Nail Bed (Nailbed) Injury Management in the ED

To fully appreciate the consequences and treatment of nail bed (nailbed) injuries, reviewing the anatomy of the nail bed and the surrounding tissues is useful.[1, 9, 10, 11]

• Nail - Hard structure composed of desiccated, keratinized squamous cells

• Perionychium - Composed of the nai lbed and paronychia

• Nail bed - Soft tissue below the nail that is bound to the underlying periosteum of the distal phalanx and consists of the germinal and sterile matrix[11]

• Paronychia - Lateral nail folds

• Hyponychium - Junction between the nail bed and fingertip skin that contains large numbers of polymorphonuclear leukocytes and lymphocytes, which protect the subungual tissue from infection

• Nail fold - Holds the proximal nail

• Eponychium - Commonly known as the cuticle, or the distal portion of the nail fold where it attaches to the dorsum of the nail

• Lunula - White opacity distal to the eponychium, caused by the presence of nail cell nuclei in the germinal matrix as they stream upward and distally to create nail

Nail formation is a collective production by 3 areas of the perionychium, as follows:

• The germinal (intermediate) matrix, covering the ventral floor of the proximal volar nail fold to the lunula, produces 90% of nail volume. It is immediately distal to the extensor tendon attachment to the distal phalanx. As the cells are produced, they force cells ahead to flatten and stream distally into the nail because of the confining boundaries of the nail fold. The nuclei of the cells disintegrate as they grow beyond the lunula, giving the nail its clear appearance.

• The sterile (ventral) matrix begins as the lunula ends and extends out to the hyponychium. It is closely adherent to the dorsal periosteum of the distal phalanx. It contributes a small amount to the nail but mostly provides adherence between the nail and the nail bed.

• The proximal half of the dorsal roof of the nail fold produces cells that give the nail its shine.

Longitudinal nail growth takes between 70 and 160 days to cover the entire length of the nail. In general, a normal fingernail grows out completely in about 6 months, whereas toenails grow one-third to half the rate of fingernails; thus, toenails take 12-18 months to grow out entirely. The nail growth rate is less than normal in people who are immunocompromised, immobilized or paralyzed, malnourished, suffering from acute infection, or undergoing antimitotic drug therapy.[12]

After an injury, nail growth is stunted or absent for up to 21 days. The nail then grows rapidly for approximately the next 50 days and then slows again before a normal and sustained growth rate resumes. These relative accelerations and slowdowns in nail growth create the characteristic lump that is often observed on most nails that regrow after trauma.

As a result of scar tissue being unable to produce nail material, damage to specific components of the perionychium will lead to characteristic defects during regrowth of the posttraumatic nail. A scar of the dorsal roof of the nail fold creates a dull streak on the nail surface, while a scar of the germinal matrix may cause a split or absent nail, and a scar in the sterile matrix results in a split or nonadherent nail beyond the scar.

The nail bed is supplied by 2 volar arterial arches that are anastomoses between digital arteries of the finger or toe, just above the periosteum of the distal phalanx. Venous drainage coalesces in the proximal nail bed and proximal to the nail fold and drains over the dorsum of the finger. Abundant lymphatic vessels are present in the nail bed. The perionychium is innervated by the dorsal branches of the paired digital nerves, one to the nail fold, one to the fingertip, and one to the pulp.

The hand is involved in 11-14% of on-the-job injuries and 10% of all accident cases in US emergency departments. However, the exact prevalence of nail bed (nailbed) injuries is unknown, since many patients with nail bed injuries do not bother to seek a physician's care for what they perceive as a minor trauma.

Complications of nail bed injuries include nail loss, abnormal growth, nonadherence of new nail, splitting of the nail, soft tissue infection, and osteomyelitis of the underlying distal tuft.

There is a 3:1 male-to-female predominance of injury.

