Nail Surgery 

Updated: Feb 15, 2019
Author: Neh Onumah, MD; Chief Editor: William D James, MD 

Overview

Background

The nail complex is the structural and functional unit of the nail. The nail consists of the plate; bed; matrix; proximal, lateral, and distal grooves; proximal and lateral folds; and hyponychium (see the image below).[1, 2, 3] Aside from being aesthetically appealing, the healthy nail unit has the important function of protecting the distal phalanges, fingertips, and surrounding soft tissues from external injury, as well as enhancing precise delicate movements of the distal digits through the mechanistic action of counterpressure exerted over the volar skin and pulp.[4, 5]

Longitudinal section of a digit showing the dorsal Longitudinal section of a digit showing the dorsal nail apparatus (top). Component part of the nail apparatus (bottom).

See 15 Fingernail Abnormalities: Nail the Diagnosis, a Critical Images slideshow, to help identify conditions associated with various nail abnormalities.

Performing successful nail surgery requires a comprehensive understanding of nail anatomy and physiology.[6, 7] An understanding of both the vascular and neural pathways supplying the nail complex and the functions and relationship of each component of the nail unit is also essential. Thus, the nail surgeon should be equipped with knowledge of nail pathology, surgical techniques and instrumentation, anesthesia, preoperative evaluation, management of complications, and wound care and healing after surgery. This knowledge ensures minimal patient discomfort, maximal patient satisfaction, and optimal surgical success. With these goals in mind, this article reviews the nail anatomy and focuses on common nail pathologies with the corresponding surgical techniques used for their diagnosis and treatment.

Indications

Multiple indications for surgical exploration of the nail unit exist; most of the indications range from infectious and inflammatory to neoplastic and traumatic causes. Some commonly encountered disease processes affecting the nail complex include onychomycosis (ie, fungal infection), onychocryptosis (ie, recalcitrant ingrown nails), onychogryphosis (ie, hornlike hypertrophy of the nail plate), and onychauxis (ie, thickened nails), as well as psoriasis, lichen planus, congenital nail dystrophies, and tumors. In addition, nail surgery is frequently performed to aid in a suspected diagnosis, to relieve pain, and to correct or prevent anatomical deformities of the nail.

Paronychia

Acute paronychia is an acute inflammation of the nail fold and frequently results from minor trauma, such as an accidental break in the skin, a splinter in the distal edge of the nail, a thorn in the lateral groove, a hang nail, or excessive nail biting leading to infection of the surrounding soft tissues.[1, 8, 9] The infectious process initiates in the lateral perionychium and is followed by the development of erythema, intense inflammation, swelling, pain, and local tenderness. While the timing of the presentation may vary, it is often 2-5 days after the initial trauma.[10] Vesicles and blisters may also form.

Chronic paronychia is characterized by acute exacerbations of self-limiting inflammation and infection followed by remissions. Chronic paronychia commonly occurs in hands that are repeatedly exposed to water.[11] The proximal nail fold (PNF), the lateral nail fold (LNF), and the cuticle are destroyed. The potential barrier formed by the PNF is impaired, and the cuticle eventually detaches from the nail plate. The loss of seal creates a nidus for retention of moisture, bacterial or fungal pathogens, and irritants to accumulate within the nail bed grooves, leading to further exacerbation.[12]

The warm moistened environment is ideal for bacterial proliferation. Secondary Candida and bacterial infections (eg, Pseudomonas aeruginosa, Staphylococcus aureus) are implicated in acute exacerbations.[13] Exacerbations may be initiated through contact with irritants and allergens. Chemical and irritant contact dermatitis is common. Exacerbations usually resolve several days after abscesses spontaneously drain, but they lead to prolonged edema and fibrosis of the nail folds.[13] Factors to consider when assessing management options include etiology, duration, extent of paronychial involvement, and associated risk factors present such as contact with oral secretions or exposure to animals.[10]

Onychocryptosis

In onychocryptosis (ingrown nail), the toenails are most commonly affected; the fingernails are rarely afflicted. Predisposing factors involved in the pathogenesis of an ingrown nail include congenital malalignment of the digit; hyperhidrosis (commonly occurs in athletic adolescents); increased pressure from external sources (eg, trauma); poorly fitted shoes; poor posture and gait; excess internal pressure, which results in overcurvature of the nail plate; incorrectly trimmed nails or naturally short nails; underlying systemic disease (eg, obesity, diabetes mellitus); arthritis; skeletal disease; onychomycosis and other diseases that result in abnormal changes in the nail plate; and senile nail diseases (eg, onychauxis, subungual hyperkeratosis).[2, 8, 14]

In onychocryptosis, the primary direction of nail growth is lateral instead of the normal, forward orientation of nail growth in the longitudinal plane. A more pronounced transverse curvature of their toenails increases the likelihood of developing ingrown toenails.[15] The laterally curved edge of the nail plate, or the nail spicule, penetrates the adjacent LNF, perforating the fold skin and the surrounding dermal components. Perforation of the lateral fold skin results in painful inflammation that manifests clinically as mild edema, erythema, and pain.[13] In advanced stages, drainage, infection, ulceration, and hyperhidrosis may be present. Hypertrophy of the lateral nail wall occurs, and granulation tissue forms over the nail plate and the nail fold during healing of the ulcerated skin. The resulting edema further exacerbates the problem by compressing the lateral dermal tissue between the sharp nail plate and the bony phalanx.

Failure to destroy or remove the lateral horn of the matrix can result in identical regrowth of the former nail, which reintroduces an epidermal breakage and a larger regrown nail.[15]

Myxoid cysts

Myxoid cysts are dome-shaped, translucent, solitary nodules occurring on the dorsal aspect of the finger.[13, 16, 17] Occasionally, the toes may develop these cysts in a similar location. Typically, the cysts are lateral to the midline between the PNF and the distal interphalangeal (DIP) joint.[16] The cysts measure 4-10 nm in diameter and result in a longitudinal depression in the nail plate, as a result of pressure on the matrix.[18] Their pathogenesis and etiology have not been clearly established.

Myxoid cysts occurring on the DIP joint have been associated with the formation of a tract or communication with the joint. The cysts are believed to occur secondary to degenerative disease of the DIP joint and in association with marginal osteophytes, thus explaining their presence in patients with osteoarthritis.[13, 19] As a result, myxoid cysts are frequently mistaken for synovial cysts. Myxoid cysts of the PNF may result from increased synthesis of hyaluronic acid by local fibroblasts.[13, 20] Whether or not these mechanisms of cyst formation occur is controversial.

Warts

Periungual and subungual warts are benign, fibroepithelial tumors that commonly affect the paronychial region of the nail unit. Also referred to as common warts, these hypertrophic growths have a rough, keratotic surface and tend to occupy the nail grooves, the retroungual nail folds, and the subungual area under the nail plate. Periungual and subungual warts are the single most common benign tumors of the perionychium and are caused by the human papillomavirus (HPV). In children, warts caused by HPV are most commonly found on the dorsal aspect of the distal interphalangeal (DIP) joint.[21]

Certain subtypes of HPV associated with periungual and subungual warts may cause squamous atypia. Usually, these warts are mildly infective tumors and present as multiple lesions. However, they appear to be more aggressive and destructive than other types of common warts in this location.[13]

In the absence of fissuring, periungual warts are usually asymptomatic. Subungual warts initially infect the hyponychium, gradually move toward the nail bed, and lastly involve the nail plate. They commonly cause pain. Typically, the nail plate is spared, except for ridging that occurs on the surface of the nail plate.

The differential diagnosis in clinical presentations of periungual and subungual warts should include epidermoid carcinoma and keratoacanthoma.[1, 8] The warts may be mistaken for a glomus tumor. The spread of periungual warts is assisted by biting and picking the nail and surrounding soft tissue. Picking infected lesions can lead to autoinoculation of noninfected fingers.[8, 11, 22]

Common warts under the proximal nail fold cause a swelling, similar to chronic paronychia.[18] Common warts in the posterior nail fold may exert pressure on the matrix, resulting in a deformed nail plate. If left alone, periungual and subungual warts tend to linger and persist as they continue to grow and invade the skin of the other neighboring digits.

Nail trauma

Traumatic injuries of the nail unit include simple or complex lacerations, crush injuries, avulsions, terminal phalanx fractures, and partial or complete hematomas. Preservation of nail structure and function is the most important consideration when managing injuries to the nail complex. To ensure optimal management in cases of nail unit trauma, early treatment of the patient should be initiated. The goal is to explore and repair the wound within hours or days of the injury. Sometimes, the wound is still capable of repair 1-2 weeks following the injury.

Subungual hematoma

Acute subungual hematoma frequently results from blunt trauma to the underlying vascular nail bed. Subungual hematoma may result from chronic repeated injury to the nail caused by minor trauma, such as trauma of the toenail from poorly fitted shoes. They may also occur in older patients with atrophy of the skin and nails.[11] Bleeding ensues, and the accumulated blood is limited to the subungual compartment of the nail unit. A hematoma develops and is accompanied by inflammation and severe pain due to increased pressure of the entrapped blood on the subungual tissue and underlying periosteum.

When acute subungual hematomas are directly under the transparent nail, they have an immediate onset and are conspicuous. In acute subungual hematoma, the nail color is initially red and changes to black after coagulation.[11] The hematoma is uniform in color with sharply demarcated margins, and it usually grows distally with the nail plate until reaching the free distal edge of the plate where it is no longer seen. Occasionally, the hematoma may persist under the nail and does not move distally with nail growth.

Hemorrhages resulting from trauma to the dorsal nail fold may not appear with forward nail growth for several days. The differential diagnosis of subungual hematoma should include melanoma, glomus tumor, Kaposi sarcoma, basal cell carcinoma, squamous cell carcinoma (SCC), exostosis, melanonychia striata, fungal melanonychia, and keratoacanthomas, all of which must be excluded.[23] To exclude a diagnosis of melanoma, biopsy must be performed in all pigmented lesions of unknown etiology.

Lacerations

Simple superficial lacerations of the nail are usually confined to the nail plate, nail bed, and LNFs. Complex lacerations involve the nail matrix and PNF and result in partial or total nail avulsion or fragmentation of the nail plate; in complex avulsive lacerations, the finger pulp, nail bed, and distal phalanx are destroyed.[23] Complex lacerations may lead to serious complications after injury and should be promptly treated to prevent abnormal nail morphology and function.

Fractures

A major function of the distal phalanx is to support the distal soft tissues of the finger.[24] Fracture of the distal phalanx occurs in approximately one half of nail bed injuries. The type of fracture (open vs closed),[23] the position of the fracture, and the extent of comminution determine treatment. Healing of the fracture is mostly related to the degree of initial displacement and soft tissue injury.

Splinter hemorrhage

Most commonly, trauma or certain disease processes easily injure the small, fine capillaries that line the epidermal-dermal ridges on the nail bed.[1, 8] Splinter hemorrhages result from the extravasation of blood into the potential space between the nail plate and the nail bed after capillaries are disrupted. They develop in the long axis of the nail bed, which conforms to the orientation of the dermal ridges and the subungual vessels.

Other etiologic factors are associated with the formation of splinter hemorrhages in the nail bed; the hemorrhages may clinically occur in such conditions as psoriasis, vasculitis, bacterial endocarditis, arterial embolism, lupus, Darier disease, cirrhosis, hemochromatosis, thyrotoxicosis, and trichinosis.[1, 8, 25] Certain drugs (eg, tetracycline) and drug reactions may also induce their formation. The hemorrhages may be single or multiple, and they appear as brown, red, or black linear streaks, usually in the distal one third of the nail.[8] As the nail grows, the hemorrhages move distally and superficially. They do not tend to blanch on palpation of the nail plate.

Splinter hemorrhages that occur proximally near the lunula are frequently associated with systemic disease.[25] Involvement of multiple nails by these hemorrhages may indicate the presence of an underlying systemic disease. Overall, splinter hemorrhages occur most often in males and in blacks. They commonly involve the thumb and index finger of the dominant hand. However, in studies with single and multiple hemorrhages, the left thumb was found to be the most frequently involved digit.

Nail unit tumors

High-resolution MRI gained prominence in the noninvasive diagnosis of nonmelanoma nail tumors and is capable of detecting lesions that are smaller than or equal to 1 mm in diameter.[26] This modality is helpful in identifying lesions in the following presentations of benign and malignant tumors of the nail: glomus tumors, periungual fibromas or fibrokeratomas, mucous cysts, and exostoses.

Pyogenic granuloma

Pyogenic granuloma is a benign granulomatous lesion commonly seen after a minor trauma penetrates the skin. It usually starts as a small, red papule on the PNF and rapidly grows to the size of a pea.[8, 11] Pyogenic granuloma may also localize to the nail bed after a trauma penetrates the overlying nail plate. Erosion of its surface by pressure necrosis of the overlying epidermis may occur.

Fibroadenoma

Various types of fibroadenoma may occur in the periungual or subungual region. They are usually distinctive in their etiology and presentation.

Glomus tumor

A glomus tumor is a small, well-differentiated, hamartomatous growth of the soft tissues encapsulated in a fibrous covering. A glomus tumor appears as a small, blue or reddish blue spot that is visible through the nail plate.[8, 11, 17] Most commonly, the tumors are localized to the hand with involvement of the fingertips and the subungual region. Ultrasonography can be used to identify and locate the tumors. The onset of intense pulsating pain with the slightest pressure or with exposure to cold temperatures is pathognomonic for subungual glomus tumors. Microscopically, all the components in a glomus body are present in this tumor; the components are an afferent arteriole, an efferent venule, glomus cells, smooth muscle cells, and myelinated and nonmyelinated nerves.[8, 27, 28]

Subungual exostosis

Subungual exostoses are painful outgrowths of healthy bone or remnants of calcified cartilage that frequently occur on the great toe in young persons.[8, 11] Subungual exostosis is not a true tumor.[8] Trauma has been implicated as the inciting cause. The exostosis begins as a small elevation on the dorsal surface of the terminal phalanx. Over time, it may appear as an outgrowth under the distal nail edge, or it may completely destroy the nail plate, creating an environment for tissue erosion and infection. Clinically, patients present with pain that may be accompanied by an abnormal gait because of difficulty walking and a deformed nail. The differential diagnosis includes osteochondroma, which has a similar presentation.

