Eric Stuffmann and Jeffrey Yao
DEFINITION
An acute paronychia is an infection of the soft tissue fold around the fingernail.
It is the most common soft tissue infection of the hand.
The most common infecting organism is Staphylococcus aureus, although these infections are commonly mixed infections.
A chronic paronychia is characterized by repeated infection and inflammation of the eponychium.
The eponychium becomes thickened and rounded.
This problem often occurs in the setting of repeated and prolonged exposure to water.
The most commonly isolated organisms are Candida albicans, gram-positive cocci, gram-negative rods, and Mycobacterium spp.
Herpetic whitlow is caused by an outbreak of herpes simplex virus in the skin of the finger and can be confused with acute paronychia or felon.
Herpetic whitlow is common in children and medical personnel who come into contact with oral secretions.
A felon is a tense abscess of the distal pulp of the finger or thumb that involves multiple septal compartments (FIG 1).
ANATOMY
The nail complex consists of the nail bed, nail plate, and perionychium (FIG 2).
The nail plate sits below the proximal nail fold.
The perionychium is the border tissue which surrounds the nail.
The eponychium is the tissue that attaches closely to the nail plate proximally, commonly referred to as the cuticle.
The nail folds consist of skin, which continues underneath the visible edges to form a protective barrier.
The pulp of each digit consists of multiple compartments separated by fibrous septa.
These vertical septa extend from the periosteum of the distal phalanx to the epidermis, lending structural support to the fingertip.
PATHOGENESIS
Acute paronychia results from the introduction of bacteria into the space between the nail fold and the nail plate, either proximally or laterally.
This commonly occurs as a result of a hangnail, nail biting, or an overzealous manicure.
Chronic paronychia results from colonization and infection by organisms that enter the space between the nail plate and the cuticle, eponychium, and nail fold.
This chronic infection and inflammation lead to fibrosis of the eponychium, which, in turn, leads to decreased vascularity of the dorsal nail fold.
This decreased vascularity predisposes to repeated bacterial insults, resulting in the characteristic clinical exacerbations.
Felons often result from penetrating trauma, or from bacterial inoculation through the exocrine sweat glands contained within the pulp.
Cellulitis and local inflammation lead to local ischemia, which, in the setting of the closed spaces defined by septa, leads to increased pressure.
Fat necrosis and abscess formation result from the increased pressure, which, in turn, causes a further increase in pressure, and, in effect, a compartment syndrome.
NATURAL HISTORY
If acute paronychia is left untreated, an early infection will turn into an abscess along the nail fold.
The abscess may then extend into the pulp space or into the eponychium and then to the opposite side of the nail.
Purulence at the base of the nail may cause ischemia of the germinal matrix, which then may lead to temporary or permanent nail growth arrest.
Herpetic whitlow improves without any intervention in approximately 3 weeks.
Many cases of herpetic whitlow are misdiagnosed as acute paronychia or felon.
FIG 1 • Felon in coronal and sagittal section.
FIG 2 • Anatomy of the nail complex.
Subsequent incision and drainage may lead to secondary bacterial infection.
Chronic paronychia are characterized by induration of the eponychium punctuated by episodes of swelling and drainage.
A felon, if left untreated, may lead to osteomyelitis or septic flexor tenosynovitis.
PATIENT HISTORY AND PHYSICAL FINDINGS
In acute paronychia, the patient will complain of swelling and pain immediately adjacent to the nail.
If an abscess has formed, there may be purulent drainage.
In chronic paronychia, the patient will present with a chronically indurated and rounded eponychium characterized by repeated episodes of inflammation and drainage.
Herpetic whitlow is characterized by pain and swelling followed by the appearance of multiple vesicular lesions.
The pain typically is out of proportion to the physical findings, and the fingertip is not tense (in contrast to a felon).
A patient with a felon will present with severe throbbing pain, swelling, and a tense fingertip pad.
A felon will not extend proximal to the distal interphalangeal (DIP) joint flexion crease unless it is associated with septic flexor tenosynovitis.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Radiographs are indicated to rule out osteomyelitis or if a foreign body is suspected.
The diagnosis of herpetic whitlow is confirmed by Tzanck smear, which will show multinucleated giant cells.
Patients suspected of having a systemic illness should have the appropriate laboratory workup.
DIFFERENTIAL DIAGNOSIS
Acute paronychia
Chronic paronychia
Herpetic whitlow
Felon
Osteomyelitis
Septic arthritis of the DIP joint
NONOPERATIVE MANAGEMENT
Acute paronychia may be treated with warm soaks and oral antibiotics if infection is caught early and if no significant abscess is present.
Herpetic whitlow is managed by keeping the hands clean to prevent bacterial superinfections; these lesions will resolve on their own.
Some recommend treatment with oral acyclovir, but multiple clinical trials have failed to show any definite benefit.
Nonoperative treatment has no role in the treatment of chronic paronychia unless there is a concomitant fungal infection that may benefit from medical therapy.
Given the rapid clinical progression of a felon, nonoperative treatment with antibiotics rarely will be successful, except in very early cases.
SURGICAL MANAGEMENT
If the abscess is superficial, drainage may sometimes be performed without anesthesia.
If the infection is more extensive or involves both sides of the nail, incision and drainage should be performed under digital nerve block.
Use lidocaine or a mixture of lidocaine and bupivacaine without epinephrine.
