Approach to nail trauma for primary care physicians

Case description

A 38-year-old, right hand–dominant patient who works as a landscaper presents to your walk-in clinic after sustaining a direct blow to his left index finger from a hammer while on the job. He describes persistent throbbing pain localized to the nail. Upon examination, you find range of motion is intact, though limited by pain, and neurovascular examination results are normal. However, you note blood under the nail plate, which is falling off (Figure 1). How would you approach this injury?

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Figure 1.

Fingernail injury

Sources of information

An Ovid MEDLINE literature search was performed using search terms nail trauma, nail malignancy, nail reconstruction, nail infection, and Seymour fractures. Studies were graded based on level of evidence: level I for randomized controlled trials or systematic reviews, level II for other comparison trials, and level III for evidence based on expert opinion or consensus.

Main message

Relevant anatomy. The fingernail is a key component of the fingertip and provides essential functions such as protecting the dorsal surface, acting as counterforce, increasing the sense of touch, and facilitating fine movements.¹ The nail plate is made of keratin and adheres to the underlying nail bed. The latter comprises the proximal germinal matrix, responsible for nail formation, and the distal sterile matrix (a secondary site for nail production), responsible for nail adherence. The dorsal roof of the nail fold gives the nail its shiny appearance. The eponychium is the proximal nail fold, the paronychium corresponds to the lateral nail folds, and the hyponychium refers to the pulp under the distal free edge of the nail. Fingernail growth rate is approximately 0.1 mm per day, though it varies by age and gender.^2,3 Fingertip and nail anatomy are illustrated in Figure 2.

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Figure 2.

Diagram of fingertip and nail anatomy

Clinical evaluation. Taking a thorough history and performing a physical examination are the first steps in assessing any hand injury. The standard approach involves documenting the patient’s age; hand dominance; occupation; the time, place, and mechanism of injury; degree of contamination; and any previously attempted treatments. Other key questions include tetanus status and risk factors for abnormal wound healing, such as diabetes, immunosuppression, and smoking. Physical examination begins with inspection for skin changes, abnormal finger cascade, scissoring, or bony deformities. The degree and location of any swelling, bruising, lacerations, or other open injuries should be documented. Specific to the fingertip, it is vital to note the status of the nail plate and whether it is positioned appropriately under the eponychial fold. A comprehensive neurovascular examination should be performed by assessing pulp capillary refill, performing 2-point discrimination, and comparing with an uninjured digit. Active and passive range of motion should be assessed, too.

Clinical evaluation of nail bed injuries may require local anesthesia through a digital block. Tourniquet control may aid visualization by creating a bloodless field. Many commercial digital tourniquets are available off the shelf. Alternatively, one could quickly improvise with the glove technique,⁴ which consists of a patient wearing a standard medical glove, cutting a small hole in the glove at the top of the affected finger, and, with the hand held up above the level of the heart, rolling the remaining material down the finger, exsanguinating it. An inventory of injured structures should be made. Diagrams and schematics are often more descriptive than words for documentation. Plain film x-ray scans should be ordered, as 50% of nail bed injuries are associated with an underlying distal phalanx (DP) fracture.⁵

Nail bed trauma pathology. Nail bed injuries can present differently. Subungual hematomas represent the simplest type of nail bed injury and develop from nail bed lacerations. As the tight space of the nail bed can hardly accommodate an increase in volume, the resulting pressure translates into throbbing pain. Observation is sufficient in asymptomatic patients. However, hematoma evacuation through trephination is indicated for relief of moderate to severe pain. The most common technique for trephination is Bovie electrocautery. Alternatively, one could heat up a paper clip until it is incandescent. Simpler methods of boring with a 23-gauge double-bevel needle have been described: with a needle held between the thumb and the third finger, and stabilized by the index finger at the thumb, one can rotate the needle like a drill to penetrate the nail.⁶ The technique is typically painless, but patients with an associated DP fracture may require local anesthetic; nevertheless, nail deformities resulting from such injury remain rare.

Nail plate removal and nail bed repair remain controversial. It was previously common practice to explore the nail bed with large hematomas composing more than 50% of the nail bed by removing the nail, adjacent debris, or devitalized tissue and irrigating with sterile technique. A landmark paper examining aesthetic outcomes in children with subungual hematoma treated with trephination versus nail plate removal and nail bed repair demonstrated no notable difference in outcomes.⁷ During a follow-up period of 13 to 37 months, complications such as nail depression, hypertrophy, or leukonychia were seen in 4 out of 26 operated fingers versus only 1 (nail depression) out of 27 non-operated fingers. All were transient apart from the leukonychia. There were no infections. Several other studies and guidelines support trephination alone for subungual hematoma of any size when the nail plate is adherent to the nail bed, without any appreciable nail lacerations (level II evidence).^8-11

Note that 50% of nail bed injuries have an accompanying DP fracture.⁵ Nondisplaced fractures are managed expectantly, while tuft and nondisplaced DP fractures may require nail bed repair and nail plate splinting. Comminuted DP fractures may require closed reduction and nail plate splinting. More proximal DP fractures are frequently reduced and stabilized using crossed Kirschner wires without crossing the distal interphalangeal joint, but treatment is dependent on the clinical context.⁵ As such, refer patients with displaced DP fractures to the emergency department (ED) or nearest hand surgeon.