Malignant neoplasm of the nail apparatus

It is likely that the most common malignant neoplasm of the nail subunit is melanoma. Hence, it is not surprising that the majority of these malignant lesions present as pigmented brown-to-black streaks, qualifying as longitudinal melanonychia. The location of the pigmented streak in the nail subunit largely determines the surgical approach that should be used. Interestingly, melanomas confined to the nail bed often present without pigment and are amelanotic.[18]

An elliptical or punch biopsy is typically performed for pigmented streaks in a median position, or a complete horizontal excision may be used. A lateral longitudinal nail biopsy is used for brown streaks in a lateral position.[18]

A confirmed diagnosis of nail melanoma is managed surgically by total excision of the entire nail unit with confirmed negative tissue margins on histopathology. The resulting defect can be repaired with a cross-finger flap or a full-thickness skin graft. Melanomas of the nail apparatus measuring greater than 1 mm in depth require distal amputation.[18]

Relevant Anatomy

The nail plate, the largest segment of the nail unit, is a dense, keratinous horny structure derived from the germinal matrix, or nail root.[1, 2, 3, 4, 5] Destruction of the nail root, despite an intact nail bed, results in permanent loss of the nail plate. Nail growth occurs in a forward distal direction, and growth of the nail plate is directly proportional to the turnover rate of cells in the matrix. Complete growth of the fingernail plate, measured from the matrix to the distal free edge of the plate, is estimated to occur every 4-6 months, corresponding to a rate of 0.1 mm daily.[1, 2, 3, 29] The turnover time for the toenail plate is longer, averaging around 12-18 months.[1, 2]

See the image below.

Longitudinal section of a digit showing the dorsal Longitudinal section of a digit showing the dorsal nail apparatus (top). Component part of the nail apparatus (bottom).

Grossly, the nail plate is composed of 3 distinct layers: a dorsal thin layer, a thick intermediate layer, and a ventral layer.[4, 5] The nail plate originates beneath the PNF and can be seen passing over the lunula.[30] and the richly vascularized nail bed where it firmly attaches. The nail plate is bordered by the PNF and LNFs, and it is distally adjoined by the hyponychium, although its free distal border generally extends beyond the distal phalanx. The healthy nail plate appears as a smooth, convex, nearly rectangular, translucent structure that has a pink color when light is reflected from its surface; the color is due to the underlying vascular-enriched nail bed.[1, 4, 5]

The shape of the nail plate largely conforms to the convexity of the distal margin of the lunula, the visible crescent-shaped distal segment of the matrix. The nail plate exhibits a thickness gradient with the nail thickness, increasing proximally to distally and with age. Thus, the nail plate tends to be thinner at the lunula.[1, 4, 5, 31] Nail thickness is directly related to the length of the matrix.[1, 29] In darkly pigmented persons, a hyperplasia of melanocytes is commonly seen throughout the matrix epithelium, resulting in longitudinal linear bands of light brown to black pigment visible through the nail plate.[1, 29, 32] Although the linear bands of pigment may represent pathological states, they may be a normal finding in people of color, secondary to hyperproduction and accumulation of melanin.

The onychodermal band is the narrow, transverse delineation at the distal end of the nail plate. This band appears yellowish white in whites or reddish brown in darkly pigmented persons. The onychodermal band marks the point of separation of the nail bed from the nail plate,[14] and it appears to be important in preventing onycholysis after trauma. This band may be prominent in cirrhosis, acrocyanosis, and other chronic diseases.[3, 8] The onychodermal band has been postulated to have a separate vascular supply from the rest of the nail bed.[4, 5, 11]

Hyponychium

The hyponychium is the anatomical area that begins at the onychodermal band, where the nail bed ends, and terminates at the distal groove. The distal groove is a transverse demarcation extending across the distal digit that divides the hyponychium from the volar epidermis of the digit. This groove is the first component of the nail unit to be recognized during the embryologic period, and it is the origin point of the volar epidermis.[1] In persons who bite their nails, the distal groove is easily identified.[1]

The solehorn is the ventral cuticle layered between the ventral nail plate and the distal nail bed; it functions as a potential waterproof barrier.[29] in the space created by its firm attachment to the nail plate and the distal bed epithelium. In this capacity, the solehorn prevents the entrance and invasion of offending organisms and, therefore, protects the nail plate from infection (eg, distal subungual onychomycosis). Frequent aggressive manicuring of the hyponychial area results in disruption of this barrier and allows microbes to enter it.

Proximal nail fold

The PNF is a continuation of the dorsal skin of the digit that folds back on itself at the nail root to create 2 epithelial surfaces: a superficial dorsal layer and a deep ventral layer.[3, 4, 5, 14] The ventral layer travels to the base of the nail plate to create the nail matrix. Thus, the PNF obscures most of the nail root (germinal matrix) and the area where the proximal nail plate embeds itself into the proximal groove.

The PNF is contiguous with the LNFs that border the nail plate. Where the 2 epithelial surfaces meet, the cuticle converges onto the distal nail plate.[3, 4, 5] The cuticle is the horny end product of the PNF, adhering to the dorsal wall of the nail plate. It is the true nail vest that appears as a fine white band.[29] The role of the cuticle is similar to that of the solehorn; it functions as an impermeable barrier, sealing off the potential area that exists between the PNF and the nail plate. Eventually, the cuticle is shed like the cornified horny layer of epidermal skin.

When the cuticle is disrupted, usually due to overzealous manicuring.[29] the individual becomes susceptible to paronychia and other infectious and inflammatory diseases. Damage to the cuticle can also result in increased chemical insults, such as irritant contact dermatitis.[8] Loops of blood capillaries are sometimes found in and around the PNF, and they may be pathognomonic for certain diseases, such as dermatomyositis and lupus erythematosus. However, the loops may be a normal finding in certain individuals.[1, 4, 5, 11]

Nail matrix

The nail matrix is the germinative portion of the nail complex, giving rise to the nail plate.[1, 4, 5, 11, 29] The matrix is at the most proximal point of the nail bed and is seated deep beneath the PNF; it is separated from the distal phalanx by only a few millimeters. According to Zaias, "the top half of the nail plate (the dorsal aspect) is derived from the proximal matrix, while the derivation of the lower half (the ventral aspect) is from the distal matrix." The proximal matrix continues proximally and laterally to form the lateral matrix horn. The nail surgeon should be cognizant that the lateral matrix horn may be extensive.

The lunula is an opaque, grayish white, half-moon–shaped structure that extends beyond the distal limit of the PNF. The lunula is usually seen through the transparent nail plate, especially on the thumbs and great toes, as the visible distal component of the nail matrix.[1, 4, 5, 11] The distal margin of the lunula must always be preserved during nail surgery if the normal shape of the nail is to be maintained[1, 13, 29] An active granular layer typically found in the PNF is missing from the nail matrix; therefore, keratohyaline granules cannot be found in the matrix. The basal cells of the matrix actively participate in the process of differentiation and keratinization to eventually produce the dead horny product, the nail plate.

Several reasons exist why the nail surgeon must attempt to leave the structural and functional boundaries of the nail matrix intact when performing nail surgery; some of the reasons include the following:

  • The matrix is the center of nail formation and the source of the nail plate.

  • Nail growth is a direct function of the rate of turnover of matrix cells.[1]

  • Nail thickness is directly related to the length or the size of the nail matrix.[14]

  • The shape of the distal border of the lunula determines the shape of the nail. If this border is convex, the distal free edge of the plate will also be convex.

Disruption of any of these components of the nail matrix can result in scarring and onychodystrophy of the evolving nail plate. The most common indication for partial or complete destruction of the matrix is a recurring problem of ingrown nails recalcitrant to conventional therapies. The healthy matrix synthesizes a complete fingernail plate on an average of every 6 months.[1, 2, 22]

Nail bed and dermis

The nail bed is the sterile component of the nail unit and the primary site of nail keratinization.[4, 5] The nail bed extends from the distal lunula to the point of origin of the hyponychium. It shares similar boundaries with the nail plate, with the lunula marking the proximal border of the nail bed, with the lateral folds marking the lateral border, and with the hyponychium marking the distal border.

The epidermis of the nail bed is relatively thin, with a dimensional thickness of only 1-2 cells.[4, 5] The epidermal surface of the bed has parallel longitudinal ridges that interlock with similar folds on the ventral surface of the nail plate.[1, 3, 4, 5, 29] The ridges securely bind the nail plate to the nail bed, allowing a firm adhesion between the 2 structures. The area marking the point at which living cells become keratinized and continue to become dead horny cells of the nail plate is abrupt.[4, 5]

The nail bed is a highly vascular structure that lacks an underlying subcutaneous layer of adipose tissue. As a result, nothing separates the dermis from the periosteum of the distal phalanx. The lack of this layer becomes apparent when one is confronted with aggressive tumors of the nail because such tumors may easily extend to involve the underlying bone.

The connective tissue of the dermis, the dermal collagen, contains a balanced mixture of lymphatics, blood vessels, and elastic fibers. The dermis also has a wealth of glomus bodies and a rich capillary network longitudinally oriented with the parallel ridges. Splinter hemorrhages of the nail plate form when a small amount of blood leaks from the capillary bed into one of these folds and becomes trapped by the nail plate.[2] Melanocytes are not found in the nail bed, although they are present in significant numbers in the matrix.

Vascular and nervous supply

An abundantly rich arterial and capillary vascular network supplies the nail unit. The ulnar and posterior tibial arteries divide into the proper palmar and plantar digital arteries, respectively. The two digital arteries, which occupy the lateral and medial aspects of the digit, form a cruciate anastomosis at the level of the deep dermis in the ventral pulp space. Upon anastomosing on the volar aspect of the terminal phalanx, the two arteries contribute branches to a superficial arcade and the underlying phalangeal periosteum.[29] The superficial arterial arcade, which also receives a contribution from a vessel coursing dorsally over the DIP joint, supplies the PNF, including the capillary loops of the nail fold and the nail matrix.

The digital arteries continue around the waist of the terminal phalanx and onto the dorsal surface where they divide near the DIP joint to form the dorsal and ventral arches supplying the nail bed and the nail matrix. The dorsal arch courses dorsally over the DIP joint where it terminates in an anastomosis with the proximal arch to supply the matrix and the PNF. The capillary loop system in the PNF is derived from the anastomosis between the two arches.[1, 8, 29] Therefore, perfusion of the nail matrix comes from two arterial systems: the superficial arcade and the proximal arcade. Anatomically, the superficial arcade sits at the base of the PNF, while the proximal arcade lies deep to the matrix.[29] The ventral or distal branch supplies the remainder of the nail unit, specifically its most distal aspect, including the fingertips.

An accessory blood supply that is separate from the main blood supply in the pulp space also exists. This accessory system is important in providing adequate perfusion of the nail unit for normal nail growth when the primary vasculature is compromised by disease, which sometimes occurs in scleroderma or infection.[3]

Specialized neurovascular structures called glomus bodies are widely distributed throughout the arterial and deep venous circulation. These oval bodies are encapsulated, consisting of tortuous blood vessels and a neural supply of mostly cholinergic nerves.[3, 8] The glomus bodies form an extensive arteriovenous (AV) anastomotic network, which functions in modulating the thermoregulatory response of the nail unit. Under circumstances where the nail is exposed to cold temperatures, the glomus bodies enhance blood flow to the nail complex by dilating and shunting blood through their complex AV anastomotic systems to prevent ischemia.[3, 4, 5, 11, 33]

The nail apparatus is also richly innervated by a complex neural system allowing tactile sensitivity and sensory discrimination. Anatomically, the laterally positioned digital nerves and their divisions nearly parallel the vascular supply to the nail unit. Specifically, there are two dorsal and two volar digital nerves, and the first through fifth digits are innervated by the dorsal nerves, whereas the second through fourth digits are innervated by the volar nerves.

Contraindications

Relative contraindications to performing surgery in the nail unit include the presence of established peripheral vascular disease, collagen vascular disease, diabetes mellitus, and disorders of hemostasis. Patients presenting with acute infection or inflammation of the nail unit, including the surrounding paronychial tissues, are considered to have relative contraindications to nail surgery. When possible, surgery in these patients should be postponed until the acute event has resolved.

When administering anesthetic for nail surgery, the use of epinephrine should be avoided or cautiously used in patients with a history of thrombotic or vasospastic disease such as thromboangiitis obliterans, Raynaud disease/phenomenon, or severe peripheral vascular disease.[34, 35] Epinephrine has vasoconstricting properties, and it has been associated with necrosis and poor wound healing of tissues. However, these complications appear to be mostly theoretical and have rarely been noted to occur in practice.

Wilhelmi et al performed an extensive review of the medical literature and found no reports of epinephrine as a primary cause of ischemic necrosis or finger gangrene when appropriately mixed with lidocaine for digital block. The authors confirmed this finding when they performed 23 digital blocks with 1% lidocaine with 1:100,000 and 1:200,000 epinephrine. They recommend the use of epinephrine as an adjunctive component to help augment the effect of the local anesthetic, decreasing the total amount of anesthetic required and lowering the risk of toxicity.

Several studies have proposed that epinephrine can be used safely in the digits.[36] Epinephrine is also beneficial in reducing blood loss at the surgical site because of its hemostatic properties. However, Wilhelmi et al caution that the maximum dose of epinephrine used in healthy individuals should not exceed 1 mg. Also, epinephrine should be cautiously administered in patients presenting with pheochromocytoma, severe hypertension, hyperthyroidism, and heart disease.[37]

Sylaidis and Logan determined that digital blocks of 2% lidocaine with 1:80,000 epinephrine were safe, although intense local vasoconstriction was noted at the injection site. In their prospective study involving 100 patients, they observed the effect of 2% lidocaine mixed with 1:80,000 epinephrine on several variables of digital arterial perfusion. No ischemic necrosis of the digit was reported after the application of a digital block. The fingers remained well perfused despite the apparent vasoconstriction at the injection site.[38] Therefore, epinephrine can be a safe and valuable adjunct when appropriately mixed with lidocaine to perform a digital block. In the event that ischemia does occur, it can be reversed with phentolamine injection or nitroglycerin ointment.[34]

During nail surgery, the application of a tourniquet at the base of the digit allows the surgeon to operate in a bloodless surgical field.[39] However, to avoid complications such as vascular compromise of the extremity, the use of a tourniquet for more than 15 minutes should be avoided. Optimal hemostasis is achieved when the tourniquet is applied for a maximum period of 15 minutes during the most critical part of the surgery.

