Mallet Finger Injury

“my finger doesn’t work”
“my finger is bent”
“my finger won’t straighten”
“my finger is drooped”

These are several of the most common things I hear when patients come in with a mallet finger. 

A mallet finger is the name for a ruptured (torn) tendon at the tip of the finger. A tendon rupture is where a tendon rips off the bone where it’s normally attached. 

This can happen by jamming the finger, by cutting the tendon on top of the finger, or even with a lot of pressure on the fingertip, like if you’re trying to rub paint out of the carpet. 

It usually happens in people over 40 years old. Sometimes these injuries hurt, but not too bad at all. That’s why lots of people come into my office several weeks after the injury. 

Some mallet fingers cause a huge droop – 45 degrees or more. Others are more subtle and minor; just a small droop. But in every case, the patient can’t extend (straighten) the end joint of the finger. 

The extensor tendon normally attaches to the dorsal (top) side of the finger. When your extensor muscle fires, it pulls the tendon, which pulls the bone up into extension.

Your flexor tendon attaches on the volar (bottom) side of the fingertip, and is about 6 times stronger than the extensor on top, so the finger rests in flexion (bent) without the extensor on top to hold it straight. 

The extensor tendon isn’t like a solid piece of rubber or plastic that just completely snaps in half every time. It’s made of millions of tiny strands of collagen, kind of like the strands of a rope or a mop. These strands can pull apart completely, partially, or on one side of the tendon or the other. 

Splinting

When the tendon tears off the bone, the bone at the end of the finger – the distal phalanx – droops down. If the tendon fibers are to heal, the torn ends need to be brought back closer together. In a mallet finger, we do this by splinting the end joint (DIP joint) straight. 

Splinting is the least risky, most effective treatment option for these injuries. The best splints are made by a hand therapist out of thin, moldable plastic. 

But even more important than the splint material is the fact that the splint MUST be worn full time. If you remove the splint and let the finger droop ONE TIME, all the healing is torn apart, and you have to start over. 

The therapist can teach you some tricks of wearing the splint, but it’s safer not to remove the splint for a full SIX WEEKS. 

Even when you do what you’re supposed to do and the splint is made perfectly, EVERY mallet finger injury heals with a slight droop. It may be three degrees or 10 degrees, but it won’t be completely normally straight at the end of the process. 

Even surgery doesn’t make this better. Even if I put a pin inside the finger to hold it straight, you’ll still have a droop. 

There are some surgeries that can be done for mallet fingers that stay VERY drooped after six or eight weeks, but none of them are very predictable, and all have more risk than the average carpal tunnel or routine hand surgery. 

Another reason the splint doesn’t work well is if the constant splinting is started late – a week or more after the injury. There’s just too much scar tissue formed between the ends of the tendon for it to heal correctly.