Facts on Nail Injuries
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 three different layers.
- The nail bed is underneath the nail plate and is responsible for nail growth and support.
- The nail plate 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 unit.
What Causes Nail Injuries?
Most injuries to the nail arise from one of three 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
What Are the Symptoms of a Nail Injury?
There are five 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 and is painful to touch or even move through the air. A nail bruise may occur 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.
Subungual Hematoma: Bleeding Under the Nail
- A subungual hematoma is a collection of blood in the space between the nail bed and fingernail
- Subungual hematomas result from a direct injury to the fingernail.
- The pressure generated by this collection of blood under the nail causes intense pain.
When Should I Call the Doctor About a Fingernail or Toenail Injury?
If the qualifications for home care are met (See "Self-Care at Home" below), then a visit to the doctor is indicated only in the following cases.
- It has been more than ten years since your last tetanus booster shot.
- Infection, redness, or drainage develops at the site of the injury two to seven days later.
- The injured person has diabetes, has poor circulation, AIDS, is on chemotherapy, or has another reason for poor healing or increased risk of infection.
Most nail injuries are best managed in a hospital's emergency department instead of at the doctor's office. You should be seen within six hours and can be transported by private vehicle. Calling an ambulance is unnecessary unless there are other more serious injuries. Anything worse than a small nail bruise should be brought to the emergency department for evaluation and repair. This includes the following examples.
- Any laceration (cut) or amputation of the nail, the nail bed, or the skin surrounding the nail
- Any part of the nail sticking out of the skin or pulled off the nail bed (nail avulsion)
- A nail bruise that takes up more than 25% of the total nail and that you would like to be drained
- Any bend or deformity in the fingertip indicating that the bone may be broken
- Any injury caused by a human bite or animal bite
How Is a Nail Injury Diagnosed?
The doctor will make a detailed examination of the hand or foot and the injured nail and decide the extent of treatment and repair necessary by performing the following procedures.
- The doctor will want to know exactly how the injury occurred to determine possible injuries and if the wound is contaminated (especially if it is from a bite).
- The doctor will ask about other medical problems, medications, allergies, and the date of your most recent tetanus shot.
- Your pulse and blood pressure will be checked.
- Possibly, an x-ray of the hand or foot will be taken.
- Blood tests are not usually required.
What Are the Home Remedies for Nail Injuries?
Home care should begin with initial wound care and evaluation of the injury.
- First, remove all jewelry from the affected hand or foot.
- Stop any bleeding by applying pressure with a clean cloth. When the bleeding has stopped, remove the cloth and examine the injury.
- Home care may be appropriate if there is only a subungual hematoma (nail bruise) that you do not want to be drained or that occupies less than 25% of the total nail if the finger or toe is not bent or deformed, and if there are no lacerations or avulsions of the nail. Do not be too concerned if there are some minor scrapes around the nail.
- Keep the hand or foot elevated above the level of the heart. This will help with the throbbing.
- Use acetaminophen (Tylenol) or ibuprofen (Advil) for pain if you are not allergic to these medications.
- Wash any cuts or scrapes in soap and water, then apply a bandage.
- If there are any lacerations, avulsions, a large nail bruise, or if the finger or toe is bent (deformed), you will need to go to a hospital's emergency department.
- Do not pull at the nail or try to remove it from the nail bed. Wrap any amputated parts in a moist clean paper towel, place in a zip-locked plastic bag, then place the bag in ice. Bring this with you to the hospital's emergency department.
- Wrap hand or foot in a clean towel.
- Check on whether your tetanus immunization is current.
What Is the Medical Treatment for Nail Injuries?
Basic wound care is the same for all nail injuries, although the specific repair techniques will vary depending on the type of injury. The wound will be cleaned so that the doctor can examine it more closely. A tetanus shot will be given if it has been longer than 10 years since your last one.