 

Workup

Diagnostic Procedures

Biopsy of the nail unit

The nail is made up of many individual components. Each has a particular anatomical and physiologic function and characteristic. Therefore, appropriately, each of these components is affected by specific disease processes. Several specific indications for performing biopsy on the nail unit exist. Overall, the primary purpose of nail biopsy is to help the clinician establish or confirm a definitive diagnosis and, thus, initiate early effective treatment to prevent further nail destruction. Biopsy of the nail unit should be avoided if possible in patients with known peripheral vascular disease, collagen vascular disease, or diabetes mellitus and in those who are immunocompromised.

Biopsy of the nail unit may be performed for the following indications:

  • To determine the pathogenicity of fungal organisms in recalcitrant fungal infection[40]

  • To establish the presence of a psoriatic nail versus a mycotic nail or other underlying nail disease causing long-standing nail plate deformity (eg, onycholysis)[41]

  • To identify and treat the cause of pain (eg, ingrown nails, tumors)

  • To facilitate the early diagnosis of longitudinal pigmented streaks; malignant subungual and periungual tumors; and benign tumors, such as subungual exostosis of the nail unit[8]

  • To differentiate an inflammatory etiology (eg, lichen planus) from an infectious etiology involving the nail unit

  • To obtain diagnostic and prognostic information in presentations of isolated nail pathology when routine diagnostic procedures are unsuccessful[42]

To obtain an acceptable tissue specimen for pathologic evaluation and to ensure optimal cosmetic success when performing a biopsy of the nail apparatus, several issues, described below, should be considered.[13, 43]

Before proceeding with nail biopsy, the nail surgeon must determine the procedure that will be most beneficial to the patient, while offering minimal risks and complications.

The nail surgeon should perform a biopsy on the smallest amount of nail tissue necessary to make a diagnosis, leaving the healthy tissue undisturbed.

When possible, biopsy of the nail bed should be performed, and the anatomical area marking the nail matrix should be avoided.

Biopsy samples of the nail bed should be longitudinal, while samples of the nail matrix, when necessary, should be transverse or horizontal. Depending on the location of the pathology, longitudinal biopsy samples are best obtained at the lateral margin of the nail where the risk of scarring is reduced.

All incisions should be extended to the underlying bony phalanx. Excisions should be fusiform, approaching a width of less than 3 mm. After successful biopsy, if the area excised is more than 2 mm, it should be carefully undermined and closed with nylon sutures.

Anesthesia must be properly administered before performing any invasive procedure on the nail unit. After biopsy, the specimen should be placed in periodic acid-Schiff (PAS) or Gomori methenamine-silver stain. In onychomycosis, a few fungal elements may not be seen if the specimen is stained with only hematoxylin and eosin (H&E).[2]

Biopsy of the nail plate

Biopsy of the nail plate and the hyponychium is performed to help diagnose mycotic nail dystrophies, such as onychomycosis and other dermatoses affecting the nail plate. Biopsy of the nail plate usually involves removing a piece of the distal plate along with a portion of the underlying hyponychium by using scissors, a bone rongeur, or a scalpel. Alternatively, in cases where mycotic disease is suspected to extend beyond the distal nail plate, a 3- or 4-mm trephine punch may be used.[8] At the target site, the punch is applied with moderate pressure against the nail plate, passing through the nail bed until it contacts the periosteum. The punch is withdrawn, and the specimen is removed with fine scissors for histopathologic examination.

A technique that can be used to rule out onychomycosis is the noninvasive keratin biopsy. This biopsy technique has the added benefit of helping differentiate between hemosiderin versus melanic pigment in cases in which the nail has black or brown discoloration.[39]

The 2-punch technique is used when both the nail plate and the nail bed are involved in a specific disease. In this technique, the larger punch is used first to remove a circular defect in the nail plate. This punch is followed by a smaller punch that is advanced through the defect created in the nail plate to the nail bed underneath.[8, 14] When the nail plate is the primary target for sampling, a quick punch biopsy can be performed without anesthesia. Some surgeons prefer disposable punches because of their sharpness and ease of penetration. After biopsy, hemostasis is achieved by the direct application of pressure and the placement of Oxycel or oxidized cellulose at the biopsy site.

Biopsy of the nail bed

Biopsy of the nail bed may be performed to facilitate the accurate diagnosis of a tumor, to diagnose an unknown isolated lesion in the nail bed, or to diagnose a disease[8, 14] Multiple ways to perform biopsy of the nail bed exist.

A standard punch biopsy of the nail bed is one of the most commonly performed surgical procedures on the nail unit.[2] Before biopsy of the nail bed, radiography of the involved digit is indicated if extensive tissue distortion is present or if the type of pathology is questionable.[29]

When the nail bed is sampled, a partial avulsion of the distal half of the plate may be performed, or a complete avulsion may be performed to remove the entire nail plate, allowing direct visualization of the disease process involving the underlying nail bed. Avulsion is followed by 3-mm punch biopsy of the nail bed extending to the periosteum. Fine iris scissors are used to release the tissue specimen. The surgeon may choose to perform a longitudinal elliptical excision of the nail bed, advancing fully to the periosteum to remove a narrow wedge of tissue for sampling. Proximal avulsion of the nail plate is performed when a glomus tumor is suspected. In cases where nail avulsion is not performed, thinning of the nail plate may be required before obtaining tissue from the nail bed.

Alternatively, a decision might be made to leave the nail plate intact. The double punch technique is performed to obtain tissue from the nail bed. First, a larger 4- or 6-mm punch is applied to remove a circular defect in the nail plate.[8, 14, 44] A second smaller 3-mm punch is used to obtain a specimen of the nail bed through the nail plate defect created by the first larger punch.[8, 14, 44]

In situations where PAS staining is indicated to detect hyphal elements for diagnosing chronic onychomycosis from other nail dystrophies, a punch through the nail plate into the distal nail bed and the hyponychium is useful.[13]

If a standard punch biopsy of 3 mm or smaller is used, the surgical site does not need to be closed, and it is allowed to heal by secondary intention. Granulation tissue develops shortly after biopsy.

For longitudinal excisions larger than 2 mm, the surgical site should be undermined first,[14] especially if the nail bed epithelium is greatly bound down. This step is followed by the placement of 4-0 or 5-0 Dacron or nylon sutures. After biopsy, to achieve hemostasis, 35% aluminum chloride in 50% isopropyl alcohol (Monsel solution) is applied to the site. Oxycel or absorbable collagen may also be used as an aid to hemostasis. Excellent healing with minimal nail scarring and distortion is normal after biopsy of the nail bed. Occasionally, nail splitting at the sampling site may occur.

Biopsy of the nail matrix

The primary indications for biopsy of the nail matrix include (1) diagnosing tumors originating in the matrix; (2) determining the cause of full length nail plate malformations and nail dystrophies arising from a matrix abnormality; and (3) establishing a diagnosis of melanonychia striata versus malignancy (eg, melanoma) in presentations of longitudinal, dark pigmented streaks in the nail plate.[1, 13, 32, 45, 46] Although junctional nevi in the matrix most often account for the brown- or black-pigmented streaks found in the nail plate, melanoma involving the matrix is an important part of the differential diagnosis and must be excluded by matrix biopsy.

When biopsy of the nail matrix is performed, the normal curvature of the distal matrix or lunula must be maintained to avoid distortion and scarring of the nail plate.[1, 8, 13] Additionally, all biopsy samples of the nail matrix should be transverse rather than longitudinal, as samples taken from the nail bed.

Before biopsy of the nail matrix is performed, the extremity is cleansed with derma surgical soap, followed by a 1:1000 aqueous solution of Zephiran. A sterile surgical field must be maintained throughout the procedure.

In presentations with suspicious pigmented lesions involving the matrix, a mark should be placed on the PNF to identify where the pigmented lesion was first found.

Anesthetic is administered through a digital or local block, and a wide Penrose drain is used for hemostasis.

The nail plate may be completely avulsed, but complete avulsion is not always indicated, especially if a punch 3 mm or smaller is used. A partial avulsion of the proximal one third of the plate may be performed, leaving the distal two thirds of the nail plate intact (eg, when a focal abnormality is confined to the proximal one third of the matrix). Zaias recommends performing a complete nail avulsion to avoid the throbbing pain that develops from edema occurring in the traumatized area in partial avulsions. After avulsion, the matrix is fully exposed, and the lesion is identified.

At this point, biopsy of the matrix can be completed in 1 of 2 ways. All or part of the lesion may be removed with a 3-mm trephine punch biopsy or by a crescent-shaped (transverse) elliptical wedge excision, both extending down to the bony phalanx. The distal edge of the ellipse should be parallel to the curvilinear shape of the distal matrix. Maintaining the integrity of the distal lunula border minimizes the formation of a new dystrophic nail plate.[1, 8, 13, 14]

In proximal nail plate avulsions performed for matrix biopsy, after standard preparation, a Freer elevator is inserted beneath the PNF disrupting the association between the cuticle and the nail plate. A small incision is made at the junction of the PNF and the LNFs on both sides of the digit. The incision is extended posteriorly and approximately 5 mm proximally and laterally toward the DIP joint. The PNF and its free edges are reflected with skin hooks, allowing full exposure of the matrix. At this juncture, the matrix may be sampled by performing 3-mm trephine punch biopsy, incisional biopsy, or elliptical wedge excision. When complete exposure of the matrix is required, the nail plate may be partially or completely avulsed prior to biopsy.

A mosquito hemostat is used to free the proximal one third of the nail plate from its attachments at the proximal and lateral nail walls. The blunted hemostat is used to separate the proximal plate and the associated nail root from the underlying nail bed. Fine iris scissors are used to dissect the proximal one third of the nail plate from the distal two thirds, allowing the proximal nail plate to be released. Usually, bleeding is controlled with direct pressure. Some permanent scarring or defect is expected to form in the nail plate, especially when biopsy samples larger than 3 mm are obtained from the distal matrix.[47, 48] However, the defect is barely noticeable if the matrix is appropriately sampled.

Transverse biopsy of the nail matrix may change the thickness of the nail plate, producing a thinner plate only if the proximal matrix is undisturbed and no fissures are present.[8] Distal onycholysis and an abnormal curvature of the distal free edge of the nail plate may result if the convex border of the distal lunula is accidentally bisected.

When closing the surgical defect created in the matrix, several guidelines should be followed to prevent long-term nail disfigurement and dysfunction. After biopsy, the matrix is sensitive to tension.[1] Therefore, the defect in the matrix should first be carefully undermined and approximated to avoid tension during closure.[1, 8] The surgical site is closed with interrupted absorbable 4-0 or 5-0 Dexon sutures placed superficially. Sutures should not be buried deeply into the dermis because it is here that the matrix epithelium gives rise to the nail plate. At times, the surgical defect is allowed to heal by secondary intention. When sutures are appropriately threaded into the wound, they are seen emerging from the matrix epithelium into the newly formed plate as the nail plate grows distally.[8]

If the PNF is retracted, it is placed into its original position, and the incisions are closed with interrupted 5-0 nylon sutures. Xeroform gauze is usually inserted between the matrix and the ventral surface of the PNF to avoid the subsequent formation of adhesions. Pterygium results when the PNF and the open matrix adhere to each other and form a scar. The outcome is a new nail that is onycholytic. When compared with fusiform biopsies and excisions of the matrix, crescentic excisions are less favored because they may provide samples of inadequate width.[8] In conclusion, the likelihood of eventual nail distortion is decreased if the defect is properly sutured.

Haneke recommends a practical approach to the management of large pigmented lesions of the nail unit instead of total nail avulsion in all cases. He suggests performing a shave biopsy of the complete pigmented layer, removing the upper layers of the matrical epidermis. If the lesion is found to be malignant after a pathology evaluation, excision of the entire nail apparatus is required. Alternatively, if the lesion is found to be benign, the patient is spared the complication of significant nail dystrophy.[49]

En bloc biopsy of the nail complex

The lateral longitudinal en block biopsy of the nail is performed to sample the PNFs and the LNFs, the nail plate, the nail bed, the nail matrix, and the hyponychium. This procedure should be reserved for cases suggestive of longitudinal melanonychia, for dystrophy present throughout the entire length of the nail, and for determining the extent of involvement of the nail complex by malignancy (eg, to exclude localized vs invasive SCC or basal cell carcinoma of the nail unit).[23, 45, 47]

Lateral longitudinal biopsy of the nail complex is also performed for the purpose of surgically correcting a lesion in the lunula–nail bed area producing onycholysis and for ablation of the lateral matrix in the treatment of an ingrown nail.[1, 23, 50, 51] Standard preparation includes performing a digital block and soaking the extremity in a warm antiseptic solution, followed by scrubbing of the area beneath the distal edge of the nail plate.

If biopsy of the nail plate is not necessary, a complete avulsion is performed. If the surgeon desires to sample the nail plate, nail avulsion is performed on both sides of the area selected for biopsy. Partial hemiavulsion is performed with a mosquito hemostat or, preferably, a Freer elevator, the latter being less traumatizing to the nail. First, the PNF is separated from its attachments. Then, the nail plate is separated from the nail bed, the nail matrix, and the hyponychium.

En bloc excisional elliptical biopsy is performed by using a scalpel and curved iris scissors. The incision should be parallel to the lateral edge of the nail plate, and it must be advanced to the periosteum to ensure that a full-thickness sample of the matrix is included in the specimen. A rectangular block of tissue about 2-3 mm in diameter that contains the nail bed, the nail matrix, the PNF, and the hyponychium, with or without the nail plate, is removed. After biopsy, the edges of the lunula must be carefully approximated and sutured in a manner that recapitulates its original shape. A new LNF is formed by joining the remaining LNF to the lateral nail plate. All suturing should be directed away from the incision site to reduce tension and to provide better maneuverability; 3-0 or 4-0 nylon sutures should be used. The first suture is placed into the LNF, followed by the nail bed, and then the nail plate. The suture knot is tied on the nail plate away from the incision.

In some cases, the biopsy site is allowed to heal by secondary intention. After this procedure, the nail's width is permanently reduced, and the angle between the PNF and the LNF becomes more acute. Onycholysis rarely develops after lateral longitudinal nail biopsy. Removing the specimen from the lateral margin of the nail reduces the risk of functional impairment and nail dystrophy. Central longitudinal nail biopsies are associated with significant scarring, permanent fissuring, and poor cosmetic outcome.[31, 47, 48] If the only choice is to perform a midline biopsy, scarring is reduced if the PNF is reflected.

