What is involved with nail bed injuries?
Injuries to the nail are often associated with damage to other structures that are in the same location. These include fractures of the bone (distal phalanx), and/or cuts of the nailbed, fingertip skin (pulp), tendons that straighten or bend the fingertip, and nerve endings.

What causes nail bed injuries?
Many result from crush injuries such as getting the fingertip caught in a door. Any type of pinching, crushing, or sharp cut to the fingertip may result in injury to the nail bed.

Presentation of nail bed injuries
Simple crushes of the fingertip may result in a very painful collection of blood (hematoma) under the nail. More severe injuries can result in cracking of the nail into pieces, or tearing off of pieces of the nail and/or fingertip, and possible injuries to the adjacent structures.

Diagnosis of nail bed injuries
An accurate history of the cause of the injury should be obtained. X-rays are recommended to look for associated fractures that may require treatment. Sometimes the full extent of the injury may not be evident until adequate anesthesia (usually local) is given and the nail is examined with magnification. Other medical conditions that may affect healing should be discussed with your physician.

Children's nail bed injuries  Children have different underlying bone anatomy. A growing child has a growth plate that may be fractured and the nail matrix can become entrapped in the fracture.   If a fracture is suspected care must be taken to avoid an unrecognized open injury of the growth plate.

Proper x-ray imaging is vital especially a good true lateral film.

Treatment of nail bed injuries
Restoring the normal anatomy of the nail and surrounding structures is one of the goals of treatment. However fracture treatment,  other soft tissue injuries, preexisiting arthritis or cosmetic elements  may make it impossible to predict the fate of the nail appearance. Sometimes simple hematomas are drained by making a small hole in the nail in order to relieve the pressure and provide pain relief. Draining a hematoma when there is a fracture below is not recommended. Straightforward cuts are repaired to put the parts back where they belong.

Repairing the nail bed to which the fragments of bone are attached usually restores alignment of many fractures of the fingertip. Larger fragments of bone may need to be pinned or require splinting to heal the fracture. Missing areas of nail bed can be grafted from the same finger or from other digits. Tendon injury may require splinting or pinning. Local flaps of skin may be used to replace missing skin, or the open area of skin may be allowed to just heal on its own, or covered with a skin graft. Suturing the nail directly to the eponychial fold should be discouraged

Prognosis
The final appearance and function of the nail and surrounding structures depends on the ability to restore the normal anatomy and the extent of the intitial injury. If the injury is sharp and can be repaired, a normal nail is  more likely. If there is more severe crushing of the nail bed, then there is a greater likelihood of nail bed scarring and subsequent deformity of the nail. If the germinal matrix (crescent-shaped zone at the base of the nail bed from which the nail grows) is injured, there will likely be a deformity of the nail as it grows. The function of the fingertip also depends on the extent of injury to structures other than the nail. It normally takes 3-6 months for the nail to grow from the cuticle to the tip of the finger. Often the first re-growth of the nail may be irregular and as the nail grows its appearance changes. Fractures that may be just below the nail bed may also affect the nails appearance despite a good effort to restore normal anatomy. Despite these prognostic statements no one can truly predict what the nail will look like a year later.

Surgical Reconstruction
Loss of part or all of the nail bed can be reconstructed with grafts from other digits. Grafts may be taken from the nail bed of a toe to prevent further injury or deformity of the fingers. The most common graft is a split-thickness graft to reconstruct missing nail bed. These type of procedures are  best discussed on an individual basis as often the extent of the injury precludes this type of reconstruction.

Figure 1: The anatomy of the nail bed and surrounding structures.

Figure 2: The anatomy of the nail bed and surrounding structures from a lateral view.

portions © 2006 American Society for Surgery of the Hand modified, adapted by www.handctr.com July 2009

Nailbed.pdf from ASSH (as it is unmodified  the content differs from this webpage)