Seymour fractures are open, displaced DP fractures involving the growth plate, where the nail bed gets trapped within the growth plate. These fractures are rare, representing 5.4% of all pediatric DP fractures presenting to a single institution.¹² However, they have a high risk of complications when missed, including osteomyelitis, and substantial morbidity from growth arrest or persistent deformity. Consider this diagnosis when a child presents with a mallet finger deformity where the base of the nail plate is avulsed superficially from the proximal nail fold. Confirming the diagnosis with a lateral radiograph would show a fracture at the physis and volar angulation of the diaphysis. Seymour fractures are managed through nail bed reduction and repair, fracture reduction, and nail plate replacement.^12,13

More severe nail bed injuries can have fragmentation or avulsion of the nail bed. They often occur from injury to the germinal matrix.⁵ These injuries should urgently be referred to the ED for repair, where avulsed nail fragments can be used as full-thickness grafts.

Nail bed repair. For subungual hematomas, nail plate removal and nail bed exploration are not indicated with an intact nail plate and distal edge (level II evidence).^7-11 However, exploration and repair are indicated for any associated nail plate injury, a proximal fracture involving the germinal matrix, and DP fracture requiring stabilization (level III evidence).^8,14 Before attempting nail plate removal, administer local anesthetic and apply a tourniquet. For removal, enter the hyponychium with curved scissors (concave side down), and gently release the nail by repeatedly spreading the scissors, staying just under the plate, until the lateral margins and eponychium are reached. Once freed, the nail can be pulled off by clamping the nail plate within a hemostat gripped just proximal to the nail fold. Nail bed repair can be undertaken with absorbable sutures (eg, 5-0 plain gut). However, dermal adhesive has been shown to have equivalent aesthetic outcomes and requires less operative time (level I evidence).¹⁵ Treatment can be conducted in an ED, minor surgery clinic, or operating room, depending on concomitant unstable DP fractures and local practice guidelines.⁸ Following treatment, the original nail plate can be reapplied, acting like a splint, to protect the repair site and prevent adhesions between the nail fold and nail bed. Bristol and Verchere described a transverse figure-of-eight suture technique for securing the native nail plate back in its anatomical position and preventing distal or dorsal movement.¹⁶ Alternatively, if the original nail is damaged or lost, a foil suture package can be trimmed to the shape of a nail plate, slid under the eponychium, and secured to the nail bed with a plain gut suture. Nevertheless, not replacing the nail plate (or suture package) has not been shown to adversely affect nail regrowth or appearance (level II evidence).¹⁷ After a nail is discarded, regrowth starts after 3 weeks and requires 70 to 160 days.⁷

Complications. Secondary nail deformities result from a problem at the site of nail production or nail support. The best functional and aesthetic outcomes result from the initial nail bed repair, with well-approximated lacerations.¹⁸ Secondary nail deformities include nail plate ridging from an uneven nail support site (DP), nail splitting from matrix scarring, nail absence from matrix destruction, nail hooking, nail cysts and spikes, pincer nail, nonadherence, and pterygium (webbing between the nail fold and plate). Predictors for complications include nail bed injuries associated with crush injury and with fractures.¹⁹ Given the slow nail growth rate, the result may not be apparent for up to 6 months. Patients should be referred to a plastic surgeon for nail bed lacerations or fractures, as revision procedures might be required.

Case resolution

You determine the landscaper’s presentation is in keeping with a nail bed injury. You instruct him to present to the nearest ED, where an x-ray scan rules out a fracture. Under digital block and tourniquet control, the nail plate is removed, and the nail bed is examined for lacerations (Figures 1 and 3). Minimal debridement is undertaken, and simple or stellate lacerations are repaired using a 5-0 absorbable suture, such as plain gut (Figure 4). Alternatively, dermal adhesive can be used to shorten operative time. Nail bed repair protection is achieved by replacing the native nail 2 to 3 mm deep into the eponychial fold, which would also act as a splint if there were an underlying fracture (Figure 5); if the native nail had not been available or had been too damaged, a silicone sheet or foil from a suture package could have been used. The nail plate is secured into the eponychial fold with a 5-0 chromic gut suture (a dermal adhesive could be used as an alternative), following Bristol and Verchere’s transverse figure-of-eight suture technique (Figure 6).¹⁶ The patient is given these instructions following repair: wash fingertip daily with soap and water and cover with a small dry dressing; practise active range of motion of the distal interphalangeal joint; and do not take antibiotic medications unless prescribed by the physician. The patient is referred to hand therapy for compression, range-of-motion exercises, and desensitization and is advised to follow up with the surgeon in 3 to 4 weeks.

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Figure 3.

Nail bed examination for lacerations

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Figure 4.

Nail bed debridement and suturing

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Figure 5.

Replacement of native nail 2 to 3 mm deep into eponychial fold

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Figure 6.

Nail plate secured using a 5-0 chromic gut suture by following figure-of-eight suture technique