En bloc excision of the PNF

The PNF may be completely excised to assist in diagnosis and treatment of recalcitrant chronic paronychia, refractory myxoid cysts, collagen vascular disorders, and benign and malignant tumors.[13, 48]

Separation of the nail plate from the cuticle is accomplished with a dental spatula or Freer elevator. The elevator or spatula is advanced until it reaches the proximal nail groove. The PNF is excised with a scalpel by making a crescent-shaped excision 3 mm beyond the DIP joint, starting at the junction of the PNF and the LNF and ending at the proximal-lateral fold junction on the contralateral side. When biopsy of the PNF is performed, the matrix may be shielded from accidental incision by placing a Freer elevator between the PNF and the matrix. Healing occurs by secondary intention.

Biopsy of the PNF and the LNF

Incisional biopsy is the preferred surgical approach when sampling the PNF or the LNF for diagnostic purposes.[13] The most common indication for biopsy of the PNF is the presence of focal disease, such as chronic paronychia, focal tumor, myxoid cyst, collagen vascular disease, or dermatosis.[8, 23] Biopsy of the PNF may be completed in one of three ways.

One technique involves performing a 2-mm punch biopsy that reaches and samples the dorsal surface of the nail plate but leaves the distal margin of the PNF intact. When a larger amount of tissue is required for sampling, a transverse incisional biopsy of the PNF is performed. The incision extends to the periosteum and is parallel to the relaxed skin tension lines. This technique provides adequate tissue for histology and staining (eg, PAS, acid-fast, H&E). It also permits easy primary closure without undermining the wound, while maintaining the anatomy of the nail fold. Areas that should be avoided during the incision are the distal free margin of the nail to prevent notched scarring and the extensor digitorum tendon near the DIP joint.[13] Suturing is performed by using 4-0 or 5-0 Prolene sutures. Sutures are removed in 1 week.

When surface biopsy is indicated, a razor blade is used (shave biopsy). The blade is first split into two parts, and the half blade is used in a flat plane to obtain a sample of the PNF tissue at the desired depth.[13, 48] Hemostasis at the surgical site is achieved with Monsel solution and direct pressure. The biopsy site usually heals by secondary intention with negligible scarring. Biopsy of the LNF is most commonly performed in presentations of hyperkeratotic plaques previously treated as warts or fungal infection.[13]

Excisional biopsy is performed to exclude Bowen disease or SCC. This procedure is also used to excise the hypertrophic tissue occurring in onychocryptosis. Except for a longitudinally directed fusiform excision, biopsy of the LNF follows the same surgical approach as that used on the PNF. Frequently, the lateral sulcus and the ventral nail plate may harbor pathology requiring paring back of the nail plate to allow full visualization of all areas.

All biopsies of the nail bed should extend to the periosteum. When suturing, the suture is first passed through the LNF skin, then across the nail bed, and finally through the nail plate. In all biopsies, a digital block is performed, and a tourniquet is used for hemostasis.

Imaging Studies

Ultra‒high-frequency ultrasound

More recently, the development of ultra‒high-frequency ultrasound introduces new diagnostic, noninvasive imaging modalities. The main applications include assessment of skin layers and hair follicles, as well as the nail unit.[52] This has the potential to delineate anatomy preoperatively, differentiate solid and cystic lesions,[53] and aid in therapeutic decisions when clinical examination is equivocal. However, there is still a need for comprehensive validation studies and assessment of long-term outcomes based on the ultrasound examinations.

 

Treatment

Approach Considerations

Nail treatment and surgical options must be individualized based on the nail condition, extent of disease, type of organism, and medical comorbidities. Patients with factors that predispose to infection, such as uncontrolled diabetes, prior methicillin-resistant Staphylococcus aureus infection, and immunosuppression, may require prophylactic antibiotics. Other factors to consider prior to determining an appropriate treatment algorithm include patient preference, concomitant medications, cost, and insurance coverage.

Surgical Therapy

Nail avulsion

Nail avulsion is the most common surgical procedure performed on the nail unit. It is the excision of the body of the nail plate from its primary attachments, the nail bed ventrally and the PNF dorsally. Avulsion of the nail plate may be initially performed to allow full exposure of the nail matrix before chemical or surgical matricectomy.[13, 54, 55] Other indications for performing nail avulsion are to treat recalcitrant onychocryptosis; to excise tumors of the nail unit; to allow full examination and exploration of the nail bed, the nail matrix, the PNF and the LNF, and the nail grooves for the presence of pathology; or to use as a preliminary step before performing biopsy on the nail bed and the nail matrix.

Avulsion of the nail plate is frequently used as a therapeutic adjunct in long-standing fungal infections of the nail, such as chronic onychomycosis, and in acute bacterial infections.[13, 56] In traumatic nail injuries, avulsion may be used to evaluate the stability of the nail bed or to release a subungual hematoma after failed puncture aspiration.

Paring the nail plate is the process of taking off pieces of the nail in a transverse or longitudinal fashion to fully observe an involved area on the nail bed.[13] In the case of verrucae, nail paring may be performed to determine the extent of disease involvement of the nail plate and the underlying nail bed.

The two primary methods for performing nail avulsion are distal avulsion[2, 14, 48, 57] and proximal avulsion.[1, 8, 14, 58] A third method, chemical avulsion with urea paste, is a nonsurgical avulsion technique that may be performed. A partial or complete nail avulsion can be performed, depending on location and extent of disease. Surgical nail avulsion is not a definitive cure in cases of nail dystrophy caused by onychocryptosis, nail matrix disease,[23] or extensive nail bed pathology (eg, SCC).

Depending on the indication, the nail surgeon must exercise restraint in the decision to perform nail avulsion because cosmetic and functional outcomes should be considered. A distorted curvature of the newly formed nail plate and an elongated, thickened nail due to hypertrophy of the nail plate and the nail matrix are complications associated with multiple or repeated avulsion procedures.

Before avulsion, anesthesia of the digit is achieved through a digital block performed with 1% lidocaine. A Penrose drain secured with a hemostat clamp is used for hemostasis. Any of the following 3 blunted instruments may be used to separate the nail plate from its attachments: the mosquito hemostat, the Freer septum elevator, or the dental spatula. In distal nail avulsion, the instrument is introduced under the distal free edge of the nail plate to separate the nail plate from the underlying nail bed hyponychium on its ventral surface. All attempts at separation are directed proximally toward the matrix, with significant resistance occurring until the matrix is reached. When the matrix is contacted, the surgeon usually experiences less resistance and might feel a laxity because of a weaker attachment. After reaching the matrix, the elevator is reinserted with several longitudinal forward and backward strokes performed side by side until the nail bed is completely freed from the overlying nail plate.

To free the nail plate from its association with the PNF and the cuticle, the Freer elevator is inserted under the PNF in the proximal nail groove between the eponychium and the nail plate. Aggressively inserting the instrument into the proximal nail groove causes unnecessary injury and postoperative morbidity, and it should be avoided. Next, the hemostat clamp is used to gently secure and remove the nail plate. If the hemostat blade is used, the serrated, toothed portion of the blade must be oriented to lie directly against the undersurface of the plate and the PNF.

Proximal nail avulsion is attempted when creating a cleavage plane between the nail plate and the nail bed distally is impossible because of the presence of distal nail dystrophy, which prevents access to the distal free edge of the nail plate. This presentation may be seen in distal subungual onychomycosis.[8, 57, 59] First, the Freer elevator is inserted beneath the cuticle in the proximal groove to separate the PNF from the nail plate. Then, it is repositioned to allow its concave surface to match the curved contour of the ventral surface of the nail plate.[23] The instrument is advanced until it finally reaches the distal edge of the nail plate. A hemostat is used to gently remove the nail plate.

The use of urea ointment to debride and avulse dystrophic nails has been applied in the treatment of onychomycosis, onychogryphosis, psoriasis, and candidal and bacterial infections.[60, 61, 62] Nail plates that are significantly dystrophic appear to respond better to avulsion with urea paste. The benefits of performing nonsurgical nail avulsion with urea ointment include pain relief; a low risk of infection, hemorrhage (ie, bloodless procedure), and other morbidity; a quick improvement after avulsion; and the absence of pain during and after treatment.[60]

Nail avulsion with urea is ideal for the treatment of symptomatic dystrophic nails in patients with diabetic neuropathy, vascular disease, or immunosuppression.[60] A disadvantage of urea avulsion is the required length of application and the potential irritation that may result from the acidity of urea. Urea acts by dissolving the bond between the nail bed and the nail plate, and it also softens the nail plate. Urea ointment paste is formulated to include 40% urea, 5% white beeswax or paraffin, 20% anhydrous lanolin, and 35% white petrolatum.[60, 61] Alternatively, Ureacin-40 ointment is an over-the-counter commercial product that is ready made and can be used as a substitute.

Prior to the application of urea, the paronychial area is protected with adhesive tape to prevent chemical irritation of the soft tissues. Urea ointment is liberally applied to the nail plate, and an adhesive felt (eg, moleskin) or a waterproof, stretchable, hypoallergenic tape (eg, Blenderm) is used to create a well around the treated thickened nail to hold the paste.[62] The patient is instructed to keep the nail occluded and to avoid wetting the treated area. After 1 week of occlusion, a blunt dissection is performed to facilitate removal of the dystrophic nail by using a nail elevator and a nail clipper, while leaving the underlying normal nail intact. The avulsion procedure is painless, thus negating the need for anesthesia. The avulsed area is treated with a topical antifungal agent. When necessary, this treatment is complemented with oral antifungals until the new nail is well formed.

Gross thickening of the nail without significant nail dystrophy may be the etiology of a poor response to urea treatment.[8, 60] In this case, gentle abrasion of the nail surface may be tried to help improve penetration of the chemical agent. Contact of the urea-treated nail with water and poor occlusion by the dressing are other causes of treatment failure. When minimally dystrophic nails are being avulsed, a combination of 20% urea and 10% salicylic acid ointment under a 2-week occlusion may be tried.[8] Onychogryphosis commonly leads to nonreversible nail dystrophy. Urea avulsion is indicated in the treatment of this condition to provide pain relief, and it may be performed twice a year for this purpose.

Matricectomy

The nail matrix is the germinative epithelium that forms the nail plate by means of the continuous differentiation of its basal cells. Matricectomy is the process of surgically, chemically, or electrically ablating or destroying the nail matrix. Complete excision of the viable nail matrix results in loss of the nail plate. Therefore, a new nail plate cannot be regenerated.

Multiple indications for performing matricectomy exist, the most common being a diagnosis of recalcitrant recurrent onychocryptosis or ingrown nails.[9, 14, 44, 63] In this and other debilitating nail conditions, matricectomy should only be considered after all conventional therapies, including temporary partial or complete nail avulsion, have been unsuccessful and the condition remains refractory to treatment. Other indications for performing matricectomy include chronic nail dystrophies, such as onychauxis, onychogryphosis, onycholysis, psoriatic nail, symptomatic onychomycosis that is unresponsive to aggressive antifungal therapy, and painful nail conditions, including pincer nail deformity.[13, 14, 43, 64] For most of these conditions, matricectomy is the definitive cure.

When a decision is made to perform matricectomy, a complete or partial procedure can be completed. Most commonly, a partial matricectomy (the removal of the diseased portion of the nail matrix with an attempt to preserve the central portion of the nail plate) is preferred because preservation of the normal structure and function of the nail plate is possible.

Total matricectomy permanently destroys the ability of the nail complex to produce a nail plate.[23] Complete matricectomy is reserved for cases of chronic or severe nail dystrophy, especially when the condition has become refractory to multiple attempted treatments. Some examples of chronic nail dystrophies that may require total matricectomy include, but are not limited to, onychauxis, onychogryphosis, onychomycosis, psoriasis, and pincer nail deformity.[9, 64] Partial matricectomies are especially useful in the management of persistent onycholysis and onychocryptosis. Some surgeons prefer bilateral partial matricectomy, even when the contralateral side may not yet be affected by onychocryptosis. This procedure allows the nail plate to maintain its function and aesthetics.[9, 14]

Onycholysis[1, 8, 11] is the separation of the nail plate from the nail bed distally and laterally. When onycholysis extends to the matrix, the detachment is considered complete.[8] In onycholysis, the nail color may become grayish white from air trapped under the nail.

In onycholysis associated with psoriasis, a yellow border may be present between the healthy pink nail and the separated white portion of the nail plate.[8] Onychomycosis and trauma are the 2 major causes of onycholysis of the toenail. Other causes of onycholysis include local trauma; fungal, viral (wart), or bacterial infection; inflammatory disease (eg, lichen planus); alopecia areata; psoralen plus ultraviolet A (PUVA); certain antibiotics (eg, tetracycline); some chemotherapeutic agents (ie, 5-fluorouracil, doxorubicin, bleomycin); and congenital disease as in congenital paronychial infection and partial hereditary onycholysis.[8, 65]

Onycholysis is usually painless, but the patient might complain of mild pain during the early inflammatory period.[8] Before matricectomy, the preoperative evaluation should include a medical history and physical examination to exclude patients with documented small and large vessel occlusive disease (eg, atherosclerosis, diabetes mellitus, collagen vascular disease) in whom, because of delayed healing, this type of surgery is considered to be relatively contraindicated. Patients presenting with claudication, absent distal pulses on palpation and Doppler examination, poor capillary refill, poor wound healing, or low oxygen saturation should be excluded.[9] Matricectomy should be deferred until all acute infection of the digit and paronychial tissues has resolved.

Matricectomy can be performed by using surgical, chemical, or electrical modalities. Ablative matricectomy involves the use of chemocautery, electrocautery, or laser[9] to destroy the nail matrix. Excisional matricectomy uses cold steel surgery, cutting electrosurgery, or cutting laser[9] to remove the matrix.

Conservative treatment to correct an ingrown nail includes removing the nail spicule (the inciting cause), trimming the nail transversely to promote forward growth, and daily packing of nonabsorbent cotton under the involved area of the nail plate to allow the nail to grow out straight. A partial or complete nail avulsion may be curative, but, in some cases, it only serves as a temporary measure.

