The following are the most common findings when a nail is injured:

• Nail bruise is known as a subungual hematoma. After a crushing injury, blood collects under the nail plate causing a black-purple discoloration which fades to reddish-brown over weeks. The finger/toe may be painful and throb for a day or two. The discoloration will persist until the nail has grown out completely which for toes may take 12-18 months and for fingers may take 6 months.
• Nail laceration. This injury is caused by a cut through the nail and may affect the nail bed, cuticle, and even the rest of the finger or toe.
• Nail avulsion. This injury is caused by a tearing or ripping injury in which the nail or a portion of it is pulled away from the nail bed. This is often seen in association with a laceration.
• Finger or toe tip amputation. A portion of a digit along with the nail may be removed from the rest of the digit. Depending on the severity, the bone may be exposed.
• Fracture. The bone of the digit under the nail can be fractured or broken by a crushing injury. A subungual hematoma is often seen in association with this type of injury. An x-ray may be necessary to make the diagnosis.

Nails can be damaged in one of several ways:  A crushing blow such as with a hammer or car door, a cutting injury such as with a knife or other sharp object or a tearing injury such as when a nail is caught on an object or stubbed.

Anything more severe than a small nail bruise (affecting more than 25% of the nail) should be evaluated by a medical professional immediately following the injury.  The doctor will take a detailed medical history and examine the hand or foot where the injury occurred.  An x-ray may be necessary to evaluate for a fracture.

Basic wound care is the same for all injuries- stop bleeding by holding pressure, keep hand or foot elevated above the heart, wash any injuries with soap and water.

If a repair is needed, this will usually need to be done at an urgent treatment center or the emergency room. A tetanus shot may be needed if you have not had one in the past 10 years. If the injury is severe, a hand surgeon will likely be contacted to evaluate the injury.  If the injury is a nail bruise, the buildup of blood under the nail may need to be drained. This painless procedure will help relieve the pain and throbbing that is present.

Outcome and Management

If there was a large nail bruise, the nail will likely fall off as the new nail grows back. Sometimes, if the injury was severe enough to the area where the nail is made (under the cuticle), then a permanent nail deformity may occur. This may present as an indentation, groove, or splitting of the nail.

Infection can occur especially in cases of bite injuries or contaminated wounds or in patients who have compromised immune systems. If redness, swelling, or drainage develops at the site of the injury, it is important to have the area evaluated by a medical professional.