1. Mallet finger is an injury to the extensor mechanism of the finger.
Mallet finger occurs when the distal portion of the extensor tendon is disrupted. When this happens, the fingertip droops down and cannot be held straight against gravity.
2. It usually happens as a result of a jammed finger.
Typically, the mechanism of injury is a forced flexion of the distal interphalangeal (DIP) joint. This is the knuckle closest to your fingernail. When the finger is being held straight by the pull of the extensor tendon, and then something forces the fingertip down, it can rip the tendon off the bone. When that happens, there is nothing left to straighten the fingertip and it droops. This usually happens when a ball strikes the tip of the finger, such as in baseball. Other common sports are basketball and volleyball. The most frequently involved fingers are the long, ring and small fingers. Most times, it is the dominant hand that is involved, because that is the one that people use to reach.
3. The bone may fracture instead of the tendon ripping.
Sometimes, instead of the tendon tearing, the tendon pulls off a piece of bone off of the distal phalanx (bone under the fingernail). The size of the bone is variable. It may be very small, or it may involve a significant portion of the joint. Sometimes, the joint is actually subluxed (partially dislocated) if the fragment is large enough. This is usually termed a bony mallet finger. The size of the bone fragment dictates treatment.
4. Most mallet fingers are treated with an extension splint.
A splint keeps the fingertip straight, allowing the tendon to heal back to the bone. The splint can be made of plastic, custom thermoplastic or aluminum foam. Whichever splint you choose, the splint should be on full-time (except for cleaning) for six to eight weeks. The splint may be removed for cleaning, but the finger should be straight while it is done. Usually that involves placing it on the counter-top while you wash it. If the finger bends, the clock starts over, because that means the tendon fibers have ripped apart again. After the first six to eight weeks, the splint is usually worn at nighttime for another few weeks. One thing to watch out for is the skin above the DIP joint. Sometimes the splint places so much pressure on that area that the skin is compromised, which can lead to infections.
5. Surgery is necessary when the bones don't line up.
If the bone fragment involves over one-third of the joint, or the joint is subluxed, surgical pinning is the better option. This keeps the joint reduced in place, which prevents future stiffness. The pins stay in for four to six weeks.