Surgical intervention is indicated when conservative measures fail. In preparation for surgical extirpation of the matrix, all nail spicules are removed by curettage. Hypertrophied granulation tissue can be reduced with an intralesional corticosteroid injection of triamcinolone acetonide, high-potency steroid preparations, cauterization, or excision. Removal of granulation tissue frees the previously fixed nail plate, allowing the plate to be elevated out of the LNF groove.

Surgical resection of the LNF, lateral nail plate, hyponychium, nail bed, and nail matrix is scheduled at 4 weeks after curettage and excision of the granulation tissue. Essentially, the entire lateral nail-forming unit is removed. Two important issues must be considered before performing matricectomy: (1) All excisions must extend to the periosteum with caution to avoid the insertion of the extensor tendon on the distal phalanx. (2) No remnant of the lateral matrix horn must be left behind to prevent recurrence of nail spicules.[9, 13]

In the surgical management of onychocryptosis, several procedures and techniques are available to the nail surgeon, with each technique having benefits and disadvantages. When performing a partial matricectomy, the digit is first prepared in a sterile environment (iodine or chlorhexidine scrub may be used), and anesthetic is administered through a digital block. A 3/8-inch Penrose drain is used as a tourniquet to provide hemostasis. Some surgeons may prefer an exsanguinating tourniquet to maintain a bloodless field[9, 44]

The area to be excised is outlined with a surgical pen, and a partial nail avulsion is performed. A nail splitter is used to cut the nail plate longitudinally, consisting of approximately one fourth of the distance from the lateral nail wall. After cutting the nail plate, a nail elevator or a straight hemostat is applied to separate the nail from its attachments at the PNF, the nail bed, and the matrix. The laterally avulsed nail is grasped and rotated out toward the disease-free nail to prevent embedding of nail spicules into the LNF. The PNF is reflected back to allow full visualization of the matrix.

After avulsion, a scalpel blade is used to make 2 longitudinal incisions, measuring 4 mm in width, beginning at the distal edge of the nail to include the hyponychium and advancing proximally. The nail bed, the nail matrix, and the lateral aspect of the PNF are excised. The incision also extends to include the LNF and the lateral matrix horn in the lateral nail groove. The surgical sample is a wedge of tissue containing the nail-producing components of the nail unit. Fine scissors are used to remove the tissue sample. After obtaining the sample, the PNF is repositioned to its original anatomical site. Hemostasis is achieved with electrocoagulation, Monsel solution, or aluminum chloride solution. The wound may be allowed to heal by secondary intention. Alternatively, the wound may be closed by passing sutures through the nail plate and the LNF.

When dressing the wound, the lateral nail groove is packed with iodoform or petroleum jelly gauze. A nonadherent dressing (eg, Telfa) is applied, followed by the placement of a bulky dressing or cling that is secured with elastic tape. Elastoplast may be used. At 24-48 hours after the initial dressing is applied, the wound is soaked in warm water, and the dressing is removed and changed. After surgery, the nail plate remains functional and is cosmetically acceptable. As a result of partial excision of the nail matrix, the newly formed nail plate is narrower because of a decreased width.

In total matricectomy, the entire nail plate is avulsed. A scalpel is used to make 2 incisions oriented proximally and laterally; these incisions extend to the PNF and the LNF. The PNF is dorsally reflected to allow full exposure of the nail matrix, including the lateral matrix horn area. During matricectomy, the first incision is made about 1 mm distally to the distal border of the lunula and is carried 4-5 mm proximally under the PNF in the proximal nail groove to include all matrix tissue. The excised matrix is removed with fine scissors. Sutures or Steri-Strips are used to place the PNF into its normal position. Hemostasis is controlled by direct pressure and electrocoagulation.

Postoperatively, patients experience significant pain, morbidity, and prolonged healing.[14, 64] A possible complication of cold steel surgery with scalpel excision may be a higher rate of nail regrowth in the area of the lateral matrix horn; this regrowth is caused by inadequate removal of the matrix from this recessed area.[23, 44] Dorsally reflecting the PNF to fully expose the nail matrix helps to reduce the likelihood of this complication. After surgery, the extremity should be elevated to reduce subsequent pain and swelling. Local bupivacaine can be administered immediately after surgery to provide extended pain relief for at least 8-12 hours. Pain control is usually managed with acetaminophen with codeine.

Chemical matricectomy

Chemical cauterization of the nail matrix with the application of phenol is used to partially or permanently destroy the matrix. Phenol matricectomy is the most widely practiced matricectomy procedure.[9, 13, 64] Phenol denatures protein and retains antibacterial and anesthetic properties.[66] If the goal of surgery is to narrow the nail plate to correct the disparity of a nail too wide for its bed, a partial phenolization is performed.

After unilateral, partial bilateral, or total nail avulsion is performed under digital block, a number-1 curette is used for curettement of the hyponychium, the lateral nail groove, the lateral matrix horn, and the proximal matrix. Curettage appears to lower the rate of recurring nail spicules in the lateral nail horn area, resulting in higher cure rates and a better treatment outcome.[9] An exsanguinating tourniquet is used to maintain a bloodless surgical field for 2 reasons: (1) Blood is known to inactivate phenol.[9] (2) A dry surgical field helps to facilitate contact between the matrix and the chemocauterant.[23]

Before applying phenol, the surrounding soft tissues are covered with petroleum jelly to protect them against chemical damage and resulting chemonecrosis. A supersaturated solution of 88% phenol is used. A total of three 30-second applications of phenol are required in partial matricectomy and five 30-second applications are used in complete matricectomy.[13, 14] A sterile cotton-tipped applicator dipped in the concentrated phenol solution is directed laterally into the recessed area of the lateral matrix horn and dorsally to contact the matrix tissue on the

During the procedure, the cotton applicator is used to vigorously massage the matrix with a twisting motion.[9, 14] After phenol application, lavage of the treated area is performed by using 70% isopropyl alcohol to neutralize the concentrated phenol. Sodium chloride solution, boric acid, or 3-5% acetic acid may also be used to neutralize phenol.[23] It is recommended that the nail is lavaged with alcohol or alcohol plus chlorhexidine to effectively remove the phenol. If a single-step lavage is performed, then a combined-solution is preferred.[67] At this point, the tourniquet is removed. Bleeding is usually minimal and is controlled with aluminum chloride and direct pressure.

An antibiotic ointment, petroleum jelly gauze, and number-2 tube gauze are used to dress the wound. Elastoplast or Hypafix tape is placed to secure the dressing. The dressing is removed in 24 hours after a warm-water soak, and the wound is cleansed in diluted hydrogen peroxide solution. This procedure is the standard wound care used in all types of matricectomy procedures. The patient is instructed to perform dressing changes twice daily for 2-3 weeks. Soaking the wound in a warm, diluted Betadine solution may help to accelerate healing.

Phenol matricectomy has a success rate of 95% and higher,[9, 13, 64] and postoperative morbidity is minimal. However, the associated risks of performing this procedure include pain, frequent recurrence, periostitis, unpredictable persistent wound drainage, and extended healing times.[9, 64] The wound usually heals completely within 2-4 weeks by secondary intention.

Chemocauterization of the nail matrix is contraindicated in patients with vascular disease. A newer approach to chemocauterization of the nail matrix involves the use of 10% sodium hydroxide.[9] Chemocauterization of the nail matrix with sodium hydroxide is similar to the phenol alcohol method. One difference between the 2 procedures is the required use of a tourniquet for hemostasis in phenol matricectomy.

During the procedure, a cotton-tipped applicator is dipped in a solution of 10% sodium hydroxide and is carefully applied to all areas, including the proximal and lateral nail grooves, where matrix tissue is found. The endpoint of this procedure is the visible white blanching of the capillaries.[9] Once blanching is apparent, the sodium hydroxide is neutralized with 5% acetic acid. The success rate of this procedure reportedly parallels that of the phenol method. However, some nail surgeons prefer 10% sodium hydroxide because of decreased postoperative morbidity with lower recurrence rates, minimal drainage, and faster healing time. A surgeon experienced in sodium hydroxide matricectomy should perform the procedure to avoid excessive chemical-induced tissue destruction with resultant pain and prolonged healing. Chemonecrosis of the surrounding tissues is a potential problem with phenol matricectomy and sodium hydroxide matricectomy.

Ablative matricectomy

In the electrodesiccation and curettage method, the diseased portion of the nail plate is avulsed. A tourniquet is used only during the avulsion procedure. This procedure is followed by vigorous curettage of the exposed matrix and its lateral horn. Electrodesiccation of the area curetted is performed. To ensure complete destruction of all matrix tissue, electric current is applied twice to the treatment site for an estimated 5 seconds.[23] A cooling period of 10-20 seconds should occur between treatments. Excellent hemostasis is provided by means of electrocoagulation. A potential complication of this method is thermal destruction of the nail folds, the surrounding periungual tissues, and the underlying bony phalanx. This complication may be circumvented by using Teflon-coated probes to direct energy primarily to the matrix.[23]

Electrosurgical ablation of the nail matrix involves the use of an electrode that is directly applied to the matrix tissue, leading to its destruction. Matrix destruction is carried out independent of incisions and electrodesiccation. A dry surgical field must be maintained,[9] which is accomplished by applying a tourniquet before performing nail avulsion. The electrode has an insulated surface and an exposed surface.[9] The insulated surface protects the adjacent healthy tissues from electrical destruction. Bleeding is usually absent because of adequate electrocoagulation. This method is associated with a rapid healing time, a low recurrence rate, and little postoperative pain. However, scarring may be significantly greater than that seen with the laser technique.[14] Anesthesia must be adequate throughout the procedure.

Ablative matricectomy with carbon dioxide laser vaporization provides selective destruction of the matrix tissue. Carbon dioxide matricectomy is associated with minimal postoperative morbidity, protracted healing time, decreased edema and inflammation, and absence of extensive necrosis of the adjacent dermal tissue.[9] The carbon dioxide laser was first used in the treatment of onychogryphosis.[9]

Before laser treatment, 1% lidocaine is used to perform a digital block. The matrix may be curetted, and the PNF is reflected back with skin hooks to fully expose the matrix. Wet towels are placed around the surgical site to limit injury to the adjacent soft tissues. The laser beam is directed into the deep recessed areas of the lateral matrix horn and the ventral surface of the posterior nail fold,[64] completely obliterating all the matrix tissue and preventing recurrent nail growth. Hemostasis is well controlled.

After laser treatment, a bacitracin pressure dressing is placed over the digit. In 24 hours, the dressing is removed, the surgical site is cleansed, and bacitracin is reapplied. Dressing changes are performed 2-3 times daily over a period of several weeks. The surgical site heals by secondary intention, and healing is rapid with minimal patient discomfort. The advantage of carbon dioxide laser vaporization of the matrix is the use of a defocused laser beam that is limited in its depth of penetration.[9, 30, 68] Thus, laser energy is directed at only matrix tissues. Therefore, carbon dioxide laser vaporization of the matrix is as effective as the other methods in destroying the nail matrix.

Lasers in onychomycosis

The application of emerging laser technologies in the management of onychomycosis holds significant promise, relative to other treatment modalities in clearing clinical presentations of dermatophytic nail infection.

Bristow performed an electronic literature search on the effectiveness of lasers in the treatment of onychomycosis. He reviewed 12 studies consisting of two randomized controlled trials, four comparative design studies with no placebo or control, and six case series.[69]

He cited a relatively low level of evidence. Poor study methods and design were documented as negative contributing factors with limitations, including low power or smaller sample sizes, lack of control or placebo groups, and/or short follow-up intervals. Bristow also discussed the need for conformity in defining a clinical versus mycological cure of onychomycosis, as there remains confusion in the literature regarding this.[69]

In the published literature, there are only few well-designed double-blinded, randomized, controlled studies focused on this therapeutic area. Owing to the heterogeneity of studies performed on the clinical efficacy and safety of laser therapy in onychomycosis, a clear consensus has not been reached regarding standard treatment guidelines, optimal laser settings to achieve optimal results, and recommended treatment schedules.

The US Food and Drug Administration (FDA) has approved laser devices in the management of onychomycosis based on data showing transient clearance of dermatophytic nail infection rather than data reflecting a definitive fungal cure.[69]

Most lasers used to treat onychomycosis are in the near-infrared spectrum (wavelength of 780-3000 nm). The principles of selective photothermolysis are active, allowing short pulses of light energy into the target tissue along with adequate thermal relaxation permitting tissue cooling and circumventing collateral tissue damage. These lasers appear to work through direct heating of the target tissue, although their mechanism of action needs to be further elucidated.[69]

In the literature, lasers used to treat onychomycotic nails range from the 1064-nm Q-switched Nd:YAG, 1064-nm long-pulsed Nd:YAG, and 532-nm Q-switched Nd:YAG, to the Er:YAG 2964-nm and diode lasers, among others. Lasers are proposed to inhibit fungal nail growth, but again there exists incongruity in published studies demonstrating this proposed mechanism of action. Lasers may also assist topical antifungal drug delivery through nail-plate ablation or by created fenestrations in the nail plate.

Radical matricectomy

Radical matricectomy (the Syme procedure) is the radical en bloc excision of the entire nail complex. This procedure, which is less commonly performed today, is reserved for patients with symptomatic, recurrent onychocryptosis that is refractory to repeated treatments of total nail matricectomy. The plantar flap formed from amputation of the distal half of the terminal phalanx is sutured dorsally over the defect created from the excision of the nail bed and the nail matrix for primary wound closure.[9] Radical matricectomy has a success rate of almost 100%, with low postoperative morbidity, despite the poor cosmetic and functional outcome.[14]

Soft tissue resection for ingrown nails is performed in cases of lateral nail wall hypertrophy. This procedure spares the nail matrix and the nail plate, which most likely have a normal shape, and it removes the surrounding paronychial tissues. Soft tissue resection for ingrown nails can be performed in 3 ways: simple nail avulsion, peridigital resection, or elliptical wedge excision.

Simple (partial or complete) nail avulsion may be performed with a 1% lidocaine digital block, especially if significant pain and infection are present. Typically, removing a narrow strip of nail from the embedded side is adequate. Simple avulsion alone has low postoperative morbidity and an estimated cure rate of 30%,[5, 14] relieving pain and resolving infection in this presentation. In cases where granulation tissue has formed, electrodesiccation,[44] cauterization,[44] or excision is used to remove the excess tissue. If the hypertrophied granulation tissues epithelialize, scalpel excision or electrodesiccation with curettage is performed.[44] The patient is instructed to place cotton wool at the previously embedded site to keep the nail plate elevated. Repeated attempts at avulsion are associated with failed treatment outcomes and a greater risk of recurrence.

