Principles and overview of nail surgery

INTRODUCTION — Nail surgery is performed to remove benign and malignant nail tumors, alleviate pain secondary to ingrown and traumatized nails, and diagnose clinically ambiguous lesions and dystrophies [1,2]. Because of the propensity for scarring and inadequate sampling, nail surgery is best performed by clinicians with appropriate training and experience. Prerequisites for a successful nail biopsy include a thorough understanding of nail anatomy, adequate anesthesia and hemostasis, and proper patient selection and preparation. Nail avulsions, biopsies, and excisions can be safely performed in the office setting [2].

This topic will discuss the surgical anatomy of the nail apparatus, preoperative patient evaluation, anesthesia techniques, basic surgical procedures, and surgical treatment of specific nail lesions.

Nail disorders, nail biopsy techniques, nail plate avulsion, and chemical matricectomy are discussed separately. (See "Overview of nail disorders" and "Nail biopsy: Indications and techniques" and "Nail avulsion and chemical matricectomy", section on 'Nail avulsion' and "Nail avulsion and chemical matricectomy", section on 'Chemical matricectomy'.)

SURGICAL ANATOMY OF THE NAIL UNIT — The nail unit is composed of the nail matrix, the nail bed, the proximal and lateral nail folds, and the hyponychium (picture 1 and figure 1A-C) [1,3].

The nail matrix is the germinative epithelium from which nail matrix keratinocytes differentiate to ultimately form the nail plate [1,3,4]. Although most of the nail matrix is hidden beneath the proximal nail fold, the distal third of the nail matrix is sometimes visible through the proximal portion of the nail plate as a half-moon shaped structure called the lunula [1,3,4]. The proximal nail matrix forms the dorsal (superior) portion of the nail plate whereas the distal nail matrix forms the ventral (inferior) surface of the nail (figure 2) [1,3-5]. The proximal portion of the nail matrix is responsible for the production of approximately 80 percent of the nail plate, allowing the nail plate to achieve a natural convex curvature as it grows distally [4,5].

The nail bed extends transversely between the lateral nail folds and longitudinally from the distal lunula to the hyponychium [1,3,4]. The nail bed possesses a rich vascular supply that results in the pink color visible through the tightly adherent and translucent nail plate. The epithelial cells of the nail bed contribute to the undersurface of the nail plate forming a tight seal (figure 2) [1]. For this reason, nail bed surgery is sometimes complicated by mild onycholysis and rarely by permanent nail dystrophy.

The dermoepithelial interface of the nail bed is composed of longitudinal rete ridges and papillary body ridges. Each papillary body ridge contains three to five longitudinally oriented capillaries, explaining the longitudinal orientation of splinter hemorrhages [1,3,4]. No subcutaneous tissue separates the dermis of the nail bed from the periosteum of the distal phalanx.

The proximal and lateral nail folds are collectively known as the paronychium [1,3]. The nail folds serve to protect the nail plate and direct its growth in the correct orientation. The lateral nail folds of the toes are often very pronounced, making patients susceptible to the development of ingrown nails [4]. The skin of the dorsal aspect of the proximal nail fold has a thin dermis; it lacks hair follicles and sebaceous glands, but contains some sweat glands in its most proximal part [6]. The ventral surface of the proximal nail fold, also called the eponychium, is thin and lacks all skin appendages. The stratum corneum of the tip and ventral surface of the proximal nail fold extends onto the nail plate as the cuticle, which protects the proximal nail plate from environmental pathogens and irritants. During nail surgery, it is important to remember that the insertion of the extensor tendon of the digit is located approximately 12 mm proximal to the cuticle [1]. Although the tendon is usually proximal to the nail surgical field, it may be compromised in extensive nail surgery.

The hyponychium, located at the distal free edge of the nail plate just proximal to the distal groove, is contiguous with the volar skin and functions to seal and protect the distal nail unit from the environment. Disruption of the hyponychium may result in onycholysis and subsequent bacterial invasion [1,3]. The paronychium plus the hyponychium and nail bed is called the perionychium.