Nail bed injuries occur in people of all ages; however, the most common age group is between 4 and 30 years. Fingertip injuries account for two thirds of hand injuries in children, and damage to the nail bed occurs in 15-24% of these injuries.[2, 3]

In a retrospective study of 457 children with finger nail bed injuries, most repairs were found to have been done by the pediatric emergency physician (72.2%). Predictors of complications were type of injury (stellate laceration and severe crushed nail bed injuries) and fracture of the distal phalanx, and predictors of use of antibiotics were mechanism of injury (crushed in door, sports injury, and road traffic accident) and fracture of the distal phalanx.[13]  

A complete history for a nail bed (nailbed) injury should include hand dominance, time of the injury, the presence of an associated open wound, previous history of hand injury, tetanus status, occupation and hobbies, and the patient's overall health. All of these aspects of the patient's presentation may affect the treatment plan for the injury. Also, inquire about the circumstances of the accident, as the mechanism of injury has prognostic implications for severity of injury and wound contamination.

Most injuries of the nail bed involve the fingertip versus an isolated nail bed injury (6:1 ratio). The right and left hands are affected equally. However, the long finger is most often affected, since it is usually the last to be pulled from a situation that has the potential to cause trauma. After the long finger, the ring finger, index finger, pinky finger, and thumb are affected in that order. The middle and distal third of the nail are the most frequent sites of injury.

Crush and avulsion injuries, as well as injuries associated with distal phalanx fractures, have a worse prognosis. Injuries that span the entire nail bed or most of the bed and fold also fare worse than those that are isolated to one to two thirds of the nail bed or only to the nail fold and germinal matrix.

A general examination is necessary to rule out additional injuries.

The injured finger can usually be examined without anesthesia, although children or those in severe pain may require a digital block first. A complete sensory examination (performed prior to a digital block), as well as motor function and vascular supply, is necessary. If the nail is avulsed from the nail fold and is unstable, a digital block will usually be necessary to accurately examine the extent of injury. Loupe magnification may be used if necessary.

The presence and extent of devascularized and macerated skin should be noted as the presence of active bleeding, a subungual hematoma, avulsion of the nail, disruption of the nail bed, and any specific pattern of laceration (linear, stellate, flap) of the nail bed if visible. Observe the posture of the fingers, and look for any presence of deformities signifying fracture, dislocation, or tendon avulsion, as well as the presence of glass, wood, metal, or other foreign-body fragments.

Nail bed (nailbed) injuries are often accompanied by subungual hematomas, lacerations to the surrounding skin, crush or avulsion injuries to the distal finger, and associated fractures of the distal phalanx.

A subungual hematoma is a common presentation, and the possibility of an underlying nail bed laceration or injury should always be considered. Lacerations of the nail bed associated with subungual hematomas are most often stellate. Simple lacerations are uncommon unless an accompanying crushing component that was strong enough to collapse the nail through the nail bed and onto the distal phalanx or to fracture the distal phalanx occurred. Fracture of the distal phalanx usually disrupts the matrix but may not break the nail.

The nail may also be partially or completely avulsed from the nail fold. Nail plate avulsion is almost invariably accompanied by significant nail bed laceration that requires repair. Fractures of the distal phalanx are present in 50% of nail bed injuries.[14]

A Seymour fracture is an injury unique to children and requires prompt attention. Following crush injury or axial load, an angulated Salter-Harris type I or II fracture of the distal phalanx with an associated nail bed injury might result. The nail plate is typically avulsed proximally from the nail fold, and soft tissue (often the germinal matrix of the nail) might become interposed in the fracture, preventing reduction and healing. The typical presentation is a swollen, ecchymosed, and painful finger that is flexed at the distal interphalangeal joint (DIPJ).[15]

Depending on the extent of injury, radiologic evaluation with anteroposterior, lateral, and oblique views of the injured finger(s) may be useful to rule out foreign bodies and fractures or dislocations of the distal finger.[6]