Peridigital resection may be used to treat the soft tissue hypertrophy. When this approach is used, 2 incisions are made: the first incision is a curved line, hugging the lateral surface of the digit, and the second incision is made parallel to the first and is extended to the underlying subcutaneous fat to remove a wedge-shaped sample of tissue. At closure, the nail folds in the nail groove are oriented away from the nail plate, limiting contact between the 2 structures.

Elliptical wedge excision of the lateral nail wall and the nail fold is a third option. At closure, Steri-Strips are placed to secure the nail plate to the newly created lateral nail wall.[14] Alternatively, interrupted 4-0 nylon sutures first passed through the skin and then the nail plate may be used to close the defect.

The success rate of the last 2 approaches is 50-70%.[14] In presentations where recurrence is extensive or where multiple sites are involved, cold steel excision followed by a single treatment of phenol on the wound is recommended.[14]

Paronychial surgery

The paronychial region is primarily defined by the PNF, the LNF, and the nail walls; the distal cuticle attached to the nail plate; and the ventrally situated eponychium.[1, 5, 11] These components of the nail unit function collectively to prevent infection and inflammation from reaching the proximal nail matrix. A physical or chemical insult most often precedes the introduction of inflammation or infection into the paronychial area. Examples of pathologic conditions that commonly involve the perionychium include acute and chronic paronychial infections, periungual and subungual verrucae, deep fungi, atypical mycobacteria, myxoid cysts, foreign body and pyogenic granulomas after trauma, and tumors (ie, periungual fibroma associated with tuberous sclerosis and acquired digital fibrokeratoma).[13]

Emergent antibiotic treatment is paramount in preventing permanent nail dystrophy. Before initiating treatment, culture and sensitivity studies for bacteria are performed. Staphylococcus aureus is the most common organism cultured in acute paronychial infection.[1, 5, 11] Other organisms less commonly identified in acute paronychia are Streptococci pyogenes and gram-negative enteric bacteria. Early empiric antimicrobial therapy with a broad-spectrum penicillinase-resistant antibiotic and a topical antimicrobial agent is recommended. Based on culture results, antibiotic treatment is later streamlined to cover the specific organism identified on culture. Wet compresses with Burrow solution, warm soaks, or alcoholic baths and elevation are also used to help control early infection.[5]

If the acute infection fails to respond to antibiotic treatment within 48 hours, surgical management is indicated. When present, pockets of collected pus can extend around the base of the nail under the PNF and inflame the nail matrix. The pus may dissect the nail away from its weaker underlying proximal attachment. A pressure necrosis can develop within 48 hours with resultant nail dystrophy that may be transient or permanent if surgery is delayed.

Before evacuating the pus, a proximal block is administered. A small incision is made parallel to the nail fold and directly over the collection of pus to drain the abscess. Baran and Bureau recommend incising the site of maximum pain rather than the site of maximum soft tissue induration. Formed septa in the abscess base are destroyed by using the tip of a curved hemostat.[13] If infection spreads under the distal nail bed (subungual extension), excision of the entire nail base along with distal avulsion is performed to expose the nail bed. Then, the nail bed is carefully debrided.

Postoperative care involves changing the dressing daily and moistening it with sodium chloride solution or an antiseptic solution. This process is performed daily and is continued until all purulent drainage has resolved.

In recalcitrant disease, a crescentic excision of the diseased nail fold along with the proximal nail plate is performed.[5, 13, 19] Healing occurs by secondary intention, restoring the normal anatomical barrier function of this area. Wound toilet includes the application of an antibiotic dressing. The patient should be instructed to avoid contact with water when possible and to protect the hands by wearing rubber gloves.

Another surgical approach is to excise the involved tissue and to create an eponychial pouch.[27] The Bunnell technique involves the avulsion of the proximal one third of the nail by cutting across with scissors followed by the placement of nonstick gauze under the PNF.[5] If the infection is confined to one side and has tracked beneath the nail plate, avulsion of the lateral nail adjacent to the infection is performed.

Chronic paronychia often involves fungi, most commonly Candida albicans. As a result, these patient are often placed on antifungals in addition to antibacterials and topical corticosteroids to address the concurrent bacterial infection, inflammation, and fibrosis. A new surgical technique is to remove the periungual fibrosis while preserving the epidermis. The new square-flap technique involves 4- to 5-mm oblique incisions along the PNF.[70] A subsequent incision is made parallel to the epidermis at the distal thickened PNF underneath the fibrotic tissue, while care is taken to not damage the underlying nail matrix.[70] The newly created square flap is then tilted backward and an incision on the LNF is performed to remove the fibrosis.[70] The surgical incision is closed with a simple interrupted suture.

Surgery of myxoid cysts

Myxoid cysts are usually asymptomatic. However, surgical removal of the cysts is indicated when they become too large and cause pressure on the underlying matrix, resulting in longitudinal nail deformities, such as splitting of and ridging on the nail plate. Other indications for surgery include pain, persistent drainage, and development of secondary infection. Conservative treatment may initially be attempted with intralesional corticosteroid injections or by freezing with cryotherapy.[13] Additional treatment strategies include the use of percutaneous sclerotherapy with sodium tetradecyl sulfate or polidocanol.[71, 72] When conservative measures prove unsuccessful, elective en bloc excision of the PNF is performed.[23] The goal during surgery is to perform a full-thickness excision of the PNF that includes symmetric small portions of the LNF.

Standard preparation of the digit is performed under sterile conditions. Effective anesthetic is administered, and a wide Penrose drain is applied for tourniquet action. A surgical pen is used to outline the area of planned excision. A Freer elevator is placed in the proximal nail groove to help define the proximal extent of the cyst and to direct movement of the scalpel. The Freer elevator should be positioned to move synchronously with and below the advancing scalpel to avoid cutting deeply into the matrix or cutting the proximal extensor tendon.[13] Hemostasis of the wound may be achieved by means of spot electrodesiccation.

Gelfoam or Instat pads are used to control capillary bleeding. A bulky, loose dressing is applied over the wound. The wound is cleansed twice daily with dilute hydrogen peroxide followed by the application of an antibiotic ointment and a replacement of the dressing. If the wound is allowed to heal by secondary intention, the new position of the PNF will be 3-5 mm more proximal to the original position.[13] This outcome is cosmetically appealing with a slender appearance to the digit. If the nail matrix is not permanently damaged, all deformity of the nail plate is expected to disappear in 4-6 months with new nail growth.

Surgery of warts

Treatment of warts is sometimes difficult, and recurrence is a contentious problem in certain patients. Carbon dioxide laser treatment, pulse dye laser ablation, and electrosurgery are reserved for cases of recalcitrant warts. Standard therapies that use cantharidin, cryosurgery, and keratolytics are commonly unsuccessful in eliminating the virus.[13] Despite this finding, cryosurgery by using liquid nitrogen to freeze the wart remains the most commonly practiced treatment approach.[5, 13, 73]

Three days before treatment, 10% salicylic acid is applied to the wart with occlusion to help accentuate freezing with liquid nitrogen.[17, 22, 23] Before salicylic acid treatment, subungual warts are first debrided. Liquid nitrogen is applied by a spraying action or by using a cotton-tipped applicator. The estimated freeze-thaw time is 30-45 seconds after which another treatment cycle can begin for a total of 2-3 cycles.[23] During the procedure, the patient may experience pain due to edema produced under the nail bed. If longer freezing times are desired, the patient is made comfortable by administering digital anesthetic. Freezing of the proximal nail bed should be limited to avoid permanent damage to the underlying nail matrix.

In certain patient populations, cryotherapy is associated with high cure rates and minimal complications. The postoperative complications of freezing include pain, blistering, and transient neuropathy; the open wound heals by secondary intention within 2-5 weeks.[23] Less common complications such as depigmentation, nail loss, Beau lines, transient neuropathy, and anesthesia may occur. Pain during the procedure is controlled by providing prophylactic analgesia with 600 mg of aspirin 2 hours before surgery. This regimen is continued 3 times daily for 3 days after surgery.

Electrosurgery

The application of low-voltage current by means of electrodesiccation and enucleation to dehydrate and detach the wart from the dermis has proven efficacy in the treatment of common warts of the nail unit recalcitrant to conservative measures. After administering a local anesthetic, the nail plate is debrided to allow visualization of the wart. Debridement is followed by a 2-step procedure that is designed to soften, destroy, demarcate, and separate the wart from its attachment to the dermis.[13, 23, 27]

In the first step (electrodesiccation), a needle is directly applied to the surface of small warts or intralesionally applied to larger, thicker warts under low-voltage current.[13] The current essentially cooks and vaporizes the contents of the wart. During surgery, bleeding may be profuse when neovascular dermal capillary loops are interrupted; bleeding is often controlled with electrocautery, Monsel solution, or Gelfoam pads. Moderate bleeding can be controlled with electrocautery or by digitally compressing the lateral digital arteries.

In the second step, the charred tissue is removed with a curette, carefully avoiding the dermis and the nail matrix to prevent scarring (enucleation). A smoke evacuator or a suction device is used to remove infectious airborne viral particles. Electrosurgery is associated with an excellent cure rate. However, scarring may be significant. Healing occurs by secondary intention in 3-4 weeks. Potential complications of this procedure include thermal injury to surrounding soft tissues and the adjacent bony phalanx.[23]

Bleomycin treatment

The intralesional injection of bleomycin is highly effective in controlling recalcitrant warts. Before treatment with bleomycin, local digital anesthesia may be performed to control the pain associated with the injection. A diluted concentration of bleomycin (1 µm/mL), mixed with sodium chloride solution, is used.[23] Rare but potential complications include nail dystrophy (if the matrix is contacted), persistent local necrosis, scarring, and local Raynaud phenomenon in patients with previous vascular insufficiency.[23] Bleomycin is contraindicated in women who are of reproductive age and who are capable of becoming pregnant.

Laser treatment

The carbon dioxide laser is beneficial in treating common warts of the nail unit. Patients with multiple infected digits and those who are immunocompromised are more likely to respond to laser treatment than surgical treatment.[74] The surgeon can have precise control of the depth of tissue destruction when using the carbon dioxide laser. Postoperatively, pain, edema, inflammation, and healing times are significantly reduced.

Before carbon dioxide laser vaporization of the wart, local anesthesia or a digital block is performed. Carbon dioxide laser vaporization of verrucae uses a defocused beam with minimal thermal scattering. For treatment of recalcitrant warts of the nail unit, a power setting of 2-10 W delivered with a 2-mm spot size is used.[23] The laser beam must be directed into the lateral sulcus to destroy deeply seated wart tissue.[74] Application of the laser beam is continued until all remnants of infected wart tissue are removed. Tissue damage is minimal if exposure duration is appropriately managed.

Superpulsing delivers high-energy pulses with durations of 0.1-100 milliseconds and repetitions of 100 pulses per second.[74] This technique appears to be effective in decreasing the potential for thermal injury to soft tissues and the underlying bone. Overall, thermal damage with laser treatment is much less than that of electrosurgery.[5] Possible thermal injury to the nail matrix may occur because periungual warts usually involve the PNF overlying the proximal matrix. Hypertrophic scarring and permanent onycholysis of the nail plate may be seen in excessive thermal damage to the nail bed.[68]

When managing subungual warts, the nail plate may initially be debrided or directly vaporized without debridement. To fully appreciate the extent of subungual involvement, a partial or complete nail avulsion is usually appropriate. In certain cases, nail avulsion can be avoided. The charred tissue is curetted or excised with scissors. Another approach is the use of electrosurgery to remove most of the wart tissue followed by laser treatment to vaporize the remaining wart tissue. Adjuvant therapies with an associated low morbidity can be used after laser treatment to treat small recurrences.

The Nd:YAG laser at a low-power setting of up to 20 W and a spot size of 2 mm has been used in the treatment of periungual and subungual warts as well as plantar warts. The lesion is irradiated until a whitish discoloration appears. The advantages of this laser treatment include minimal bleeding and the absence of smoke plume, thus preventing exposure to infectious viral particles. The benefits of the carbon dioxide laser over the Nd:YAG laser are an accurate depth of tissue ablation, a reduced residual coagulation zone, and a decreased potential for scarring with less postoperative pain and faster healing.[5, 75]

The flashlamp pulsed dye laser has recently been reported as an alternative laser treatment for resistant verrucae, especially of the plantar type. The primary method of destruction is through the application of laser energy to ablate and coagulate the dilated capillaries supplying the wart.[68] The benefits of using this type of laser therapy include eliminating the requirement for an anesthetic and sparing collagen tissue from destruction. Patients also remain ambulatory and functional in the immediate postsurgical period. However, experience and outcome with this approach have been mixed in reviews of the medical literature.

Surgery to repair nail trauma

An accurate physical examination, including radiographic studies to establish the presence of bony fractures and to assist in wound exploration, must be expeditiously performed. The physical examination should focus on determining if paresthesia is present distally and palpating for pulses to establish the sensory and vascular status of the distal finger; evaluating joint stability by checking active and passive range of motion; and observing the involved area for swelling, discoloration, deformity, and shortening. Culturing and staining with Gram stain should be performed on wounds suspected of being contaminated.

The standard preparation for hand surgery includes thorough cleansing of the involved extremity to above the elbow to prepare graft harvest sites. The injured digit is prepared in a sterile field and irrigated with sodium chloride solution. Before the extremity is exsanguinated, broad-spectrum antibiotics are administered to allow adequate tissue exposure during surgery when the wound appears to be infected.[27] The sterilized tray of instruments should contain the instruments that are typically used in performing surgery of the nail unit.

Adequate hemostasis is critical in maintaining a bloodless field, thus minimizing the potential for injury to deeper structures. Hemostasis of the digit may be achieved by placing a sterile surgical glove on the hand and cutting a hole in the tip of the finger. The finger of the glove is rolled toward the base of the digit to function as a tourniquet and to increase the effectiveness of the digital block. Alternatively, a Penrose drain tourniquet may be used to achieve hemostasis. Vasoconstriction is avoided to prevent ischemic necrosis of the digit. A proximal forearm tourniquet is used when surgery is performed on the palm or dorsum of the hand.[76] This tourniquet is removed after 25-30 minutes because a longer application results in significant pain. During surgery, electrocauterization is used to control bleeding.