The distal phalanx possesses a rich blood supply. Two proper digital arteries, the smaller dorsal and larger volar arteries, run alongside each digit and anastomose approximately at the level of the distal interphalangeal joint to form arcades at the levels of the proximal nail fold and the nail bed [3]. Capillaries that arise from these vessels run obliquely in the proximal nail fold and nail matrix and parallel to the surface of the longitudinally oriented papillary ridges of the nail bed. Distal phalanx circulation is complemented by glomus bodies connected to the small muscular arterioles. At lower temperatures, glomus bodies dilate and supply warm blood to the digital capillaries.

The venous system of the digit is more variable. The blood is collected into deep and superficial systems that drain into larger veins that run subcutaneously on the dorsal and volar aspect of the digits.

Paired palmar and plantar nerves run alongside the proper digital arteries and the flexor tendon sheath (figure 3A-B) [1,4,7]. The nails of the second through fourth fingers are innervated by the volar proper digital nerves, whereas the first and fifth nails and all digit tips are innervated primarily by the dorsal digital nerves (figure 4A-B) [3]. Just distal to the distal interphalangeal joint, the digital nerves divide into three main branches, one innervating the nail bed, one the digit tip, and the other the pulp [3,4].

PREOPERATIVE EVALUATION AND PREPARATION

History and physical examination — A complete history and targeted physical examination are necessary before nail surgery. The history should focus on potential causes of neurovascular compromise, altered hemostasis, cardiovascular disease, and the use of drugs that could interfere with anesthesia or coagulation (table 1) [1,2].

Patients should also be questioned about history of allergy to latex, antibiotics, and topical anesthetics such as lidocaine, bupivacaine, ropivacaine, or parabens (a preservative commonly found in anesthetics) [1,2].

Physical examination should include palpation of peripheral pulses, evaluation of fingernails and toenails, and inspection of skin, mucous membranes, hair, and scalp, looking for signs of neurovascular compromise or evidence of associated conditions (eg, systemic sclerosis) [1].

Ancillary tests — When infection is suspected, appropriate mycology, bacteriology, or virology studies should be performed. If a space-occupying lesion or any underlying bony defect is suspected, radiographic studies should be obtained before nail surgery. Clinical photographs of the preoperative nail are recommended for baseline comparison.

Informed consent — Patients should be fully informed of the procedure, alternatives, and risks. The discussion must mention the possibility of inconclusive diagnosis, time needed for nail regrowth, and potential risks of permanent nail dystrophy, bleeding, pain, and infection.

Antibiotic prophylaxis — Prophylactic antibiotics are generally not necessary. However, antibiotic prophylaxis is indicated in the following situations [8]:

●Procedures performed on the lower extremities

●Procedures that are at increased risk of postoperative infection (eg, excisions of mucous cysts that drain preoperatively or procedures involving the bone)

●If the surgical site is infected before the procedure

●If there is an increased risk of methicillin-resistant Staphylococcus aureus (MRSA) infection (see "Methicillin-resistant Staphylococcus aureus (MRSA) in adults: Treatment of bacteremia")

Recommended antibiotic regimens for dermatologic surgery are illustrated in the table (table 2).

Premedication — Nail surgery can be an anxiety provoking experience and premedication may be required in some patients. Preoperative anxiolytic medication with short-acting agents is preferred (table 3) [2]. As an example, hydroxyzine 25 mg taken orally the night before surgery and lorazepam 1 to 2 mg sublingually one hour before the operation are generally effective [9,10]. Some surgeons prefer midazolam for its short-acting hypnotic, retrograde amnestic and anxiolytic properties [2,9]. (See "Procedural sedation in adults in the emergency department: Medication selection, dosing, and discharge criteria", section on 'Benzodiazepines (midazolam, others)'.)

Surgical field preparation — Immediately before a nail procedure the surgical field that includes the relevant digit should be washed with a surgical soap, such as povidone-iodine or 0.5% chlorhexidine-alcohol preparation, and draped in conventional fashion to create a sterile field [1,2]. A sterile glove placed on the hand also may provide a sterile field.

INSTRUMENTS — In addition to standard surgical instruments used for routine cutaneous procedures, nail surgery may require special instruments (picture 2) [1]:

●The Freer septum elevator has thin curved blades that facilitate nail avulsion.

