Nail Bed Injuries

Nail Bed Injuries 

• The goal of treatment of nail bed injuries is to restore anatomy which will allow return of function and maximize cosmetic result.
• •Anatomy and physiology
  • •The germinal matrix, sterile matrix, and dorsal nail bed make up the nail bed.
    • •Germinal matrix: specialized cells that generate the majority of the nail plate; located proximal to the lunula
    • •Sterile matrix: contributes to the nail bed; located distal to the germinal matrix, acts to promote nail plate adherence to the nail bed
    • •Dorsal nail bed: gives the nail plate its hard, shiny coat

• Nail plate: the “nail”
• •Lunula: curved white portion of the proximal nail plate; overlies the distal portion of the germinal matrix
• •Eponychium: thin layer of skin that extends over the dorsal nail bed and nail plate, forms the nail fold
• •Perionychium: the folds of skin alongside of the nail plate
• •Hyponychium: the area between the distal nail plate and skin of the fingertip that acts as a barrier to infection
• •Nerve supply to perionychium via dorsal branches of the volar digital nerves
• •Arterial supply to the nail via two dorsal branches of the volar digital arteries
• •Four primary functions of the fingernail
  • •Protection of the fingertip
  • •Improved tactile sensation (counterforce)
  • •Regulation of peripheral circulation
  • •Assist in picking up objects
• •The nail plate grows an average of 0.1 mm/day or 100 days for complete growth, but distal growth is halted for 3 weeks as the proximal nail thickens.

History

• •Most nail bed injuries occur in children and adolescence.
• •Long finger is the most commonly involved digit.
• •Mechanism of injury: usually result of a crush or pinching type mechanism.
  • •Crush injury to the fingertip results in a compression of the nail bed between the nail and underlying bone, often creating a linear, stellate, or tearing laceration or avulsion injuries of the nail bed.
  • •Penetrating injuries through the nail plate result in linear lacerations of the nail bed at the same level.
• •Determine when the injury occurred.
• •Record comorbidities that may interfere with wound healing.
  • •Advise against smoking or use of nicotine products.

Physical Examination

• •Look for an obvious (open) or more subtle (closed) injury in which the patient has pain/swelling and hematoma under an intact and adherent nail plate.
• •If injury involves more than the nail bed, assess for tissue viability and loss of sensation.
  • •The finger should be examined prior to injecting a local block to obtain an accurate neurovascular exam
• •May or may not involve the bone (radiograph necessary)

Treatment

Closed Nail Bed Injuries

• •Can treat symptomatically or can remove nail plate and repair nail bed
• •Regardless of subungual hematoma size and/or fracture, trephination leads to similar cosmetic and functional outcomes with low infection rates and decreased health costs
• •Pressure from hematoma under nail plate often very painful
  • •Trephination (creation of hematoma drainage hole) with an electrocautery device or a large-bore needle may alleviate discomfort.
    • •Heat dissipated by underlying blood
    • •18-Gauge large-bore needle spun like a drill tip until it has gone through the nail plate