If a repair is needed, the finger or toe will be numbed up prior to starting work. This is usually done by injecting medicine at the bottom of the finger or toe. This makes the entire finger or toe numb, so that you do not feel the doctor working on the nail. Depending on the injury, the doctor may choose to inject the numbing medicine directly into the nail bed or nail folds instead of numbing the entire finger.
Sometimes a tourniquet to slow the blood flow is used on the finger or toe during the repair. This helps prevent bleeding during the procedure, so that the doctor can see the wound more clearly.
Antibiotics are usually not given unless the bone is broken and there is bleeding or a laceration, or if the wound is from a bite.
- Nail bruise: The doctor may decide to drain the blood by placing a hole in the nail plate. This painless procedure allows the blood to drain out of the hole and relieve the pressure and throbbing sensation. This can be done with a heated paperclip, a heated needle, or a battery-operated heating device. The doctor may occasionally choose to remove the nail and examine the nail bed for a laceration. This is more likely if it is a large bruise and the bone is broken.
- Nail laceration (cut): At least a portion of the nail will have to be removed prior to repair of the cut. The nail bed and the surrounding skin will have to be sewn up, often with several different types of sutures (stitches). After the nail bed has been repaired, the nail will be replaced and sewn or glued (with medical-grade glue) to the finger, or a special type of gauze will be inserted in place of the nail. This dressing will have to remain in place for two to three weeks.
- Fingertip amputation: The doctor will probably not be able to reattach the tip of the finger. If the piece is large and clean enough, a few major medical centers may try to reattach the tip or improve the final appearance of the finger using advanced techniques. Even with highly trained hand surgeons and microvascular techniques, there is a high rate of failure with this procedure.
- Nail avulsion: The nail sometimes can be replaced under the skin if there has been no damage to the nail bed. However, the nail bed has usually been injured and will have to be repaired.
- Broken bone: If the bone is still in line, the doctor will repair any other injuries. A splint will then be placed on the broken finger or the broken toe to keep the bone in place. If the bone is out of line, a bone or hand specialist may have to place a wire in the tip of the finger to keep the bone in place. Antibiotics may be given if there is a laceration involved.
What Is the Follow-up for Nail Injury?
- Any skin stitches or stitches in the nail will need to be removed in seven to 14 days. Any stitches in the nail bed will dissolve by themselves and can be left in place.
- The doctor may want to recheck the wound in three to five days.
- Take any antibiotics as directed.
- Keep the wound clean and dry. Follow any specific wound care instructions given by the doctor.
- Keep the hand or foot above the level of the heart to aid in pain control.
- If the doctor prescribed pain medicine, then take it as directed. Otherwise, acetaminophen or ibuprofen may be used for pain control if there are no allergies to these medications.
How Do You Prevent Nail Injuries?
Although most nail injuries are accidents, some precautions can be taken to reduce the chances of this happening.
- Keep nails trimmed short to keep them from snagging on objects.
- Always keep the supporting hand out of the potential path of a box cutter or other sharp object.
- Be careful around machinery or when using hammers.
- Use door guards to prevent children from accidentally closing doors on their fingers.
What Is the Prognosis for Nail Injuries?
Even with proper wound care, a permanent deformity of the nail is common. The nail will grow back, but it may have a groove or dent in it.
- If part of the fleshy part of the finger was lost, a hook nail may result. This occurs when the nail grows in a hook over the end of the finger or toe. This can sometimes be corrected later with plastic surgery.
- If the nail was removed, or if there is a large nail bruise, then the injured nail will probably fall off as a new nail grows back. It will take four to six months for a new fingernail to grow back, and 12 months for a new toenail.
- Infection can occur. This is more common with bite injuries or contaminated wounds. Infection is also a risk for people with diabetes or AIDS, those undergoing chemotherapy, those with poor circulation due to any reason, or those who have other problems that may decrease the ability to fight infection.
Nail Injury Picture
Anatomy of the fingernail. Top: the normal fingernail. Bottom: nail bed laceration with subungual hematoma. Click to view larger image.