In a study of children with nail bed (nailbed) injuries, the authors found that 50% of their patients had an associated distal phalangeal fracture, most often a comminuted tuft fracture.[16] Most tuft fractures, in the setting of a nail bed injury, require no specific treatment outside of addressing the nail bed injury and protective splinting. Transverse shaft fractures that are significantly displaced may require surgical repair.[17]

In a study utilizing point-of-care ultrasound in patients presenting to the ED with distal finger trauma, sensitivity was 93.4% and specificity was 100% for diagnosing nail bed injury.[18]

Subungual hematoma

Small (less than 25% of the nail bed [nailbed]) and painless subungual hematomas require no intervention, as the hematoma will eventually reabsorb. If the subungual hematoma covers more than 25% of the nail bed or is causing pain, the patient should be offered evacuation via trephination or nail removal.

Treatment of subungual hematomas covering greater than 25-50% of the nail bed is controversial and varies with personal preference.[19] Historically, treatment includes removal of the nail and repair of any underlying lacerations. This practice came about because 50% of these hematomas have concurrent nail bed lacerations. The incidence of nail bed laceration increases to 94% when associated with a distal phalangeal fracture, regardless of the size of the hematoma.[4, 20, 21, 22, 23]

Studies have shown that as long as the nail is still partially adherent to the nail bed or paronychia and is not displaced out of the nail fold, removal of the nail and repair of the nail bed does not improve outcomes versus simple trephination. Neither the size of the hematoma nor the presence of an associated fracture has been associated with adverse outcomes.[16, 24, 25] Trephination is contraindicated if a fracture requires surgical repair or if the germinal matrix is entrapped within the fracture, as delayed union or the formation of an intraosseous inclusion cyst may occur.[17]

The advantages of simple trephination include less pain for the patient, shorter length of stay, and less costly intervention.[16]

Evacuation of hematomas

Various methods of trephination exist (shown in the image below). The easiest and safest is to use an electric cautery, which melts a hole through the nail. Once the cautery encounters the underlying hematoma, the tip cools, preventing further injury to the nail bed. If the hole is of adequate size, blood will drain and relieve some pain and the pressure sensation for the patient.

A paper clip may also be used after it is heated until red hot.[26]

An 18-gauge needle may be used by twirling the needle back and forth with slight downward pressure until dark blood return is noted. Use of an 18-gauge needle is less optimal because of the risk of injury to the nail bed once the nail has been penetrated. Alternatively, the needle may be directed at an oblique angle (45-60°) without applying pressure.[27]

Another technique is use of a sterile 29-gauge extra-fine insulin syringe needle.[28] Instead of penetrating the nail, the needle is inserted at the hyponychium parallel to the nail, aimed at the most distal portion of the hematoma. Care is taken to keep the needle closer to the nail versus the nail bed. Once the hematoma is penetrated, the needle may be withdrawn. and light pressure placed on the nail will help with evacuation of the hematoma. This technique may obviate the need for digital block anesthesia and may be favorable in evacuating hematomas of the smaller toe nail beds, where trephination is more difficult.

The use of a 2- or 3-mm biopsy punch has also been described.[29, 30] The biopsy punch is gently twirled back and forth with minimal pressure over the hematoma.

Nail bed repair

Principles of treatment include minimal debridement, preservation of as much tissue as possible, atraumatic wound care, and splinting with the nail or an alternative material.[31, 32, 13] (Nail bed repair is shown in the image below.)

 

A digital block of 1% lidocaine hydrochloride without epinephrine provides anesthesia of sufficient duration for most repairs. Bupivacaine extends anesthesia time 4-8 hours for longer procedures.

Children may require procedural sedation and analgesia.

The hand should be prepared with povidone-iodine (Betadine) and covered with sterile drapes. The injured finger should be exsanguinated with a half-inch or 1-inch Penrose drain wrapped in a distal to proximal direction and placed around the base to serve as a tourniquet and provide a blood-free field.