●The English nail splitter is composed of a cutting blade opposed to a flat anvil-like surface and aids partial longitudinal nail avulsion.

●Double-action nail nippers are used for excising thickened nail plates.

●A bone rongeur may be needed for removing bone tumors and trimming thickened toenails [11].

Standard instruments used in nail surgery include hemostats, surgical blades, blade holders, iris- or Gradle-type scissors, needle holders, suture-cutting scissors, excavator-type curettes, skin hooks, and suture [11]. Forceps are not recommended for handling surgical specimens because of their potential for causing crush artifacts [12].

For digital anesthesia, Luer lock syringes or dental syringes with needles tightly secured through the screw-on system are usually needed because the nail and dorsal aspect of the digit is highly resistant to tissue dilation [10,13].

ANESTHESIA

Anesthetic agents — The administration of lidocaine 1 to 2% with or without epinephrine 1:100,000 is safe in most patients undergoing nail surgery [13-18]. Advantages of epinephrine include local vasoconstriction, reduced bleeding, and prolonged duration of anesthesia; however, epinephrine may not be necessary when tourniquet hemostasis is adequate. Epinephrine should be avoided in patients with peripheral vascular disease who are at increased risk for digital ischemia or infarction. (See "Digital nerve block", section on 'Use of epinephrine'.)

One-half to 1 mL of bupivacaine 0.5% is often administered after or in place of lidocaine to provide longer-lasting pain relief (ie, up to eight hours). (See "Subcutaneous infiltration of local anesthetics", section on 'Choice of anesthetic'.)

Ropivacaine in a concentration of 5 mg/mL or less is preferred over lidocaine and bupivacaine by many nail surgeons because it has the same quick onset of action as lidocaine, produces vasoconstriction, provides up to nine hours of postoperative pain relief, and is less cardiotoxic than bupivacaine [13,19-21].

Reduction of injection pain — Thin needles cause less pain on injection, allow slow anesthetic flow, and gradual tissue swelling [10,13]. Thirty-gauge (30 G) needles are recommended for anesthetizing fingers, 27 G for toes, and 30 G for children in all cases [10,13].

Additional measures to reduce the discomfort associated with the needle puncture include [13,22-26] (see "Subcutaneous infiltration of local anesthetics", section on 'Methods to decrease injection pain'):

●Application of eutectic mixture of local anesthetics (EMLA) cream under occlusion for one hour before injection

●Application of topical cryogen spray, ice packs, or vibration

●Alkalinization of acidic lidocaine by adding one part of 1 mEq/mL of sodium bicarbonate to 9 or 10 parts of 1% lidocaine or lidocaine with epinephrine (see "Subcutaneous infiltration of local anesthetics", section on 'Anatomy and physiology')

●Warming the anesthetic to 37°C

Procedure — Luer lock syringes or dental syringes with needles tightly secured through the screw-on system are usually used for anesthetizing the nail unit, since this site is highly resistant to tissue dilation [10,13].

Anesthesia can be administered by digital nerve block or wing block procedure [27]. Most nail surgeons prefer the wing block because it is less painful, requires a smaller amount of anesthetic, and is more rapid than the digital nerve block [13]. The digital nerve block procedures are discussed in detail separately. (See "Digital nerve block", section on 'Digital block procedures'.)

Anesthesia administered by wing block acts immediately [13]. The injection site is a point approximately 5 to 8 mm proximal and lateral to the junction of the proximal nail fold and the lateral nail fold. The needle is introduced at a 45° angle and directed distally to the bone (picture 3A-B) [13]. Approximately 0.5 mL of anesthetic is needed for each side of the digit to distend and blanch the nail folds and anesthetize the three branches of the dorsal nerve. Sometimes blanching of the lateral part of the lunula is noted.

