Nail Surgery


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.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,

Before Skin Surgery After Skin Surgery



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 Performing successful nail surgery requires a comprehensive understanding of nail anatomy and physiology.6 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.

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.1,7,8 The infectious process initiates in the lateral perionychium and is followed by the development of erythema, intense inflammation, swelling, pain, and local tenderness. 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.9 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 warm moistened environment is ideal for bacterial proliferation. Secondary Candida and bacterial infections (eg, Pseudomonas aeruginosa, Staphylococcus aureus) are implicated in acute exacerbations.10 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.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).2,7,11

In onychocryptosis, the primary direction of nail growth is lateral instead of the normal, forward orientation of nail growth in the longitudinal plane. 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.10 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. Myxoid cysts

Myxoid cysts are dome-shaped, translucent, solitary nodules occurring on the dorsal aspect of the finger.10,12,13 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.12 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.10,14 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.10,15 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). 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.10

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.1,7 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.7,9,16 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.9 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.

o 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.9 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.

o 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.17 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.17 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.18 Fracture of the distal phalanx occurs in approximately one half of nail bed injuries. The type of fracture (open vs closed),17 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.1,7 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.1,7,19 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.7 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.19 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.20 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.7,9 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.7,9,13 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.7,21

* 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.7,9 Subungual exostosis is not a true tumor.7 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.

* Basal cell carcinoma, squamous cell carcinoma, and melanoma: Although cutaneous malignancy is the most common form of cancer, malignancy involving the nail unit is a relatively uncommon phenomenon. When the nail unit is affected by cancer, it is usually a SCC that rarely metastasizes. Although curable in most cases, SCC of the nail complex is potentially fatal if not aggressively treated. Subungual melanoma is another rare malignancy of the nail unit that is commonly mistaken for other benign and malignant tumors, thus prolonging accurate diagnosis and early treatment.
(Reference to: http://emedicine.medscape.com/article/1126725-overview)