Nail Bed Injury
Andrew D. Sobel
Fingertip injuries, and injuries to the nail bed specifically, are common problems that vary widely in mechanism and severity. Injuries to the nail can involve any combination of the nail plate, nail bed, germinal matrix, eponychium, or bone of the distal phalanx. Nail bed injuries in the pediatric population may have different management than those in the adult population, depending on a variety of factors including involvement of the growth plate. Proper evaluation and identification of the injury and timely management is critical to preventing a painful, sensitive, or cosmetically unappealing outcome.
Perionychium3—the nail and its surrounding structures
Made of onchyn, a keratin-like material
Protects the nail bed and distal tissue. Improves sensory feedback of the fingertip
Fold of tissue dorsally and proximally over nail
Serves to smooth the nail plate as it grows
Contains one to two layers of germinal cells that contribute to nail plate thickness as it grows and moves distally
White arc on the proximal nail
Nail bed distal to the lunula is the sterile matrix; proximal to and including the lunula is the germinal matrix
Extends from ventral floor to lunula. Immediately superficial to distal phalanx periosteum
▲ Three to four germ cell layers thick. Produces 90% of the nail plate volume through “gradient parakeratosis”
Contributes to the nail plate formation. Source of shiny quality of nail plate
Site at which the sterile matrix stops and epithelial skin starts at the distal tip. A keratin plug at this site acts as a barrier between the nail and sterile matrix to prevent contamination/infection
Folds of skin on sides of nail that can tear (“hangnail”) and become infected (“paronychia”)
Distributes force placed on the palmar finger
Contains sensory receptors such as Pacinian and Meissner corpuscles, Merkel cell-neurite complexes
Extensor tendon (terminal slip)
Inserts approximately 2 mm proximal to the germinal matrix on the distal phalanx
Flexor digitorum profundus (FDP) tendon
Inserts on the distal phalanx just proximal to the distal palmar digital arterial anastomosis
Dorsal vein—overlies the distal phalanx and is important for anastomosis in amputations
Digital arteries—send major branches to the pulp, paronychium, and nail fold. Smaller branches go to the nail bed
Digital nerves send branches to the paronychium, pulp, and fingertip
Located palmar to the digital arteries
Mechanism of injury6
Most common mechanism for nail bed injuries
Nail bed avulsions with the loss of matrix tissue result in some of the worst outcomes as they often result in permanent deformity.
Fingertip avulsion (including the nail bed) may result in a more proximal injury as tension can be placed on the neurovascular structures.
Historically occur more commonly in men, likely due to occupational hazards
Powered hand tools or fixed powered machines are the top contributors to fingertip injuries in industries such as agriculture, manufacturing, and construction.9
Injuries at home in patients >15 years old are also typically caused by power tools (power saws, lawn mowers, snow blowers, etc.).10
The middle finger is most commonly injured as are the distal and middle portions of the nail bed because these are the most exposed/unprotected by the rest of the hand.
Nail bed injury present in 15% to 24% of fingertip injuries in children
Highest incidence in children <5 years old
Most commonly caused by jamming or crushing finger in a door
The middle finger and distal nail bed are most commonly injured.
Patient-related factors are important to determine the need and amount of intervention
Involvement of chemicals, toxic substances, electricity
Timing of injury
In the setting of active bleeding inadequately managed by compression alone, visualization may be improved by the placement of a tourniquet proximally on the digit or an inflated blood pressure cuff on the arm or forearm. It is crucial to remove this when control of bleeding is obtained to prevent ischemia.
Integrity of nail plate. Eponychial hematomas suggest avulsions of the plate at that site.
Nail bed/subungual hematoma
If hematoma takes up >50% nail bed surface area, there is a 60% chance of a laceration to the nail bed requiring repair.14
Injury pattern to the nail bed (avulsion and/or tissue loss vs other types amenable to direct repair)
In pediatrics, evaluate for avulsion of the proximal nail bed (Figure 52.3A)
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