Open Nail Bed Injuries

• •Nail partially or completely avulsed from nail bed
• •If underlying fracture, treat as open fracture with irrigation/débridement and antibiotics (though can be done in emergency room).
• •Usually repair of soft tissue is enough to align bone fragments.
• •A displaced distal shaft fracture may require pinning (with Kirschner wire or percutaneously placed 20-gauge needle “drilled” across tip of finger by hand).
• •Injuries are often intimidating, but after hemostasis is obtained and adequate irrigation performed, the “pieces” will often come together.
• •Steps to repair
  • •Digital block
  • •Copious irrigation with saline
  • •Prep and drape hand (sterile procedure)
  • •Tourniquet control is obtained with a finger Tournicot or a sterile Penrose drain wrapped around the base of the finger.
  • •Remove any partially avulsed or remaining nail plate with a hemostat or by separating its connection with the nail bed using a Freer elevator (be careful not to avulse more of the nail bed).
  • •Repair the skin surrounding the nail bed with 5-0 nylon sutures first.
  • •Repair the nailbed:
    • •Meticulously reapproximate the wound edges of the nail bed with a 6-0 tapered chromic suture under loupe magnification.
    • •Alternatively, use Histoacryl Blue (monomeric n-butyl-2-cyanoacrylate) or octylcyanoacrylate (Dermabond). Octylcyanoacrylate has superior tensile strength.
      • •No differences in cosmetic and functional outcomes exist at 1 year after treatment with suture repair and octylcyanoacrylate tissue adhesive.
      • •Using octylcyanoacrylate tissue adhesive heals nailbed wounds significantly faster than suture repair.
  • •Place a new “nail plate” to act as a spacer under the nail fold and to splint the nail bed.
    • •If the nail plate is mostly intact, it can be cleaned and replaced.
      • •Prior to replacing the native nail, create several holes to allow for drainage to prevent infection
    • •Other options include:
      • •Silicone sheet
      • •A piece of the foil packaging from the suture
      • •Dry Nu Gauze or Xeroform with the petroleum scraped off (this will absorb some of the blood, dry out, and harden into a protective “nail plate”)
  • •The nail/foil/silicone sheet is held in place with a 5-0 nylon suture that should be removed in 2 weeks.
    • •Simple sutures from spacer to eponychium and paronychia
• • The wound is dressed with nonadherent gauze (Xeroform or Adaptec) followed by a 2 × 2 gauze patch and a protective aluminum splint held in place with Coban.
• •Any injury that involves the germinal matrix (extends proximal to the eponychial fold) will require appropriate exposure of the injured area. The eponychial fold must be incised (45 degrees angle to long axis at the proximal corners) and raised as a proximally based flap. The incisions can be repaired with simple interrupted 5-0 nylon.
• •Treatment of more extensive injury may require referral to a hand specialist.
• •In cases of severe crush injury or partial tip amputation with an avulsed nail bed, the nail bed may be protected with a nail plate to allow spontaneous regeneration or reconstructed with:
  • •Full- or split-thickness nail bed graft
  • •Integra secured with octylcyanoacrylate
  • •split thickness skin graft if entire nail bed is avulsed
  • •reverse cross finger flap
• •Loss of more than 50% of supporting bone (partial amputation) is an indication for nail ablation, which requires the excision of the germinal matrix.

Prognosis

• •The final functional and cosmetic outcome depends on the amount of nail bed that remains intact, the severity of the injury, and the patient’s comorbidities.
• •The patient may, on average, expect full nail growth in approximately 2 to 5 months. There is normally a lag in nail growth after this type of injury. The new nail may have temporary divots, a “hump,” or stripes that will usually improve with time.

Complications

• •If scar is present due to inappropriate alignment of lacerated edges, nail deformities are likely to occur.
• •If the eponychium is damaged, the nail may look dull.
• •Eponychium fusing with germinal matrix can lead to fissured nail and tender scar.
• •Scarring of the germinal matrix can lead to split nail or absence of the nail.
• •Sterile matrix damage can lead to nonadherence (onycholysis) of the nail.
• •Bone spur or uneven nail bed can lead to nail ridge.
• •If the lateral skin groove is not maintained it can lead to ingrown nails.

Considerations in Special Populations

• •Pediatric nail bed injuries typically require the involvement of a hand surgeon.
  • •More likely to need conscious sedation or a trip to the operating room for repair.
  • •Consider a more restrictive dressing (such as a cast) to prevent disruption or contamination of the repair.
  • •Seymour fractures—suspected with proximal nail avulsion or widening of physis. Nail must be removed with adequate irrigation and debridement, splinting, or possible pinning for reduction and stability.
• •Acrylic nails/ultraviolet (UV) gel nail polish
  • •Harbor pathogens.
  • •Mask nail bed injury.
  • •If pain/swelling over the fingertip with concerning mechanism treat with high suspicion. Remove acrylic nail/gel nail polish to adequately assess the fingertip.

Patient Instructions

• •Hand elevation to decrease swelling and pain
• •Leave the dressing intact until return appointment to minimize disruption to the repair.
• •Avoid getting the repaired site dirty or wet; avoid using the injured extremity until cleared to do so by the physician.

Seek Additional Information

• Brown R, Zook E, Russell R: Fingertip reconstruction with flaps and nail bed grafts. J Hand Surg Am 1999; 24A: pp. 345-351.
• Dean B, Becker G, Little C: The management of the acute traumatic subungual haematoma: a systematic review. Hand Surg 2012; 17: pp. 151-154.
• Meek S, White M: Subungual hematomas: is simple trephining enough? J Accid Emerg Med 1998; l5: pp. 269-271.
• Richards A, Crick A, Cole R: A novel method of securing the nail following nail bed repair. Plast Reconstr Surg 1999; 103: pp. 1983-1985.
• Roser S, Gellman H: Comparison of nail bed repair versus nail trephination for subungual hematomas in children. J Hand Surg Am 1999; 24A: pp. 1166-1170.