The nail is elevated using the blades of either fine or curved iris scissors or small elevator scissors. Specific care is necessary to not injure the nail bed. A blunt dissecting technique should be used, and the scissors are placed gently underneath the nail until they reach the nail fold. Slowly open the scissors as it is removed. Care must again be taken to avoid further damage to the underlying nail bed or overlying nail fold. Once the nail is sufficiently separated from the nail bed, it is gently removed by applying firm and steady distal traction using a hemostat.

Lacerations to the nail bed should be repaired using 6-0 or smaller absorbable sutures. Minimal to no debridement should be performed because aggressive debridement may cause undue tension on the repair and results in scarring.

When repairing avulsed nails and nail beds, if the nail is detached proximally, it must be removed to inspect for any damage to the nail bed. Careful inspection of the nail is important because often only a fragment of nail bed may be attached to the undersurface of the avulsed nail. Only outer and dorsal surfaces of the nail should be cleaned. Any large fragments of nail bed should be preserved for use as a free graft. Crushing injuries leave many small pieces of nail bed. If all fragments are not incorporated into the repair, they may grow independently and cause nail horns or spicules. If tissue is not available and the defect is small enough, the area will heal effectively by secondary intention.

Simple dorsal roof lacerations can often be repaired by accurately repairing the skin overlying the nail fold. However, if possible, suturing of the dorsal roof with a 7-0 chromic suture may provide more accurate repair. Associated paronychial injuries must be repaired and stented to prevent pterygium or adhesions, as it serves as a mold to coax nail to grow along a proper path. Distal phalangeal fracture reduction and healing is important to final nail formation. Poor reduction of the bone translates directly into irregularities of the nail bed.

The proximal nail should be reinserted into the nail fold. The replaced nail keeps the nail fold open for new nail growth and provides a protective cover for the nail bed and a precise template for new nail to follow as it regenerates. It also serves as a rigid splint for any underlying fractures and reduces postoperative discomfort and improves postoperative function. Some evidence suggests, though, that replacing the nail may be unnecessary[33] and may delay wound healing and increase the risk of infection in children.[34, 35]

Before replacement, a small hole should be made in the nail, preferably so that it is not overlying the laceration. This is to allow drainage and thus prevent a growing hematoma to separate the nail from the nail bed.

The nail is then placed back in the nail fold as a stent and held in position by 5-0 or smaller nylon sutures placed by one or a combination of the techniques below:

• Distally through the hyponychium and the nail.

• Through the nail and proximal to the nail fold.[36]

• Through a half-buried horizontal mattress suture placed down proximal to the nail fold into proximal nail then back out the nail fold.

• Through the paronychia and nail bilaterally.

• As a dorsal figure-of-eight suture[37] : A suture is placed transversely just distal to the hyponychium, then placed proximal to the nail fold in the same direction and tied back to itself. If the nail slips laterally, 2 small vertical cuts may be made in the nail for the suture to catch upon.

• An alternative figure-of-eight suture ^[38] : A suture is placed along one paronychium for approximately 5 mm, then taken over the nail and sutured along the opposite paronychium in the same direction as the first suture, such that the sutures cross over the nail.

• Utilizing a double stitch[38] : A combination of both-described figure-of-eight sutures, without necessarily having to create a figure-of-eight suture with each stitch. A suture is placed along one paronychium for approximately 5 mm, then taken over the nail and sutured along the opposite paronychium in the opposite direction as the first suture and tied over the nail. A second suture is then placed proximal to the eponychium and taken over the nail plate through the fingertip just distal to the hyponychium and tied off. 

• In lieu of sutures, tissue adhesives such as Indermil (n- butyl cyanoacrylate) or Dermabond (octyl-2-cyanoacrylate) may be applied along the perionychium after the nail is replaced.[39] Tissue adhesives are also a less invasive option for nail bed and nail repair.[40]

  • In one randomized controlled trial, nail bed laceration repair using Dermabond required less time with no difference in cosmetic or functional outcomes compared to suture repair.[41] The adhesive should be allowed to dry prior to replacing the nail.