Increased resistance to injection may suggest that the needle has penetrated the periosteum. In this case, careful withdrawal of the needle should result in free flow. To ensure complete anesthesia, the anesthetic must also be injected into the lateral nail fold. The needle may be bent at 120°, reinserted at the initial injection site, and pushed distally to the end of the lateral nail fold. The anesthetic is injected in a retrograde fashion, while pulling the needle back. For complex nail procedures, the ventral nerve branches should also be anesthetized by inserting the needle at the initial puncture site on each side and injecting 0.5 mL of anesthetic into the digit pulp. Following complete anesthesia, the digital tip should appear white and swollen.

HEMOSTASIS — A digital tourniquet (picture 4) may be required to achieve hemostasis. A flat Penrose drain wrapped around the base of a digit with its ends clamped together using a hemostat may be used [11,28]. A sterile glove with the tip of a glove finger removed and the remainder rolled back to the base of the finger may provide hemostasis and also a sterile field (picture 5) [1,11].

Digital tourniquets should not be left in place for more than 15 minutes to avoid prolonged digital ischemia. If necessary, the tourniquet can be removed for one to two minutes during the procedure to allow the digit to reperfuse before retightening the tourniquet.

As an alternative to the application of a digital tourniquet, hemostasis may be achieved by having an assistant apply pressure to the sides of the digit during the procedure (picture 6) [1].

BASIC SURGICAL PROCEDURES

Nail plate avulsion — Complete or partial nail plate avulsion is indicated in most nail surgeries to achieve maximum exposure of the nail bed and matrix (picture 7). When possible, partial nail plate avulsion is preferred to complete avulsion because it minimizes trauma to the adjacent tissues [29]. Partial nail avulsion is performed using the same principles used for complete nail avulsion. (See "Nail avulsion and chemical matricectomy", section on 'Nail avulsion'.)

Full nail unit excision or en bloc excision — The en bloc excision of the nail unit is a treatment modality for primary malignant nail tumors such as melanoma in situ and squamous cell carcinoma (SCC). In patients with SCC, en bloc excision is generally preferred if the bone is not involved or if Mohs surgery cannot be performed. (See 'Squamous cell carcinoma' below.)

Before en bloc excision, the planned excision margins should be marked. Proximal margins generally include a line drawn transversely at about 50 to 75 percent of the distance between the distal interphalangeal joint crease and the cuticle to ensure that the nail matrix is fully excised (picture 8) [30]. This line should form a 90⁰ angle with the lateral nail folds bilaterally. Lines should also be drawn along each of the lateral nail folds and meet at least 2 mm distal to the hyponychium on the distal digital tip. These margins may be widened on a case-by-case basis.

Although surgical techniques vary, one approach is to start the incision at a lateral edge just dorsal to the distal transverse line to simplify access to the correct plane of dissection, which is at the level of the periosteum, and proceed dorsally to reach the dorsal surface of the phalanx [30]. The procedure is then repeated on the other side (picture 9). Blunt tipped scissors angled "tips down" can be used to cut proximally to the level of the extensor tendon located approximately 12 mm proximal to the cuticle (picture 10A-B). Once removed, the tissue specimen should be marked with single sutures placed on the proximal and distal aspects and the radial and ulnar aspects inked to ensure correct orientation of the specimen during pathologic processing.

Several options exist for tissue repair [30]. Some surgeons perform a full-thickness skin graft with potential graft donor sites including the hypothenar eminence, clavicular area, pre- or post-auricular areas, or upper inner-arm area. Others surgeons prefer to allow the defect to heal by secondary intention alone. However, secondary intention healing may require up to several months. A split-thickness skin graft offers reliable graft survival but less-than-ideal color and texture match and less protection of the distal phalanx than full-thickness skin graft. For the thumb or index finger, a cross-finger flap can be used.

SPECIAL SITUATIONS IN NAIL SURGERY

Longitudinal melanonychia — The evaluation and surgical management of longitudinal melanonychia are discussed separately. (See "Longitudinal melanonychia".)

Longitudinal erythronychia — Longitudinal erythronychia limited to a single digit is usually caused by a tumor of the nail matrix and/or nail bed. (See "Overview of nail disorders", section on 'Longitudinal erythronychia'.)

A full thickness longitudinal elliptical (fusiform) excision is generally considered the technique of choice for longitudinal erythronychia, since the relevant pathology lies in the distal matrix and usually extends into the nail bed [31,32]. (See "Nail biopsy: Indications and techniques", section on 'Longitudinal elliptical excision'.)

