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Nail Injuries

Nail Injuries Overview

The fingernail is an important part of fingertip function. It provides support for the finger pad and improves sensation. The toenail functions in a similar manner in the foot.

Injuries to the nail can range from a bruise under the nail to separation of the nail from the nail bed. They can be complex wounds to repair. Permanent deformity to the nail can result, even after proper repair.

The nail is a complex structure involving 3 different layers.

The nail bed (or matrix or plate) is underneath the nail and is responsible for nail growth and support.
The nail itself is the hard substance on the back of the finger or toe.
The eponychium (cuticle) and lateral nail folds (raised skin on the sides of the nail) are also part of the nail.

Nail Injuries Causes

Most injuries to the nail are from 1 of 3 mechanisms.

Crushing forces such as hammers, doors slamming on fingers, human bites, or machinery
Slicing or cutting such as knives, box cutters, or machinery
Tearing or ripping such as stubbing a toe or catching a fingernail on an object

Nail Injuries Symptoms

There are 5 categories of injury that can occur to the nail. Often, a combination of these injuries occurs in the same nail.

A subungual hematoma (nail bruise) is a collection of blood under the nail. It is usually a red or purple color, which fades to blue over a few weeks. The entire finger or toe throbs with every heartbeat and is painful to touch or even move through the air. A nail bruise can be found by itself, or it can be seen in combination with other nail injuries.
A nail laceration can refer to a cut through the nail, to the nail bed, to the cuticle or lateral nail folds, or any combination of these. There is always blood visible on the skin. The nail can appear quite mangled depending on the type of injury.
A fingertip amputation means that a portion of the fingertip, including part or all of the nail, has been removed from the rest of the finger. Bone may or may not be visible.
A nail avulsion occurs when a portion of the nail is lifted off the nail bed or is sticking out of the skin at the base of the nail (the cuticle). There is usually blood visible. This is often associated with a laceration.
A fracture of the bone under the nail can also be associated with injuries to the nail, particularly with crushing injuries. This is called a distal tuft fracture. Unless there is an obvious bend (deformity) in the end of the finger, an x-ray will be needed to make this diagnosis.