Acute Paronychia

Last updated on April 14, 2020

Overview

The importance of adequately treating hand infections must not be understated. Sequelae from these injuries if unresolved can result in stiffness, deformity, functional disability, contracture, and even amputation. Paronychia is considered to be the most common infection of the hand.^1,2 Acute paronychia is a perionychial or eponychial infection that involves an abscess. The affected nail fold is seeded by bacteria from mechanical trauma. Commonly, nail biting, manipulation with manicure tools, or hang nails can all be a nidus for infection. Oftentimes the offending agent is mixed flora, but S. aureus is the most common isolated organism. ^3,4

Anatomy

The nail complex has distinct landmarks that are crucial to understand when treating infections and injuries to this area. The perionychium includes the nail matrix, eponychium, nail fold, nail plate, hyponychium and the paronychium. The paronychium consist of the skin on the lateral aspects of the nail, while the eponychium is the skin most proximal to the nail fold. The nail matrix is divided into the germinal and sterile matrix, which are separated by a white arc known as the lunula. Proximally, the germinal matrix is responsible for 90% of the fingers nail production. Distally, the sterile matrix is where the nail plate densely adheres and also provides some nail formation. Even further distally is the hyponychium, which is where the sterile matrix meets skin at the tip of the finger.^5,6Acute paronychia is an infection that can involve all soft tissue structures around the nail plate itself. Figures 1a and 1b serve as an anatomic reference.

**Figure 1a.** Anatomic landmarks of the nail plate also demonstrating a potential space for infection to occur.
Illustration by Craig Moores licensed under CC BY-NC-SA 4.0

**Figure 1b.** Anatomic landmarks of the finger tip and nail plate on sagittal view.
Illustration by Craig Moores licensed under CC BY-NC-SA 4.0

Presentation

Patients with acute paronychia will present initially with swelling, redness, and tenderness surrounding the nail. These early presentations can be treated with soaks and antibiotic therapy. However, intervention is required when there is abscess formation. These collections generally occur within the nail fold can after prolonged infection. The abscess can extend under the nail plate and in rare cases spread lateral and volar into the finger pulp creating a felon. Initial radiographs are not typically necessary and standard infectious work up can be done instead. Hand dominance, progression/timing of disease, and presence of an inciting event are all important for documentation when first meeting the patient. A case example is described in Figure 2.

**Figure 2.** 66 year old right handed male who presented with left middle finger infection. He stated that he was trimming his nails a week prior, and cut himself. Since then, the finger became more swollen and painful. He tried to drain it himself.
Image by Martin Carney licensed under CC BY-NC-SA 4.0

Treatment

After initial failed conservative treatment, intervention is warranted to adequately resolve infection. Local anesthesia with a digital block using plain lidocaine is recommended. Infection must be cleared from the nail fold through sharp incision, with the blade ideally remaining away from the nail bed and matrix. The incision must still be deep enough to fully drain the pus. If infection is located underneath the nail plate, partial and oftentimes full nail removal must occur. A freer and even small scissors can be used to remove the nail, while using care to not plunge into the nail bed or matrix. If possible, a culture should also be collected prior to initiating antibiotic therapy. Infected tissue and collections must be adequately debrided and incised. Next thorough irrigation and warm soaks should begin twice daily. Patients can be discharged with a dry sterile dressing using bacitracin and xeroform over the nail bed. Oral antibiotics also should be prescribed for 5-7 days. Post-procedural pictures and description are shown in Figure 3. Other potential sites for drainage are illustrated in Figure 4.

**Figure 3.** Patient 1 week after removal of nail and debridement of necrotic tissue. The skin re-epithelialized, and the nail grew out normally.
Image by Martin Carney licensed under CC BY-NC-SA 4.0

**Figure 4.** Alternate incision patterns for nail sparing treatment of acute paronychia.
Illustration by Craig Moores licensed under CC BY-NC-SA 4.0

Consult summary/Pearls

Acute paronychia is one of the most common hand infections and will certainly be encountered by the consult resident. Taking a complete history, and performing thorough examination and treatment is paramount to adequately treating the patient. If the nail is affected, it must be removed, at least partially. The patient should go home with post-procedural antibiotics and immediately start hydrotherapy twice daily. The most commonly isolated organism is S. aureus.