  • Nail fragments may be repaired together first using adhesive, then secured into the nail fold by a thin layer placed under the nail, using gentle downward pressure while the adhesive dries.[42]

  • Alternatively, nail fragments may be pieced together on the nail bed, with a light coating of adhesive wiped or dripped between adjoining fragments and on skin adjacent to the perimeter of the nail. As the adhesive dries, use forceps to maintain external pressure.[43]

  • Chloramphenicol ointment may be used in a similar fashion for simple lacerations, with a small amount applied under the nail so that the ointment forms an adhesive layer as it is positioned into the nail fold.[44]

• If the original nail is missing, nonadherent gauze, aluminum suture package material, 0.020-inch reinforced silicone sheeting, acrylic (artificial) nail,[45]  or splints made from hypodermic syringes[46] or nasogastric tubing[47] may be used as the splint in place of the nail.

• Dress the injured finger with nonadherent gauze and 2-inch gauze roll, then splint the finger.

A hand surgeon should be consulted for significantly avulsed nail matrix or for severe crush injuries.

In general, except for a simple subungual hematoma in which the nail bed was not inspected for potential laceration or injury, a wound check in 2-5 days is suggested to check for infection and to repack the nail fold, if necessary. Sutures should be removed from any replaced nail in approximately 2-3 weeks. If acrylic nail, hypodermic syringe sheath, or other material was used as a stent, it should be removed in 3 weeks. If the original nail was used as a splint, it will be pushed out as new nail grows in, and it will fall out on its own.

In a study by Chiche et al, glue (2-octylcyanoacrylate) and absorbable sutures were compared for nail bed repair in children (74 nail bed lacerations in 68 children). In the study, 36 nail beds were repaired with glue in the ED versus 38 sutured in the operating room. The rate of nail dystrophy was 14% (5% major) regardless of the technique used, but time of nail bed repair was significantly shorter in the ED glue group (10.2 vs. 20.3 min, P< 0.001). The complication rate was higher for patients treated in the ED.[32]

Small (less than 25% of the nail bed) and painless subungual hematomas require no intervention, as the hematoma will eventually reabsorb. If the subungual hematoma covers more than 25% of the nail bed or is causing pain, the patient should be offered evacuation via trephination or nail removal.

Treatment of subungual hematomas covering greater than 25-50% of the nail bed is controversial and varies with personal preference.[4, 20, 21, 22, 23, 19]

Some studies have concluded that as long as the nail is still partially adherent to the nail bed or paronychia and is not displaced out of the nail fold, removal of the nail and repair of the nail bed do not improve outcomes versus simple trephination. Neither the size of the hematoma nor the presence of an associated fracture has been associated with adverse outcomes.[16, 24, 25] Trephination is contraindicated if a fracture requires surgical repair or if the germinal matrix is entrapped within the fracture, as delayed union or the formation of an intraosseous inclusion cyst may occur.[17]

Lacerations to the nail bed should be repaired using 6-0 or smaller absorbable sutures. Minimal to no debridement should be performed because aggressive debridement may cause undue tension on the repair and results in scarring. Tissue adhesives are also a less invasive option for nail bed and nail repair.[40]

When repairing avulsed nails and nail beds, if the nail is detached proximally, it must be removed to inspect for any damage to the nail bed.

A new prospective surgical approach has been discussed for large-area defects of the nail bed with distal phalanx exposure, which is a cross finger fascial flap combined with thin split-thickness toe nail bed graft.[48]

Cosmetic surgery: medical tattooing

Medical tattooing is used to restore part of a patient’s physical integrity and may assist in psychological recovery from the physical and/or psychological consequences of disease, surgery, or trauma. Successful application to simulate reconstruction of the nail bed after removal through a surgical avulsion procedure has been reported.[49]

The goal of pharmacotherapy is to reduce pain and to prevent infection. If not updated, tetanus immunization is indicated.