Following complete or partial nail avulsion, a longitudinal elliptical biopsy is performed, starting at the mid to distal matrix, extending through the nail bed to the hyponychium (picture 11) [32].

The defect may be left to heal by secondary intention. However, undermining and side-to-side suturing of the matrix with absorbable suture material minimizes the risk of postoperative nail dystrophy. (See 'Complications' below.)

Onychomatricoma — Onychomatricoma is a rare benign fibroepithelial tumor that originates from the nail matrix. (See "Overview of nail disorders", section on 'Onychomatricoma'.)

Surgical removal of an onychomatricoma begins with two releasing incisions at a 45° angle at the junction of the proximal and lateral nail folds [33]. The proximal nail fold is then reflected backward using skin hooks or suture. To expose the tumor, proximal plate avulsion or lateral curled avulsion is performed (picture 12). During nail plate avulsion, it is important to avoid tearing the tumor digitations. Using a scalpel blade, the tumor is excised from the matrix. Following tumor removal, the releasing incisions of the proximal nail fold are sutured or approximated and secured with Steri-Strips.

A nonadherent dressing can be placed under the proximal nail fold and secured with sutures to avoid any adherence between the ventral nail fold and the matrix [33]. The nail plate should be sent along with the tumor for pathologic examination since tumor digitations are typically found within the nail plate. (See 'Managing the surgical specimen' below.)

The sutures of the releasing incisions can be removed after approximately seven days. The sutures securing the nonadherent dressing should be removed after three weeks. The excision of an onychomatricoma is usually followed by the regrowth of a normal nail. However, nail plate dystrophy, usually mild, may occur.

Digital myxoid cyst — A digital myxoid cyst (DMC) typically presents as a translucent nodule on the dorsum of the digit between the distal interphalangeal joint and the proximal nail fold (picture 13A-B). (See "Overview of nail disorders", section on 'Digital myxoid cyst or myxoid pseudocyst'.)

A wide range of therapies are used to treat or remove DMCs, including cryotherapy, intralesional corticosteroid injection with 3 to 5 mg/mL triamcinolone solution, percutaneous sclerotherapy with sodium tetradecyl sulfate or polidocanol [34,35], and surgical removal [36,37]. Although surgical removal achieves cure rates of over 90 percent for fingernails, it is associated with a risk of septic osteoarthritis [38].

Squamous cell carcinoma — Squamous cell carcinoma (SCC) of the nail bed and lateral nail groove is the most common malignant tumor of the nail unit [1]. The clinical features of this tumor are often minimal and nonspecific, causing a long delay in the diagnosis [1,39]. (See "Overview of nail disorders", section on 'Squamous cell carcinoma'.)

The treatment of choice for SCC of the nail apparatus without bone involvement is Mohs surgery or en bloc excision [1,40]. (See "Mohs surgery" and 'Full nail unit excision or en bloc excision' above.)

In cases involving invasion of the underlying bone, amputation may be required.

Glomus tumors — Glomus tumor is a rare benign tumor composed of cells resembling the smooth cells of the normal glomus body [41]. It presents as a red to purple or blue lesion under the nail plate (picture 14A-D) [41-43]. (See "Overview of benign lesions of the skin", section on 'Glomus tumor' and "Overview of nail disorders", section on 'Glomus tumor'.)

Treatment of glomus tumors is surgical excision. The location of the glomus tumor under the nail plate must be marked before anesthetic injection or tourniquet application, since exsanguination precludes the visualization of the tumor [43]. To expose the tumor, a partial nail plate avulsion, such as a trap door avulsion or a lateral curled nail avulsion, is preferred (picture 15) [43].

In the trap door avulsion, the nail plate remains attached proximally over the proximal nail matrix, with full access to the underlying hyponychium, nail bed, and distal nail matrix [29]. This avulsion technique is less frequently associated with postoperative complications, such as paronychia and pterygium than complete avulsion.