Surgery of subungual hematomas

Management of subungual hematomas largely depends on their size, location, and presentation. Hematomas that occupy 25% or more of the nail bed are evacuated by creating a small puncture hole through the nail plate by using a number-18 needle, a paper clip, a drill, and an acute-tipped scalpel heated over an alcohol lamp or a handheld electrocautery unit.[27, 77] A slow, constant pressure is applied to the center of the nail plate to puncture the plate and to allow drainage of the hematoma. Incomplete evacuation may require a second penetration of the plate. After complete drainage, adherence of the nail plate to the nail bed is ascertained by bogging down the plate with a tight bandage. Trephination of the nail plate provides almost immediate pain relief, and the risk of complications, such as infection and nail dystrophy, are absent with this procedure.

Surgical evacuation of the hematoma may help to salvage the nail. If the hematoma is not removed, nail attachments are loosened, and the nail falls off to be replaced by a new healthy nail several weeks after the trauma. Large or total hematomas may indicate a fractured distal phalanx with significant lacerations of the matrix and the nail bed.[5, 23] Prolonged pressure on the matrix leads to permanent nail dystrophy.

Radiography is indicated to exclude fracture because the size of the hematoma and the presence of an underlying fracture are poorly correlated.[23] When evacuating a large hematoma, the nail plate is first avulsed. The nail bed and matrix are carefully explored and examined, and the hematoma is removed. Any laceration of the nail bed is sutured by using 6-0 Dexon sutures or polydioxanone (PDS) 6-0 sutures. The avulsed plate should be cleaned, trimmed, and reattached to the nail bed and the LNFs by using horizontally placed mattress sutures. Stitches are removed in 10 days, when the nail is firmly adherent to the nail bed. Anesthesia is usually not required, but, when indicated, a digital block may be performed.

Repair of simple lacerations

Superficial lacerations that are limited to the nail plate and involve less than 3 mm of the nail bed usually heal independent of surgical repair as the injured nail grows out.[5, 23] Larger lacerations of the nail bed (due to displacement of the nail plate) with phalangeal fracture must be surgically repaired.

If the nail matrix is involved, a careful inspection of the matrix followed by surgical repair is required to avoid nail deformity. In this case, the distal nail plate must be avulsed far enough proximally to allow visualization and placement of sutures in the lacerated matrix. The proximal most aspect of the nail plate is left in place to protect the matrix. Any nail bed tissue that is firmly attached to the avulsed plate should be left intact.[23] The injured nail tissue is irrigated and conservatively debrided to avoid removing viable nail tissue. The lacerated nail bed and the matrix are repaired with interrupted 5-0 or 6-0 absorbable sutures.

The avulsed nail is cleaned, trimmed, and reattached to the nail bed. The repaired nail is dressed with sterile petroleum jelly gauze or Xerofoam, followed by a soft, thick dressing that is loosely applied. If the nail plate is damaged beyond recognition and cannot be salvaged, nonadherent gauze is placed on the exposed nail bed. The gauze is replaced at each dressing change. Lacerations of the hyponychium and the LNF are repaired by using 5-0 or 6-0 nylon sutures.

Repair of complex or stellate lacerations

During repair, a complete nail avulsion is performed to fully expose the nail matrix. A Freer elevator is used for separation, and a hemostat is used for avulsion. After avulsion, the wound is carefully debrided. Then, the wound edges are accurately reapposed. To avoid future nail deformity, the nail root and the nail bed are carefully aligned and replaced on the finger by using 5-0 or 6-0 absorbable mattress sutures. Improper management of a complex lacerating injury may result in secondary nail changes, such as nail dystrophy, onycholysis, pterygium, or a malaligned nail plate due to a malpositioned matrix.[1, 5, 27]

Repair of avulsive lacerations

Partial avulsive lacerations of the nail bed with loss of nail plate adherence are surgically treated with split-thickness nail matrix grafts obtained from the same nail bed or from the great toe.[27] Other choices for repairing nail bed avulsions include full-thickness nail bed grafts, split-thickness nail bed grafts, split-thickness skin grafts, or reverse dermal grafts.

Avulsive lacerations of the PNF are repaired with a local rotational flap from the dorsal digital skin combined with a small, split-thickness skin graft.[5, 27]

In cases of extensive avulsive lacerations, a cross pedicle flap or a cross arm flap is used. Packing the nail fold space with nonadherent gauze prevents formation of adhesions between the PNF and the nail bed. A thin, split-thickness skin graft may also be used in place of gauze packing. An overlying stent dressing may be placed to prevent a hematoma from developing under the graft. A nail plate that is relatively large can be used as a stent by replacing the plate beneath the PNF[27] after the plate has been cleaned in an antimicrobial solution. The lacerated PNF and groove is repaired with 7-0 chromic gut sutures. The dorsal surface of the PNF is repaired with nylon sutures. The cleaned nail plate or a substitute is replaced and sutured with nonabsorbable mattress sutures.

A full-thickness nail bed graft is positioned over the ventral bony phalanx if the nail pulp is lost and the bone is exposed. A split-thickness skin graft or free nail graft is applied when the avulsed matrix is lost.[5, 27] Healing by secondary intention produces an acceptable outcome. If healing of complex avulsive lacerations is inadequate within 6 weeks, a thin, split-thickness skin graft is used. After nail unit avulsive injuries are repaired, the dressing must allow the nail to heal without further trauma or injury, it must be nonadherent to prevent adhesions from forming between the nail matrix and the PNF, and it must be able to maintain the shape of the nail bed.

Repair of fractures

Stable fractures that are not anatomically displaced do not require manipulation by reduction; however, they should be protected from potential trauma. If a fracture is unstable, it must be immobilized and reduced through closed reduction with external splinting of the injured finger to the adjacent digit.

Tuft and shaft fractures of the distal phalanx are usually caused by crush injuries. They commonly present with comminution and mild displacement of the distal phalanx.[24] Treatment is primarily targeted at the injured soft tissues. Tuft fractures frequently present with distal subungual hematoma and multiple bone fragments, with preservation of the nail pulp.[24] This fracture type requires more aggressive treatment to retard the development of pseudoarthrosis and to reduce instability from residual bone fragments left behind. The wound should be well irrigated to completely remove all bone fragments. After inspection, debridement, and irrigation, the wound is sutured and closed.

Shaft fractures are divided into single-transverse, multiple, and open fractures.[23] Management of single-transverse shaft fractures involves fracture reduction with proper alignment to restore the shape and outline of the finger. After avulsion, the nail bed is inspected, and the lacerated edges are reapproximated and sutured to reverse the impinging force. Fluoroscopically guided percutaneous placement of Kirschner wires help to secure the closed reduction.[23] Multiple shaft fractures are managed by fixation and repair of the soft tissue injury[23] after the wound is irrigated. The removal of bony fragments shortens the length of the finger while permitting the fracture ends to reconnect.[5] Plastic surgery may be attempted to restore the length of the finger.

Open fractures that are extensive and involve the DIP joint are treated by amputation or ankylosis (joint fusion) at a 180° angle.[5] After repair of terminal phalanx fractures, the patient is instructed to elevate the extremity for at least 48 hours to help relieve pain and swelling. After 1 month, the patient should return for the removal of external splints and internal fixation wires. Physical therapy may be helpful in accelerating healing. When appropriate, tetanus prophylaxis should be considered; compound fractures and open wounds sustained 6-8 hours before presentation should be treated with oral antibiotics for 1 week.

Lacerations of the nail bed and the nail matrix are repaired as previously outlined. Incomplete debridement of the soft tissue and the nail matrix from between bone fragments results in nonunion and poor healing of the fracture.[27] In the event that pseudoarthrosis develops, it is managed by positioning bone grafts on the ventral surface of the tuft and by using Kirschner wires to transfix the fragments and to restore stability. Kirschner wires are generally useful in transfixing bone fragments to maintain length and alignment when the fracture is not extensively comminuted.[27]

Treatment of splinter hemorrhage

In a young, healthy patient, splinter hemorrhages are explained by a history of minor trauma and require no further investigation. Treatment of splinter hemorrhages should be directed at resolving the underlying cause.

Surgery of nail unit tumors

Surgery of pyogenic granulomas

Surgical management of the granuloma is by means of an excision. An electrocauterizing unit or a scalpel is used to perform the excision at the base of the lesion. Biopsy is used to confirm the diagnosis.

Surgery of fibroadenomas

Treatment is determined by the size and the location of the lesion. Treatment involves local excision and the use of a skin graft or reconstruction of the nail bed.

Surgery of glomus tumors

Smaller glomus tumors are excised by creating a 6-mm punched out hole in the nail plate. An incision is made through this hole, enucleating the tumor from its fibrous covering and incising the nail bed tissue. The punched out nail disc is replaced to function as a physiologic dressing. Surgical treatment of larger glomus tumors begins with proximal nail avulsion. The matrix and the nail bed are incised and elevated from the periosteum. Then, the tumor is excised. A nonadhesive gauze pad is placed on the wound to prevent the formation of adhesions between the nail bed and the skin fold. Standard wound care is necessary after surgery.

Surgery of subungual exostoses

Radiographic changes (trabeculated bony growth with an expanded distal area layered by radiolucent cartilage) confirmed on radiographs are diagnostic.[5] Surgical excision of the bony growth is performed under aseptic conditions. A partial nail avulsion is carried out and followed by a longitudinal incision in the nail bed. The tumor is carefully separated from the underlying nail bed, and it is removed with a fine chisel. Alternatively, the nail plate may remain intact, and the bony growth is removed through an L -shaped incision.

Surgery of basal cell carcinoma, squamous cell carcinoma, and melanoma

Surgical management of basal cell carcinoma, SCC, and melanoma in established cases involves excision of the tumor with clear margins if bone metastasis is absent; this is usually accomplished by Mohs micrographic surgery. The surgical site is covered with a skin graft, and the patient is closely monitored for recurrence. If bone metastasis has occurred, the extremity is amputated at the DIP joint or more proximally.[27] Subungual melanoma can be managed by metacarpal or metatarsal ray amputation.[27] Dissection of the regional nodes may be required.

Mohs micrographic surgery has been recommended in the treatment of well-differentiated, potentially aggressive tumors of the nail unit.[5, 78] The Mohs technique of horizontal sectioning allows examination of 100% of peripheral and deep tissue margins of the specimen, resulting in the smallest possible defect and the highest possible cure rates.

The Mohs technique has been found to be especially effective in treating Bowen disease (SCC in situ) and SCC involving the periungual and subungual components of the nail unit in the absence of osseous involvement. It has also been indicated for the treatment of recurrent basal cell carcinoma.[78]

In presentations of histologically confirmed SCC of the nail unit, destruction of the underlying bone by invasive disease must be excluded on radiographic examination of the affected digit. If bone involvement is established, the patient is scheduled to undergo amputation of the digit at or proximal to the DIP joint. With either a fixed-tissue technique or a fresh-tissue technique, the surgeon can extensively examine the undersurface and peripheral edges of the excised tissue.

The fixed-tissue technique requires in situ fixation of the tissue specimen with zinc chloride paste, a chemical fixative that maintains a bloodless surgical field. The addition of the fixative to neoplastic tissue prevents the tumor from spreading while the lesion is being excised.[78] The fixed-tissue technique is less favored than the fresh-tissue technique because of significant patient discomfort and the excessive time requirement. It takes approximately 12-24 hours to satisfactorily fix the specimen with this method. Moreover, a pronounced local inflammatory reaction to the chemical fixative that may interfere with the evaluation of the tissue specimen at histologic examination may develop in some patients.[78] For pain management, both an oral pain medication and a local anesthetic are usually administered to the patient.

An advantage of using the fixed-tissue technique is its usefulness in handling aggressive SCCs in highly vascularized regions such as the nail bed, an area susceptible to bleeding and from which thin slices of nail tissue are removed. The surgical defect created by the fixed-tissue technique heals by secondary intention. With the fresh-tissue technique, patient discomfort is significantly less and the procedure time is quicker, making this the preferred method. No chemical fixative is needed with the fresh-tissue technique. Here, the surgical defect is repaired with a skin flap or a skin graft, or it is allowed to heal by secondary intention.

The benefits of applying Mohs micrographic surgery in treating nail unit tumors include the following: (1) The Mohs technique is a nail-sparing procedure that provides high cure rate.[78] The treatment outcome is excellent in cases of localized disease. (2) Mohs micrographic surgery is ideal for obtaining tumor-free margins, while maximally preserving the integrity of the surrounding healthy tissues.[5, 78] (3) The Mohs micrographic technique is an alternative to amputation by providing the option of preserving the nail unit and maintaining digital function in cases where the tumor has not yet invaded the underlying deep structures. (4) The Mohs surgical technique is both diagnostic and therapeutic. In general, when nail unit tumors are treated, the performance of Mohs micrographic surgery versus cold steel surgery with wide tumor excision have similar documented cure rates.

Preoperative Details

The preoperative evaluation of the patient scheduled to undergo nail surgery should include a medical history and a physical examination. A targeted dermatologic examination with inspection of the hair, skin, and nails is advisable. The history of present illness and the clinical signs and symptoms leading to the current presentation should be documented. Previous dermatologic disease and treatments, including past surgeries, should be obtained. A list of current medications and any allergy history are essential. A directed inquiry into any history of a bleeding disorder is pertinent to uncovering a dysfunction of hemostasis that could result in excessive blood loss during surgery. Preliminary laboratory tests to determine clotting function and complete blood count are performed when indicated.

Any patient presenting with an acute infection or inflammation of the nail and surrounding soft tissues, such as acute paronychia, should be considered for future nail surgery. In the presence of active infection, all elective nail procedures are better deferred until the infection is appropriately managed with antibiotic coverage and soaks.

In clinical presentations, such as ingrown toenails with painful penetration of the LNF skin by the nail plate, postponement of surgery may not be an option. The patient should be instructed to discontinue all anticoagulants, including aspirinlike products, 1 week before surgery. The nail surgeon should schedule a meeting with the patient to discuss the potential risks and benefits of the surgical procedure to be performed, the expected healing time, the potential postsurgical complications, and the possibility of long-term structural or functional deformity of the nail.

