes the use of phenol in performing the chemical matricectomy. Studies have reported low recurrence rates with the use of sodium hydroxide [11], TCA [12,13], or bichloracetic acid [14]. However, only a few studies have directly compared the efficacy and postoperative morbidity of these agents:

●One study comparing sodium hydroxide and phenol in 46 patients reported a similar success rate (95 and 96 percent, respectively) after a median follow-up time of 19 months. However, the duration of postoperative oozing and time to complete recovery were shorter in the sodium hydroxide group than in the phenol group [15].

●Another study comparing the efficacy and postoperative morbidity of phenol and TCA in 96 nails from 80 patients found a similar efficacy (100 percent) for both agents at four months. However, postoperative oozing at four weeks was observed in a smaller proportion of patients in the phenol group than in the TCA group (9 versus 39 percent) [16].

In the absence of high-quality studies demonstrating one agent to be clearly superior in efficacy, safety, and ease of use, we continue to use phenol.

Procedure — We describe here the procedure for performing chemical matricectomy with phenol. Supplies needed for chemical matricectomy include a preoperative antiseptic solution, anesthesia supplies (lidocaine 2% with or without epinephrine and bupivacaine), sterile drapes, sterile gloves, elevating instrument (dental spatula, Freer elevator (picture 5), straight mosquito forceps), nail splitter (picture 7) (for partial matricectomy), scissors, forceps, small curette (an ear curette or other 1 to 2 mm curette), tourniquet, cotton-tipped applicators, petroleum jelly, fully saturated (88 percent) liquefied phenol, isopropyl alcohol in 20 mL syringes, petrolatum or antibiotic ointment, nonadherent gauze, and roller gauze.

To perform the procedure, the digit must be well anesthetized with a wing or digital block and soaked in the antiseptic solution (see "Digital nerve block"). Place the patient in a recumbent position on the operating table and apply sterile drapes to expose the operative site. The nail plate is partially avulsed if just a portion of the matrix is to be ablated or completely avulsed if the entire matrix is to be ablated. (See 'Nail avulsion' above.)

Any exuberant tissue (ie, granulation tissue) should be curetted or excised with scissors and forceps. Granulation tissue is a highly vascular tissue reaction to the ingrowing nail acting as a foreign body. Once this tissue is removed, bleeding usually subsides. Whether the area of the matrix to be treated should be curetted before the phenol application is controversial [17,18].

The overlying proximal nail fold, adjacent nail bed, and lateral nail folds are then coated with petroleum jelly to prevent phenol from damaging these tissues. A tourniquet is then placed at the base of the digit to ensure hemostasis and the treatment field wiped dry. Blood or any moisture in the treatment area dilutes the phenol, reducing or eliminating the effectiveness of the phenol. Many phenol treatment failures are thought to be due to this, especially among inexperienced operators.

Cotton-tipped applicators are stripped of all but a small wisp of cotton or, alternatively, the bare end of the stick is covered with a small wisp of cotton, which is then saturated with phenol solution. The cotton wisp should be held against the inside mouth of the phenol bottle to drain the excess phenol to prevent dripping. The phenol-soaked wisp is then applied to the matrix and vigorously rubbed into the treatment area for 60 seconds, with particular attention to the lateral horn of the matrix. One to three subsequent, vigorous phenol applications of 60 seconds can be made in a similar fashion.

The tissue will denature quickly and turn white or gray. The denaturation by phenol is self-limiting, and no irrigation is necessary; however, some surgeons irrigate the treated area with 30 to 50 mL of isopropyl alcohol or water. The tourniquet is then removed [19]. The tourniquet should never be left in place for longer than 10 to 15 minutes.

There is no consensus among experts on the application time, with some recommending no less than one minute and others recommending up to four minutes of phenol application [18,20,21]. In one series of 267 nail matrix phenolization procedures with an application time of two minutes, the recurrence rate was 1.9 percent [18]. In another study of 622 procedures, a four-minute application of phenol was associated with a very low rate of subsequent nail regrowth (1 percent) [20]. However, longer phenolization time may be associated with increased postoperative edema and drainage.