Class Summary

Therapy must cover all likely pathogens in the context of the clinical setting. The prophylactic use of antibiotics is indicated depending on mechanism and extent of injury, such as for crush injuries and human or animal bites. Although the benefit of prophylactic antibiotics has not been proven, even if an open fracture of the distal phalanx is present, to be safe many clinicians still prescribe a first-generation cephalosporin when bone or joint are exposed below a nailbed injury. A large, randomized controlled study may be necessary in the future to examine the utility of antibiotics in such circumstances.

Cephalexin (Keflex, Biocef)

First-generation cephalosporin that inhibits bacterial growth by inhibiting bacterial cell wall synthesis. Bactericidal and effective against rapidly growing organisms forming cell walls. Acceptable alternative to penicillin and may be useful in patients with minor penicillin allergies.

Class Summary

NSAIDs are commonly used for relief of mild to moderate pain. Effects of NSAIDs in treating pain tend to be patient specific, but ibuprofen is usually the drug of choice (DOC) for initial therapy. Other options include ketoprofen, flurbiprofen, and naproxen.

Ibuprofen (Ibuprin, Advil, Motrin)

Usually DOC for treatment of mild to moderate pain if no contraindications exist. Decreases inflammatory reactions and pain by inhibiting the activity of the enzyme cyclooxygenase, resulting in diminished prostaglandin synthesis.

Flurbiprofen (Ansaid)

Has analgesic, antipyretic, and anti-inflammatory effects. Decreases inflammatory reactions and pain by inhibiting the activity of the enzyme cyclooxygenase, resulting in diminished prostaglandin synthesis.

Ketoprofen (Oruvail, Orudis, Actron)

Used for relief of mild to moderate pain and inflammation. For patients with a small body size, elderly persons, and those with renal or liver disease, initially administer small dosages. Doses >75 mg do not increase therapeutic effects. Administer high doses with caution and closely observe patients' responses.

Naproxen (Anaprox, Naprelan, Naprosyn)

Used for relief of mild to moderate pain. Decreases inflammatory reactions and pain by inhibiting the activity of the enzyme cyclooxygenase, resulting in diminished prostaglandin synthesis.

Class Summary

These agents are reserved for those with moderate to severe pain.  They should be prescribed in the setting of those who have contraindications to NSAIDS, or for breakthrough pain while using NSAIDS.  Current practice dictates a short course of use.

 

Acetaminophen (Tylenol, Panadol, Aspirin-free Anacin)

DOC for pain in patients with documented hypersensitivity to aspirin or NSAIDs, with upper GI disease, or who are taking oral anticoagulants.

Acetaminophen and codeine (Tylenol #3)

Drug combination indicated for treatment of mild to moderate pain.

Hydrocodone bitartrate and acetaminophen (Vicodin, Norco)

Drug combination indicated for the relief of moderate to severe pain.

Oxycodone and acetaminophen (Percocet)

Drug combination indicated for the relief of moderate to severe pain. DOC for aspirin-hypersensitive patients.

Class Summary

This agent is used for tetanus immunization. Administer booster injection in previously immunized individuals to prevent this potentially lethal syndrome.

Tetanus toxoid adsorbed or fluid

Used to induce active immunity against tetanus in selected patients. The immunizing agent of choice for most adults and children aged > 7 y are tetanus and diphtheria toxoids. Necessary to administer booster doses to maintain tetanus immunity throughout life. Pregnant patients should receive only tetanus toxoid, not a diphtheria antigen-containing product. May administer into deltoid or midlateral thigh muscles in children and adults. In infants, preferred site of administration is the mid thigh laterally.

Class Summary

Patients who may not have been immunized against Clostridium tetani products should receive tetanus immune globulin (Hyper-Tet).

Tetanus immune globulin (TIG)

Used for passive immunization of persons with wounds that may be contaminated with tetanus spores.