Nail pain is a common chief complaint in the emergency department. To understand the different injuries and how to repair them, it is important to have a good understanding of nail and fingertip anatomy.

Anatomy:

The eponychium: the cuticle

Nail bed: sterile matrix and germinal matrix which are both responsible for nail growth

Nail plate: the nail itself

The lunula: the junction of the germinal matrix (proximal) and sterile matrix (distal)

Common traumatic nail injuries:

Subungual hematoma

This is a hematoma that develops between the nail bed and the nail plate, it can be very painful due to increasing pressure. If the hematoma covers more than 50% of the nail bed, the nail plate should be trephinated to relieve the pressure. Trephination can occur using electrocautery, a nail drill, or an 18 gauge needle. Make sure to clean the nail prior.

Nail Bed laceration

A nail bed laceration should be suspected if the nail plate is damaged. This injury might require partial or full removal of the nail plate if there is an avulsion, disruption in the nail fold, or severe nail plate fracture. Nail bed lacerations can be repaired with a 6-0 absorbable suture or skin adhesive. If there is significant bleeding, a digital tourniquet formed from the finger of a glove can be used to create a bloodless field. Of note, nail plate removal is controversial and should only be done in the aforementioned circumstances.

Nail bed avulsion injuries: 

If the nail plate is avulsed with the nail bed, the nail bed should be removed from the nail plate and sutured back in place. The sterile matrix of the nail bed is more adherent to the nail plate so often avulsions occur more proximally (germinal matrix is loosely adherent) than distally. These injuries have the worst prognosis and often require consultation with a hand specialist. 

Distal phalanx fracture

About 50% of nail bed injuries have an association with a phalangeal tuft fracture. These fractures require repair of the laceration, replacement of the nail plate, and use of an aluminum splint. These fractures may also require hand specialist consultation. 

Fingertip amputations:

- Zone I: Nail and fingertip injuries distal to the distal phalanx. These injuries require cleaning, antibiotic ointment, petroleum jelly, a sterile dressing, and a splint. 

- Zone II and Zone III injuries require intervention by hand surgery.

Following an injury or avulsion, it is important to counsel patients that new nails take about 6-12 months to grow normally. After repairing the nail bed, the nail plate should be replaced and trephinated. The nail plate protects the sensitive portion of the nail and splints open the eponychium for new nail growth. If the original nail plate is severely damaged or unavailable, petroleum gauze can be used to maintain the eponychium. All wounds should be dressed with petroleum jelly and splinted so that the DIP joint is restricted for 7-10 days. Prophylactic antibiotics are usually withheld unless there are large amputations, avulsions, or fractures. 

Sources:

1.  Davenport M. Arm, Forearm, and Hand Lacerations. In: Tintinalli JE, Ma O, Yealy DM, Meckler GD, Stapczynski J, Cline DM, Thomas SH. eds. Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 9e New York, NY: McGraw-Hill; . http://accessemergencymedicine.mhmedical.com/content.aspx?bookid=2353&se.... Accessed May 30, 2020.

2.  Davenport D. Nail Bed Repair. In: Reichman EF. eds. Reichman's Emergency Medicine Procedures, 3e New York, NY: McGraw-Hill; . http://accessemergencymedicine.mhmedical.com/content.aspx?bookid=2498&se.... Accessed May 30, 2020.

3.  Blog.clinicalmonster.com. 2020. [online] Available at: <http://blog.clinicalmonster.com/2018/06/18/nail-bed-laceration-and-repair/> Accessed 30 May 2020.

4.  Morgan MA. Phalangeal tuft fracture: Radiology Case. Radiopaedia Blog RSS. https://radiopaedia.org/cases/phalangeal-tuft-fracture?lang=us. Accessed May 30, 2020.