After completing a chemical destruction, some clinicians inject a long-acting anesthetic (bupivacaine) 0.6 mL with or without dexamethasone 0.4 mL into the proximal nail fold (total volume of injection is approximately 0.5 mL or less) in each wing [22]. The anesthetic provides an extended period of comfort, allowing the patient to get supplies for postoperative care, get home, and elevate the treated foot or hand. The author has found that patients require less pain medication, few, if any, opioids, and are able to walk comfortably more quickly when using this technique.

Petrolatum or an antibiotic ointment is placed on the nail bed, the site is covered with a nonadherent dressing, and then the entire digit is wrapped with 1 or 2 inch roller gauze. The wrapping should be secure but not so tight as to be uncomfortable. Dressings wrapped too tightly may increase postoperative pain.

The patient is then advised to go home and elevate the affected foot or hand for 24 to 48 hours. We advise patients to apply a cold pack to the dorsal foot (multiple 10- to 15-minute applications) in the first 24 hours to minimize discomfort.

Wound care — The wound care for chemical matricectomy is the same as that for simple avulsion (see 'Wound care' above). Patients should be advised that a serous discharge from the wound may occur in the first few days and up to two weeks postoperatively.

After a partial matricectomy, the affected nail bed begins to keratinize or harden, producing a "pseudonail," and the lateral nail fold epithelium grows toward the remaining nail plate, eventually producing a normal-appearing nail, albeit slightly narrower. With complete matricectomy, the nail bed keratinizes and forms a pseudonail that has the shape of a normal nail plate. Gauze coverings should be used postmatricectomy for one week, then adhesive bandages should be used for an additional two to three weeks.

Occasionally, chemical matricectomy does not completely prevent nail plate regrowth, which is likely due to bleeding that dilutes phenol during the procedure or incomplete destruction of the matrix lateral horn. If a portion of the nail or the entire nail regrows, the procedure can be repeated. Occasionally, a narrow spicule of nail regrows and can be removed using a hemostat. If recurrent and symptomatic, treating the matrix in the area of spicule growth using electrocautery or chemical cauterization can be done.

COMPLICATIONS

Pain — Pain is the most common complication following nail surgery. However, phenolization is usually associated with less discomfort in the postoperative period compared with surgery, which may be due to demyelination of terminal nerve endings for several weeks induced by phenol, resulting in a local anesthetic effect [23]. Most pain occurs in the first 24 to 48 hours, and the majority of patients can return to normal activities while wearing an open-toed shoe after 48 hours. Pain control measures include elevation of the affected limb, use of ice packs, and oral analgesics:

●Adequate elevation requires that the limb be held above the level of the heart. Elevation should be continued for 24 to 48 hours.

●Ice packs applied to the dorsal foot in the case of toenails or dorsal hand or wrist for fingernails may diminish pain and slow the clearing of anesthesia.

●Oral analgesics, including acetaminophen and nonsteroidal anti-inflammatory drugs. (See "Nonopioid pharmacotherapy for acute pain in adults".)

Persistent or worsening pain 48 hours after the procedure suggests an infection [24]. Patients should be instructed to contact the clinician in the following situations:

●The pain worsens rather than improves over 24 hours.

●There is increased swelling.

●There is increasing redness of the area.

●A red streak develops.

●Pus is present.

●There is fever.

Other causes of postoperative pain include dressings that are too tight and pressure from shoes. In both cases, removal is diagnostic and therapeutic; pain is alleviated once the wrap dressing or shoe is removed. This complication can be avoided if patients use adhesive bandages after the initial office-applied dressing is removed and adhere to instructions to avoid closed-toed shoes for a week.

