Mallet Finger

This Needs Splinting to Prevent Problems

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A mallet finger is an injury to the tendon at the tip of the finger that causes the finger to be permanently bent. You might injure your finger by jamming it. After the injury has occurred, you may notice that you are unable to fully straighten the tip of your finger. This may seem like a minor problem, but if it isn't splinted and corrected, you can have more problems in the future.

Causes of a Mallet Finger

A mallet finger is an injury to the extensor tendon on the back of the finger. The extensor tendon is the tendon used to straighten the finger. The tendon has several attachments on the back of the finger, including one just beyond the last knuckle that allows this last finger joint to extend (straighten). When the tendon is injured, there is nothing to pull that last knuckle straight, and therefore, the joint stays bent.

Some of the common causes of a mallet finger include:

  • Sports injuries were a ball strikes the end of the finger forcefully
  • Falls because you to land on your extended finger

People should be especially suspicious of injuries that occur resulting in the finger not looking normal, or not bending properly. If you cannot fully straighten the finger, or if there is a deformity of the finger, that is a reason to have a jammed finger injury evaluated by a trained medical provider.

Symptoms of a Mallet Finger

A mallet finger is an obvious injury, if you know what you're looking for: the last joint of the finger will be bent down, and while the joint can be straightened with assistance, you will be unable to fully straighten the tip of the finger on its own.

The pain associated with a mallet finger can be significant at the time of the injury, but is usually minimal within a short time. Most people with a mallet finger are tender at the site of the injury, just behind the base of the fingernail. Due to minimal pain, many mallet fingers go undiagnosed for weeks or longer, because people are unaware of the significance of their injury.

In some people, when the tip of the finger is struck quite forcefully, there may also be injury to the fingernail, and the underlying nail bed. Often there is bruising noted underneath the fingernail. Depending on the amount of blood that accumulates, this can lift up the fingernail, and in some situations the finger nail may fall off, although this is unusual.

X-rays are typically performed to assess the finger joints and the bones. Most mallet fingers cause damage only to the tendon, therefore the x-rays are interpreted as normal. There is also a condition called a bony mallet finger, where a small fragment of bone attached to the end of the tendon is also involved. If this fragment of bone is large enough, it may cause abnormalities in the alignment of the joint. This may lead to your doctor recommending surgical treatment.

Treatment of a Mallet Finger

Most often, a mallet finger can be treated with a simple splint. A Stack splint is the easiest type of splint to use for this injury. It is shaped like your fingertip and slips over your finger to below the level of the joint. You can find ones that are clear or are flesh-colored.

The difficult part is if the splint is removed and the finger tip is allowed to bend, the treatment must be restarted from the beginning. Since a Stack splint is usually worn for four to eight weeks, this can be a significant challenge! You will need to take care that you don't allow the finger to bend if you remove the splint to clean it, etc.

While the injury that causes a mallet finger is painful in the acute phase, within a few days, the swelling is typically settled down, and the painful symptoms have largely resolved. With a splint in place, and the fingertip not bending, there should not be significant discomfort. In fact, the lack of pain is often a problem, as people with this injury become less careful about proper treatment and splinting techniques. The pain is typically resolved long before the injury has fully healed.

There are some situations that may require additional treatment. Most mallet fingers are an injury to the tendon itself, but in some cases, the tendon may pull off a small fragment of bone from the finger bone. If the fragment is large enough, it may require surgical treatment to prevent joint problems from developing.

Surgical treatment may also be needed in situations where the injury is left untreated for more than four to six weeks. In these patients, a surgical correction of the tendon injury may be required. If a mallet finger is left untreated, the deformity of the finger can worsen. Patients who leave a mallet finger untreated may develop a deformity of the finger joints called a swan neck deformity.

A swan-neck deformity of the finger occurs following an untreated mallet finger injury. Because the tendon that straightens out the tip of the finger is pulled back, there is more force acting on the first knuckle of the finger. This abnormal force creates a hyperextension deformity of that knuckle leading to deformity over time. Sometimes a swan-neck deformity is a cosmetic issue, leading to no significant functional problems, other times a swan-neck deformity can impair the normal function of the fingers. For people with more severe deformities, surgery may be necessary to correct a swan-neck deformity.

A Word From Verywell

A mallet finger is more than just a typical jammed finger. When this injury occurs, the tendon that straightens out the tip of the finger is damaged. Without proper treatment, permanent deformity can be the result. Fortunately, most people can heal this injury with the proper use of a simple splint. Having this injury evaluated and properly treated is critical to the successful recovery from a mallet finger injury. Not having proper treatment can lead to permanent deformity of the finger.

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