When complete exposure of the proximal matrix and eponychium is necessary, the lateral curled nail plate avulsion is ideal. The lateral curled avulsion is best performed using a hemostat, first to undermine the isolated lateral portion of the nail apparatus and then to clamp and roll the loosened nail plate away from the nail sulcus.

Following nail plate avulsion, the tumor is dissected from the surrounding tissues with blunt curved scissors (picture 16) [43]. The nail bed defect can be closed with absorbable sutures if larger than 3 to 4 mm. The avulsed portion of the nail plate is often replaced and secured to the lateral and distal nail folds to protect the surgical site (picture 17A-B). Although the nail plate will not reattach permanently, it will protect the wound for several weeks until it is pushed out by a newly growing nail plate [29,43]. The entire glomus tumor must be enucleated to prevent recurrence. Glomus tumors that occur in or under the nail matrix are the most difficult to excise and have the highest risk of recurrence because of incomplete removal [44].

A nail bed margin approach has also been proposed [45]. A nail bed margin incision on the side of the tumor is performed under an operating microscope and the nail bed is dissected and elevated to expose the tumor. The tumor is carefully enucleated and resected completely using microsurgical scissors to minimize damage to the nail bed. The nail bed flap is then placed back into its original position and sutured.

Subungual exostosis — Subungual exostosis is a benign osteocartilaginous tumor that most commonly occurs on the dorsomedial aspect of the tip of the great toe in adolescents or young adults [46]. (See "Overview of nail disorders", section on 'Subungual exostosis'.)

Complete surgical excision of the lesion, including its cartilaginous cap, provides definitive treatment. After appropriate anesthesia by proximal or distal (wing) nerve block, a tourniquet is applied to achieve exsanguination. A complete or partial nail avulsion by trap door or lateral curled avulsion techniques is then performed. These procedures are discussed above (see 'Glomus tumors' above). The nail plate is preserved and replaced as a surgical site cover at the end of the procedure [46,47].

The nail bed is then incised and the bony proliferation dissected at the base with a bone rongeur or sterile dual action nail nippers. The distal phalanx cortical bone is vigorously curetted to remove any remaining tumor cells. The surgical defect in the nail bed can be closed with absorbable suture. Defects >4 mm should be undermined to allow the approximation of the lateral margins and sutured. Following defect closure, the nail plate can be replaced and secured for protection.

If the nail plate is distorted by the underlying tumor, a v-cut in the middle of the plate may flatten it and allow the distal edge be secured to the distal fold with sutures [46].

Patients should be encouraged to apply adhesive tape to the nail plate to keep it in place for as long as possible to prevent distal embedding. Typically, a normal appearing nail grows following surgery.

Pincer nails — A pincer nail is characterized by a transverse overcurvature of the nail plate that can cause significant pain and tenderness (picture 18). Toenails develop this deformity more frequently than fingernails [46,48,49]. Pincer nails may be genetically inherited or occur as a consequence of trauma, surgery, foot deformations, chronic dermatoses, or osteoarthritis. In some instances, the deformity is caused by an enlargement of the distal phalanx secondary to lateral osteophyte formation. As the distal phalanx enlarges, the proximal nail plate flattens and causes an increased curvature of the distal nail plate.

Treatment of pincer nail deformity may be conservative or surgical. Nonsurgical methods include nail thinning (by mechanical abrasion or long term use of keratolytics such as 40% topical urea paste) or nail braces (steel or plastic devices adapted to the curvature of the nail plate and gradually adjusted to exert a counter tension on the nail plate) [46,49,50]. However, recurrence is usual after nonsurgical treatments.

Surgical treatments of pincer nails include selective resection of the nail matrix horns; chemical ablation of the matrix horns with phenol, which is applied to the nail matrix with a cotton swab for one minute three times and then rinsed with alcohol or water phenol; or a combination of the two.

Chemical matricectomy is discussed in detail separately. (See "Nail avulsion and chemical matricectomy", section on 'Chemical matricectomy'.)