Instillation of the medication at the level of the distal metacarpal from dorsal to volar is the safest and best tolerated technique.
Chronic paronychia usually are treated with eponychial marsupialization.
Chronic paronychia associated with underlying fungal infections may be amenable to more standard surgical treatments as performed for acute paronychia after the fungal infection has been successfully treated medically.
Herpetic whitlow is treated with incision and drainage only if a bacterial superinfection has occurred.
Positioning
The patient is placed in the supine position with a standard hand table and either digital or forearm tourniquet.
Approach
The surgical approach is dictated by the location of the infection.
Infection under the nail plate will require elevation of part of the nail.
Infection under the eponychial fold will require elevation of the eponychium.
Infection into the pulp will require incision deep into the pulp space.
TECHNIQUES
INCISION AND DRAINAGE OF AN ACUTE PARONYCHIA
Single Incision
Use a no. 15 scalpel to incise into the paronychial sulcus, keeping the blade directed away from the nail bed (TECH FIG 1A).
If the abscess extends below the nail plate, then that portion of the nail is freed from the underlying bed, a longitudinal incision is made in the nail, and that section of the nail is removed in an atraumatic manner (TECH FIG 1B,C).
Alternatively, if the purulence extends into the pulp space, the perionychium may be incised peripheral and parallel to the nail sulcus (TECH FIG 1D,E).
If the abscess extends to the eponychium, the incision may be carried as far proximally as necessary; a portion of nail may then be removed if necessary.
Parallel Incisions
If the abscess involves the eponychium and is not completely decompressed with a single incision, a parallel incision may be made on the opposite paronychial sulcus. The entire eponychial fold is elevated, and the proximal third of the nail is excised (TECH FIG 2).
This is then irrigated and packed with gauze to prevent premature closure.
TECH FIG 1 • A. Incision to drain the paronychia. B,C. Incision and removal of a portion of the nail plate. D,E. Alternative incision to drain the paronychia.
TECH FIG 2 • Incision (A) and elevation of the eponychial fold (B,C) with removal of the proximal nail to decompress a proximal abscess. D. The wound is packed with gauze to prevent premature closure.
EPONYCHIAL MARSUPIALIZATION FOR A CHRONIC PARONYCHIA
Make a crescent-shaped incision 1 to 3 mm proximal to the eponychial fold, extending 3 to 5 mm proximally and extending to the edge of each nail fold (TECH FIG 3A,B).
Excise this tissue, taking care not to damage the underlying germinal matrix (TECH FIG 3C).
Irrigate and dress the wound appropriately.
Allow the wound to heal by secondary intention.
TECH FIG 3 • A,B. Incision for marsupialization of chronic paronychia. C. Tissue removed with the underlying germinal matrix exposed.
INCISION AND DRAINAGE OF A FELON
Base the incision over the point of maximal tenderness. Be aware that an incision on the pulp can result in a tender scar.
For a volarly oriented abscess, make an incision precisely in the midline distal to the DIP joint flexion crease (TECH FIG 4A,B).
When the point of maximal tenderness is on the side of the finger pulp, make the incision longitudinally, dorsal to the tactile surface of the finger, not more than 3 mm from the edge of the nail. A more volar incision risks damage to the digital nerve branches (TECH FIG 4C).
Carry the incision deep enough to disrupt all involved septa, or spread with a hemostat (TECH FIG 4D,E).
Irrigate the wound with normal saline.
Place a strip of gauze into the open wound to allow for drainage, and dress appropriately.
TECH FIG 4 • A. Midvolar approach for drainage of a felon. B. Spread deeply with a hemostat to disrupt all septa. C,D. Lateral incision for drainage of a felon. E. Spread deeply with a hemostat to disrupt all septa.
POSTOPERATIVE CARE
Acute paronychia and felons
Oral antibiotics should be started postoperatively.
Soaks in a dilute solution of either chlorhexidine or povidone-iodine may be started on postoperative day 2 and continued until wound healing is completed. The packing is removed when the soaks begin.
Begin early range-of-motion exercises to avoid stiffness.
Chronic paronychia
Oral antibiotics usually are not necessary.
Soaks in a dilute solution of either chlorhexidine or povidone-iodine may be started on postoperative day 2 and continued until wound healing is completed.
Correction of environmental factors or systemic illness is critical.
Begin early range-of-motion exercises to avoid stiffness.
COMPLICATIONS
Recurrent infection (systemic spread of the infection)
Incisional tenderness (pulp)
Digital nerve injury
Decreased sensation
Neuroma
Osteomyelitis
Nail plate deformity
REFERENCES
1. Kesson AM. Use of acyclovir in herpes simplex virus infections. J Paediatr Child Health 1998;34:9.
2. Bednar M, Lane L. Eponychial marsupialization and nail removal for surgical treatment of chronic paronychia. J Hand Surg Am 1991;16:314–317.
3. Gill J, Arlette J, Buchan K. Herpes simplex virus infection of the hand. Am J Med 1988; 84:89–93.
4. Jebson PJ. Infections of the fingertip: Paronychias and felons. Hand Clin 1998;12:547.
5. Canales FL, Newmeyer WL III, Kilgore ES Jr. The treatment of felons and paronychias. Hand Clin 1989;5:515–523.
6. Hausman MR, Lisser SP. Hand infections. Orthop Clin North Am 1992;23:171–185.