Infection — Antibiotic prophylaxis is not recommended before surgery. Local inflammation, tissue swelling and bleeding, and drainage around the nail are due to the nail embedded in the adjacent soft tissue. Like other foreign body reactions, removing the embedded nail resolves the problem.

Secondary infection is more likely to occur when infection is present before the procedure. Thus, permanent procedures should be avoided in the presence of infection, and infection should be treated prior to operating whenever possible.

If secondary infection is suspected, a culture from the wound should be obtained. Since in the first few postoperative days bacterial infections are in most cases caused by Staphylococcus aureus, empiric therapy for methicillin-susceptible S. aureus should be initiated pending the culture and sensitivity results. Cephalexin is a common option for oral therapy. (See "Acute cellulitis and erysipelas in adults: Treatment".)

Periostitis — An inflammatory reaction of the periosteum has been reported following phenolization of the matrix [25]. It may be due to infection, most often S. aureus, or to procedural or chemical trauma. Symptoms are pain and swelling of the digit, which may extend to the foot. Purulent drainage may be present with infection, and uncommonly, there may be systemic symptoms (eg, fever, chills). Culture of drainage, complete blood count, and radiograph or magnetic resonance imaging of the foot can help rule out infection and osteomyelitis.

Chemical (phenol) burn — Chemical burns can occur when phenol comes into contact with unprotected skin denaturing the healthy tissue. This can be avoided by covering skin adjacent to treatment areas with petrolatum and ensuring the cotton wisp for phenol application does not drip. If phenol touches the skin, flush the area liberally with alcohol, apply petrolatum and cover with a nonadherent dressing, and follow standard superficial burn care management. Clean and dress the area daily using standard superficial burn care. Cellulitis can occur if the injury is not treated and becomes infected.

CONTRAINDICATIONS — Diminished vascular supply to the digit is a relative but not absolute contraindication to nail surgery. It is common for patients with significant peripheral vascular disease, including diabetes, to have painful disorders of the nail, and surgical intervention may be indicated. Avoiding epinephrine in the anesthetic, using digital rather than local blocks (avoid ring blocks), minimizing the duration of a tourniquet application, or using palliative rather than permanent procedures help reduce risk in these patients. Though smoking is not a contraindication to nail surgery, caution should be used in smokers who are at greater risk for infection and for delayed healing [26].

Overt bacterial infection of the operative site is a relative contraindication to chemical matricectomy, and temporizing procedures often need to be performed. Patients with acute infection at the operative site should be treated with a systemic antibiotic for two to three weeks prior to surgery.

SUMMARY AND RECOMMENDATIONS

●Nail avulsion – Nail avulsion is a procedure whereby all or a portion of the nail plate is removed from the nail bed (picture 8). Nail avulsion is extremely painful and requires adequate anesthesia by digital or wing block. Avulsion is done for diagnostic and therapeutic purposes, most frequently for ingrown and incurved nails. (See 'Nail avulsion' above and "Digital nerve block".)

●Chemical matricectomy – Chemical matricectomy is the chemical destruction of all or part of the nail matrix. Typical indications are recurrent or chronically ingrown or incurved nails with frequent pain or infection. After complete or partial nail avulsion, phenol is applied to the matrix portion to be treated. (See 'Chemical matricectomy' above.)

●Complications – Pain and infection are the most common complications following nail surgery. Pain may be controlled by elevation of the affected foot or hand for 24 to 48 hours, application of ice packs to the dorsal foot or hand, and oral analgesics. If infection is suspected, a culture from the wound should be obtained and empiric therapy for methicillin-susceptible Staphylococcus aureus should be initiated pending the culture and sensitivity results. (See 'Pain' above and 'Infection' above.)

●Contraindications – Nail avulsion may be contraindicated in patients with peripheral vascular disease and reduced vascular supply to the digits. When the procedure is necessary, avoid epinephrine in the anesthetic, use digital (but not ring digital blocks) rather than local blocks, and minimize the duration of tourniquet application. (See 'Contraindications' above.)