Matrix horn resection plus nail bed plasty is complex procedure. Under digital block anesthesia, lateral nail strips or the entire nail are avulsed. The digit is exsanguinated by using a tourniquet and the matrix lateral horn dissected and removed or phenolized. The nail bed is then incised along the median line from the lunula to the hyponychium down to the bone [46]. The pinched nail bed is dissected from the terminal phalanx and reflected laterally. Any underlying osteophyte of the dorsal end of the distal phalanx is removed by using a bone rongeur or sterile dual action nail nippers. The nail bed flaps can be closed with absorbable suture. Several variations of nail bed plasty have been described [51-54].

Nail bed plasty is associated with severe postoperative pain requiring appropriate analgesic medications. (See 'Postoperative care' below.)

Healing is typically complete after approximately four weeks regardless of the surgical technique used. Patients should be warned that oozing generally appears after three days and remains for one to two weeks [46].

MANAGING THE SURGICAL SPECIMEN — Following a surgical excision, the tissue specimen should be correctly oriented and marked so that the pathologist can appropriately evaluate the histology. A requisition form that thoroughly describes the clinical picture to the pathologist should be completed at the time of biopsy. Additionally, a nail map can help the pathologist identify the biopsy site and orient the epidermal surface (picture 19) [1,55]. A record of the biopsy should be maintained in the office and signed at the time the result is relayed to the patient to ensure adequate patient communication concerning diagnosis and management.

POSTOPERATIVE CARE — Appropriate dressing can minimize postoperative pain and complications [1]. Many nail surgeons apply the initial dressing themselves to determine the appropriate level of pressure needed to maintain hemostasis without causing a tourniquet effect. A layer of antibiotic ointment is usually applied to the surgical site before dressing. Patients should be instructed to loosen the original bandage if pain due to pressure worsens, since postoperative edema may cause the original bandage to tighten, thereby functioning as a tourniquet. The patient should elevate the digit above the heart to minimize swelling and painful throbbing.

The original bandage should be kept dry and left in place for 24 to 48 hours and changed daily thereafter until complete healing [1,12]. Dried blood may cause adherence of the bandage to the surgical site. Soaking the dressing in warm tap water before its removal can minimize discomfort. The wound should be cleaned with half-strength hydrogen peroxide (3% over-the-counter hydrogen peroxide diluted with an equal amount of tap water) before reapplying antibiotic ointment and a clean padded dressing. On average, fingernail regrowth takes approximately 6 months and toenail regrowth about 12 months and up to 18 months for the great toenail [6].

Postoperative analgesics, such as acetaminophen, codeine, or nonsteroidal anti-inflammatory drugs (NSAIDs), may be necessary for adequate pain control [1]. Pulsating pain beginning 36 to 48 hours after surgery may indicate infection and prompt appropriate antibiotic treatment.

COMPLICATIONS — The most common nail surgical complication is permanent nail plate dystrophy (eg, nail splitting, ridging, or pterygium formation), which results from nail matrix damage. Nail dystrophy occurs more frequently when the biopsy site is located within the proximal nail matrix [56].

Midline nail unit biopsies are associated with a high risk of split nail plate deformity (picture 20). The deformity results from scarring within the nail matrix, most frequently after biopsies that are >3 mm. Closing the matrix defect with fine absorbable suture may prevent the split nail complication. A nail split may also occur as a consequence of pterygium (adherence between the proximal nail fold and the nail matrix after nail plate removal). Pterygium may be prevented by separating the proximal nail fold from the nail bed with nonadherent gauze, a stent, or the original nail plate. A split nail can be repaired by excision of the matrix scar followed by careful repair or, for wide matrix scars, by free matrix graft, using the big toe as donor site [57].

Nail plate misalignment is typically associated with the lateral longitudinal nail biopsy technique, particularly when the biopsy is >3 mm in width [56,58]. Nail misalignment can be treated by surgical realignment of the matrix or total matricectomy [56,58]. (See "Nail biopsy: Indications and techniques", section on 'Lateral longitudinal excision'.)

Partial or total chemical matricectomy may be associated with nail spicule recurrence due to incomplete destruction of the lateral or subproximal matrix. Chemical ablation is associated with the risk of tissue necrosis, pain, persistent exudative drainage, and periostitis [56]. Surgical matricectomy is thus preferred by some surgeons because of the lower risk for nail spicule formation. (See "Nail avulsion and chemical matricectomy", section on 'Chemical matricectomy'.)

