Written by: Jon Andereck, MD, MBA (NUEM PGY-3) Edited by: Rachel Haney, MD, (NUEM Graduate 2017, US Fellow MGH) Expert review by: Danielle McCarthy, MD
Why Nails are Important
Nail injuries may have significant associated functional and cosmetic morbidity
Nail bed provides adherence and support for the nail
Nail Anatomy
Nail bed overlies the cortex of the distal phalanx and lies directly beneath the nail plate
Eponychium is the skin that covers the proximal end
Hyponychium is the skin edge at the distal nail margin
Cuticle is an outgrowth of the eponychium that provides a seal between the proximal nail fold and nail plate
Germinal matrix is the proximal portion of the nail bed responsible for nail formation and begins 7 to 8 mm under the eponychium; the distal end of the germinal matrix is the lunula
Subungual Hematoma
A simple subungual hematoma is not an indication to remove the nail; trephination is not indicated if the hematoma encompasses only 25%, there is no significant pain, or if injury was over 24 hours ago as the blood likely clotted and will not flow out.
Blood under the cuticle proximal to the nail is a clue that there is a deeper injury and usually the nail should be removed if there is significant pain.
There is controversy regarding treatment of subungual hematomas and whether simple trephination is enough or whether inspection of the nail bed for injury is required.
It was suggested that for subungual hematomas involving more than 50% of the nail bed, the nail should be removed given the risk of nail bed laceration. This was based on an initial study in 1987 that found that 16/27 patients with hematomas >50% had associated nail bed lacerations that required repair This study did not follow up with patients and did not have a control group so long term outcomes are unknown.
However, subsequent studies have shown that if there is no other significant finger tip injury, treatment by trephinating alone provides a similar good cosmetic and functional result.
If you don’t have a trephinator, what else can you use?
Heated paper clip
23-gauge 1-inch needle. Hold the needle over the hematoma, avoiding the lunula, twist and rotate the needle back and forth like a drill; no pressure needed.
Number 11 scalpel (slower, more painful, larger hole but better drainage)
Insulin syringe needle (29-gauge) can be used on toenails.
What if there is a fracture underneath?
Though there is a risk of turning the fracture into an open fracture, consider still performing the procedure if the injury is painful.
Can consider antibiotics if trephination is pursued, though there is no data.
It is always important to obtain an x-ray with any traumatic injury.
Nail Bed Repair
Suture the nail bed if a large subungual hematoma is associated with an unstable or avulsed nail
Good outcome depends on maintaining the space under the cuticle where the new nail will grow out from (the germinal matrix). If this area scars down, a new nail will not grow
If the nail is only partially avulsed or loose, especially at the base, lift the nail slightly to assess the nail bed.
If the nail is completely transected, it is best to remove the entire nail to suture the nail bed; in this case, suture the proximal and lateral nail folds first for better approximation prior to repairing the actual nail bed.
A sturdy needle (3-0 or 4-0) is needed to suture the nail back in place. Before replacing the nail and suturing it back in place, you can poke a hole through so the needle and suture can pass more easily.
A study in 2008 used dermabond for nail bed laceration repair showed similar follow up cosmetic and functional outcomes; using dermabond took about 1/3 of the time. It was a small study with only 40 patients and repair was done by orthopedic residents, but definitely a consideration
Some physicians will use dermabond to secure the nail in place as well
Key to success is achieving hemostasis and making sure you have a dry field before dermabond application
Another method to secure the nail in place is the figure 8 stitch proposed by hand surgeons
Protecting the exposed nail bed is essential, which can be done with the nail itself (wash well beforehand with normal saline), with the sterile aluminum foil from the suture pack, or with a piece of vaseline gauze. The nail should be reinserted under the eponychium to protect the open space for nail growth.
Consider a hand surgeon consult if the nail bed is extensively lacerated or if part of the nail bed is lost, as the patient my need a matrix graft.
Tell the patient to return for a wound check 3-5 days post repair. Replace any non-adherent material that was inserted into the proximal nail fold. Afterwards, the patient should perform dressing changes every 3-5 days.
Sutures that were used to reattach the nail should be removed in 2 weeks.
Nails grow at a rate of 0.1 mm/day and it takes approximately 6 months for a new nail to grow.
Instruct the patient to avoid any trauma or chemical irritants to the healing nail.
Tips:
Always use absorbable suture to repair the nail bed
Use a large suture and sturdy needle when suture the nail back in place; consider dermabond as an option
Use a finger tourniquet to maintain a bloodless field
Clean the nail bed prior to repair; clean the nail very well before replacement
Digital blocks are key
Repair the proximal and lateral nail folds first
If possible use the avulsed nail to protect the exposed nail bed and maintain the space for a new nail to grow
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