Anesthesia

Appropriate anesthesia of the nail unit is paramount before starting nail surgery. When effective anesthesia and good technique are used, pain is well controlled and patient anxiety is decreased, greatly improving the likelihood of a successful surgical outcome. The following four factors can be used as guidelines in selecting the type of anesthesia for nail surgery:

  • The time of onset of the selected anesthetic[5]

  • The duration of action of the anesthetic, which is critical if the surgeon is to deliver safe and adequate pain control intraoperatively and postoperatively[5]

  • The potency of the anesthetic agent[5]

  • The surgeon's familiarity with the potential adverse effects of the agent and the steps used to reverse these effects

In general, the risk of experiencing untoward adverse effects (local and systemic toxicity) during nail surgery are minimal if the surgeon is familiar with the anesthetic used and is experienced in managing potential complications that may occur. Before surgery, the surgeon should meet with the patient to discuss the type and method of anesthesia that will be used during the procedure. Assuring the patient that the chosen method of anesthesia is safe and effective in delivering adequate pain control with a low risk of adverse effects is important.

Several methods can be used by the nail surgeon to induce anesthesia with maximal effectiveness. A choice of local or regional block anesthesia is available. In some cases, local anesthesia alone is sufficient. There are three main anesthetics that are used in digital anesthesia: lidocaine, bupivacaine, and ropivacaine.

Lidocaine hydrochloride 1% or 2% is the most commonly used local anesthetic agent in nail surgery.[5, 31] Lidocaine is highly effective and has a low incidence of allergic reactions. Lidocaine also has vasodilating properties. Thus, injecting a large volume of lidocaine (>3 mL) may result in vascular compromise with vasospasm and tamponade and should be avoided.[13, 58] Lidocaine has an almost immediate onset (as short as 1 minute) and an anesthetic effect lasting 1-2 hours depending on local factors, such as the vascularity of the injected site, and the presence of vascular compromise, such as vasospasm or vasoconstriction.

Bupivacaine (Marcaine) 0.25% is especially effective in nail surgery performed for onychocryptosis or ingrown toenails and provides extended pain relief for as long as 24 hours. An alternative to bupivacaine is the combination of 0.5% bupivacaine and 1% prilocaine administered in a 1:1 ratio.[13, 23, 43]

Ropivacaine represents the current ideal given the short onset of action (1-15 min), prolonged duration, less cardiotoxicity than bupivacaine, and potential vasoconstrictive effects.[35] A downside to longer-acting agents is the risk of masking pain associated with postoperative complications such as ischemia, infection, and compartment syndrome.[79]

Mepivacaine hydrochloride 1% or 2% may be used in patients with a known sensitivity to lidocaine. Mepivacaine is longer acting and achieves better hemostasis. ref2} Carbocaine, bupivacaine, and etidocaine are other longer-acting agents that may be used when surgery is expected to be prolonged.

Epinephrine has vasoconstricting properties and may be used to extend the duration of action of the local anesthetic by slowing capillary blood flow at the injected site, thus decreasing the clearance of the anesthetic from the site and reducing blood loss. When epinephrine is used with lidocaine, it should be diluted to a factor of 1:100,000. A Cochrane review and meta-analysis supports the admixture of lidocaine with epinephrine and buffering with 1-1.8 mL of 8.4% sodium bicarbonate to 10 mL of lidocaine premixed with epinephrine to produce a mixture with near physiologic pH.[80] The combination of using a buffering agent and warming the anesthetic provides a less painful injection without loss of efficacy of duration of action.[81]

The two broad categories of digital anesthesia administration are (1) infiltrative and (2) nerve blocks. Infiltrative anesthesia is nearly instantaneous and blocks initial transmission of nociception, whereas nerve blocks require longer time of onset and block depolarization.[35]

For infiltrative anesthesia, a distal digital nerve block or wing block is best used for surgery involving the nail matrix or nail folds.[13] Anesthetizing the dorsal branch of the digital nerve is associated with less pain, and is therefore the preferred approach. A 30-gauge needle is slowly inserted at 3 mm proximal to the junction of the PNF and the LNF, blanching and distending both folds,[13] and the needle is continued distally and inferiorly to include the lateral digital nerves and its branches. This procedure is repeated on the opposite side of the finger. Slow insertion of the needle reduces the burning sensation that usually occurs. The terminal transverse and descending branches of the digital nerve are anesthetized by initially directing the needle transversely and then distally.[13]

For nerve blocks, these can be divided into traditional digital block or traditional transthecal block.

A traditional digital nerve block or base block anesthetizes both proper dorsal and proper palmar digital nerves near the base of the digit and directs it toward the proximal phalanx.[13] There are two approaches to the level of needle insertion. One option is to inject in the supraperiosteal plane, which is most efficient albeit risks injury to the nerve itself or adjacent vascular structures.[82] Alternatively, the needle is inserted at the midpoint between the dorsal and ventral surfaces near the base of the digit to create a dermal wheal and is continued toward the proximal phalanx. This procedure is repeated on the other side of the digit, which requires a second injection. If both blocks are performed, excellent anesthesia is achieved.[13, 40, 43]

The traditional transthecal block has the advantage of a single injection but has the potential for more postoperative pain. The palmar single-injection technique relies on the dominant volar digital nerves of the digits. The needle extends through the flexor tendon and tendon sheath to the ostium, followed by slow withdrawal while applying pressure to the plunger. Once the tendon sheath is reached, there is a loss of resistance and approximately 3 mm of anesthesia is injected.[35] An alternative subcutaneous technique involves more superficial penetration into the tendon sheath at the palmar-digital creases in order to minimize the risk of tendon injury or infection.[35]

Wrist blocks of the median or ulnar nerve, axillary blocks, and intravenous regional blocks are other useful approaches in administering anesthesia.[4, 5, 27] Avoiding injection of a large volume of anesthetic (>3 mL) is important because swelling may cause vascular compromise.

Adequate hemostasis is maintained by using the thumb and the forefinger to digitally compress the lateral digital arteries. A small, wide Penrose drain secured by a hemostat is usually placed at the base of the finger to control bleeding. Optimal hemostasis is achieved when the tourniquet is applied during the most critical part of the surgery and is kept on for a maximum time of 15 minutes. Tourniquets made of rubber bands or those that are constricting, small, or twisted are problematic and should not be used in nail surgery.[13]

Vasovagal responses are not uncommon during the administration of anesthetic. Therefore, the patient should be placed in a supine position before starting the procedure. To avoid abrupt movements while inserting the needle, inform the patient that they will feel a needle stick. During surgery, the patient should be frequently assessed for the development of new pain and changes in the pattern of pain.

Instrumentation

Many of the instruments used in surgical exploration of the nail unit are also used for atraumatic cutaneous surgery, with a few exceptions. The sterilized tray of instruments used in nail surgery should contain certain standard instrumentation, including a Freer septum elevator, a dental spatula, a mosquito hemostat (blunt ended), a nail splitter, a nail clipper or nail cutter, a double-action blunt-nose bone rongeur, double-action bone-cutting forceps, splinter forceps, nail extraction forceps, ingrown nail scissors, curved iris scissors, flexible retractors or rake retractors, single- and double-pronged skin hooks, a Bard-Parker blade and knife, 4-0 nylon sutures, a needle holder, and sterile gauze. The surgeon might choose to include additional instruments, such as a punch biopsy and an electrocautery device. A brief description of some of the instruments used in nail surgery follows.

The mosquito hemostat equipped with a clamp mechanism may be used to disrupt and free the nail plate from the nail bed. The grooved surface of the hemostat is positioned under the ventral nail plate surface. Once the plate has been dissected away from the nail bed, the hemostat is clamped down,[83] and, with moderate traction, the nail plate is lifted and removed. The hemostat method secures the nail plate and allows easier handling and manipulation. However, a drawback is the requirement of repeated forward and backward strokes to free the nail plate from the nail bed, which may inflict undue trauma on the nail bed. Repeated strokes are required with the blade of the hemostat, which is narrow and has a rounded undersurface. Some nail surgeons are not advocates of using the hemostat in nail surgery because of the traumatic manner in which it is applied.

The dental spatula with its thinner body and wider surface[83] area can be used to dissect the nail bed from the nail plate. Most surgeons prefer the dental spatula because it provides a clean atraumatic separation of the nail plate from the nail bed, with fewer required movements.

The Freer septum elevator functions in a manner similar to that of the dental spatula, and it can be used interchangeably with the spatula for total nail avulsions. The concave and convex surfaces of the septum elevator closely match the contours of the nail plate and the nail bed.[13] The Freer elevator also assists in defining the proximal nail groove and prevents the surgeon from cutting too deep during nail surgery. The Freer elevator may be used to retract the PNF.

The nail splitter consists of a wedge-shaped lower blade and a scissorslike upper blade. It appears to be useful in partial avulsions, especially in presentations of onychauxis with hard, thickened nails. Specifically, the nail splitter is effective in removing a longitudinal strip of the nail plate when treating ingrown nails. During nail surgery, the lower blade is used to dissect the nail plate from the nail bed, while the upper blade is used to cut through the nail plate.[13]

The nail clipper is rigid and is used strictly for the purpose of nail clipping, especially when the nail is thickened.

Double-action bone-cutting forceps are indispensable when used for trimming and paring of the nail plate.[13]

The Sears nail avulsion clamp combines the properties of the hemostat clamp and the Freer elevator or nail spatula. One hemostat blade has been modified and replaced by a nail elevator. The other blade is unchanged. This instrument is invaluable in nail avulsions performed on larger or thicker nails. The Iowa-Freer avulsion clamp is essentially a hemostat clamp that has one blade replaced with a narrower Freer elevator.[83] The matching blade is unchanged, except it is curved to complement the curve on the Freer elevator. The Iowa-Freer clamp is most useful for avulsions of smaller toenails and fingernails and for partial avulsions.[83]

Standard and Beaver knife handles are useful for nail biopsy. Nail pulling forceps are helpful in grasping and securing the nail plate after separation and before avulsion. Ingrown nail scissors are practical for removing nail spicules piercing the lateral wall epithelium in patients with ingrown nails.

Battery-powered cordless thermoregulatory units are used to cut through select areas of the nail plate in suspected localized disease.[26, 50, 51] These units cause minimal, if any, trauma to the specimen, the nail complex, and surrounding tissues. Thermoregulatory units are especially useful in performing biopsy on the nail bed. The advantages of cauterization units in nail surgery include relatively painless procedures, a bloodless surgical field, and a short procedure time. The units are supplied with interchangeable fine- and loop-tip filaments, and they operate at temperatures of 800-2300°F.[50, 51] In nail avulsions, the tip filament is allowed to become hot to adequately remove the nail plate.

Low-temperature noncutting units are not recommended because these units produce heat that is transferable to local tissues, resulting in thermal injury and delayed wound healing. However, the use of hot cautery units is also not advised because they usually cut through the nails quickly, causing significant tissue damage.[50, 51] Smoke plume from the vaporization of keratin during the cauterization process is best removed with a wall or portable suction device. Removal of the smoke plume is necessary in minimizing exposure to infectious particles that may be present.

Skin hooks are used to retract the PNF to allow exposure of the matrix, such as in matricectomy. A wide Penrose drain secured with a hemostat clamp is used as a tourniquet to maintain a bloodless field in short nail procedures. The tourniquet should be applied at the most crucial point in the surgery and removed within 15 minutes of application to prevent ischemia and vascular compromise. When indicated, an exsanguinating tourniquet created from the cuff of a surgical glove is used to wrap the involved digit into overlapping circumferential bands, beginning distally and moving toward the base of the finger, thus ensuring a dry, bloodless field.

Postoperative Details

After biopsy of the nail unit has been completed, the tourniquet is immediately released. The nail should be cleansed of all debris and treated with an antiseptic solution. An antibiotic ointment or nonadherent antibiotic tulle gauze is applied. Next, a bulky tubular dressing is placed to cushion against trauma and pain.

The ideal dressing should be nonocclusive and nonadherent, sufficiently absorbent to collect serosanguineous drainage, and sufficiently elastic to accommodate moderate postsurgical swelling.[13] Optimally, a nonstick Telfa dressing or release is used to cover the wound. Paper tape, longitudinally placed, is used to hold the dressing in place without creating a constricting band effect. The tape should not be completely wrapped around the digit. Wrapping the finger tightly can cause neurovascular compromise, venous congestion, edema, and pain.[4, 41] Several overlapping layers of X-span tubing or a Surgitube dressing is used to further support the bulky dressing that is again secured with paper tape.

Postoperatively, the extremity should be kept elevated for at least 48 hours to help decrease swelling and pain. Complaints of pulsating pain at the surgical site on the second postsurgical day may be suggestive of a wound infection.[1, 4] If this occurs, the dressing is removed, the sutures are opened, and the wound is drained. Unless the infection is extensive, an antibiotic is not required. The presence of sharp pain may indicate tight suturing of the skin.[1] Persistent pain requires opening and removing the sutures. The first dressing change is scheduled after 24 hours and then once or twice daily until the wound is completely healed and no exudation is present.

Daily wound care is important in preventing infection and involves cleansing the wound area with soap and water or hydrogen peroxide, applying an antibiotic ointment on the wound, and placing a new dressing. To minimize discomfort from adhesions formed from dry blood, the finger may be soaked in 1-3% hydrogen peroxide for 15 minutes before the first dressing is changed. In the later stages of healing, the wound is dressed with ointment and a Telfa pad, and it is secured with tape. Pain is controlled with oral analgesics, such as acetaminophen and codeine, or nonsteroidal anti-inflammatory drugs. Orthopedic Reese or Zimmer boots are used to help immobilize and protect the nail after toenail surgery.[13]

After fingernail surgery, an arm sling may be used to keep the upper limb elevated. After surgery is completed, if hemostasis is not adequate, Gelfoam (oxidized cellulose) or collagen matrix sponges are placed beneath the nonstick Telfa pad. Monsel solution is not recommended at this point because its use may lead to tattooing of the healed wound. Before being discharged, the patient should be warned that throbbing, pain, swelling, bleeding, exudation, and easy traumatization may occur.

Follow-up

For patient education resources, see the Skin Conditions and Beauty Center and Infections Center. Also, see the patient education articles Subungual Hematoma (Bleeding Under Nail), Nail Psoriasis, and Onychomycosis.