A distal nail fold may form when an overlying nail plate is lacking for an extended period of time, as in the case of a great toenail avulsion [3]. Although a distal nail fold is usually pushed down by the regrowing nail plate, when present for a long period of time it may become fibrotic, fixed, and interfere with further outward nail plate growth. Under these circumstances, compression of the distal nail fold by taping or removal of the distal nail fold by crescentic wedge excision may be necessary.

A pyogenic granuloma may develop following nail surgery (picture 21). It may be removed by cautery, scalpel excision, laser, or silver nitrate application [56]. (See "Pyogenic granuloma (lobular capillary hemangioma)", section on 'Management'.)

Nail bed scarring results in persistent onycholysis [56]. Epidermal inclusion cysts can occur during suturing when needle trauma causes invagination of a small piece of epidermis into the subcutaneous layer [56,59]. Other nail surgical complications include anesthetic allergy, bleeding, infection (including superficial infection, acute purulent tenosynovitis, osteomyelitis, and septic arthritis), hematoma formation, persistent pain and swelling, and reflex sympathetic dystrophy due to traumatic nerve injury [56,60].

SUMMARY AND RECOMMENDATIONS

●Preoperative evaluation and preparation – The preoperative evaluation of the patient undergoing nail surgery includes a complete history (table 1) and targeted physical examination. Antibiotic prophylaxis is generally not necessary, but may be indicated in patients at increased risk of postoperative infection (table 2). (See 'Preoperative evaluation and preparation' above and 'Antibiotic prophylaxis' above.)

●Anesthesia:

•Anesthetic agents – Lidocaine 1 to 2% with epinephrine 1:100,000 is used for local anesthesia in most patients. However, epinephrine should be avoided in patients with peripheral vascular disease who are at increased risk for digital ischemia or infarction. (See 'Anesthetic agents' above.)

•Administration – Anesthesia can be administered by digital nerve block or wing block procedure. The wing block is preferred because it is less painful, requires a smaller amount of anesthetic, and is more rapid than the digital nerve block. (See 'Procedure' above.)

●Basic procedures:

•Nail avulsion – Complete or partial nail avulsion is indicated in most instances to achieve maximum exposure of the nail bed and matrix (picture 7). (See "Nail avulsion and chemical matricectomy", section on 'Nail avulsion'.)

•Full excision of the nail unit – The en bloc excision of the nail unit is a treatment option for primary malignant nail tumors such as melanoma in situ and squamous cell carcinoma (SCC). (See 'Full nail unit excision or en bloc excision' above.)

●Special situations – Nail conditions requiring specific surgical approaches include:

•Longitudinal melanonychia (see "Nail biopsy: Indications and techniques", section on 'Nail matrix biopsy')

•Longitudinal erythronychia (see 'Longitudinal erythronychia' above)

•Onychomatricoma (see 'Onychomatricoma' above)

•Digital myxoid cyst (see 'Digital myxoid cyst' above)

•Squamous cell carcinoma (see 'Squamous cell carcinoma' above)

•Glomus tumor (see 'Glomus tumors' above)

•Subungual exostosis (see 'Subungual exostosis' above)

•Pincer nails (see 'Pincer nails' above)

●Management of the surgical specimen – Following surgical excision, the tissue specimen should be correctly oriented and marked so that the pathologist can appropriately evaluate the histology. A nail map is helpful to identify the biopsy site and orient the epidermal surface (picture 19). (See 'Managing the surgical specimen' above.)

●Postoperative care – Measures to control postoperative pain include appropriate dressing, digit elevation above the heart level, and oral analgesics. The original bandage should be kept dry and left in place for 24 to 48 hours and changed daily thereafter until complete healing. (See 'Postoperative care' above.)

●Complications of nail surgery – The most common complication of nail surgery is permanent nail dystrophy (eg, nail splitting, ridging, or pterygium). Other complications include nail misalignment, nail spicule recurrence, distal nail fold, pyogenic granuloma, and onycholysis. (See 'Complications' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Julie A Jefferson, MD, who contributed to an earlier version of this topic review.