Mallet finger is caused by a forceful blow or impact that bends the tip of your finger down while it’s extended, tearing or stretching the tendon that straightens it. The most familiar scenario is a ball striking an outstretched fingertip, but the injury also happens during surprisingly ordinary tasks like tucking in bedsheets, pulling up socks, or catching your finger in a door.
How the Injury Happens
The tendon that runs along the top of your finger and straightens the last joint is called the terminal extensor tendon. It attaches to the bone at the very tip of your finger. When something forces that fingertip to bend sharply while the tendon is pulled tight, the tendon can stretch beyond its limit, partially tear, or rupture completely. The result is a fingertip that droops and can’t straighten on its own.
In more severe cases, the force doesn’t just damage the tendon. It pulls a small chip of bone away from where the tendon attaches, creating what’s known as a bony mallet or mallet fracture. Less commonly, a deep cut across the back of the finger can sever the tendon directly, or a forceful hyperextension (bending the finger backward) can fracture the bone at the base of the fingertip.
Sports Injuries and Everyday Accidents
Sports involving balls are the classic culprit. Basketball, baseball, football, volleyball, and cricket all put fingers in the path of fast-moving objects. Baseball players often describe the injury as a “jammed finger” after a ball hits an outstretched hand. But any sport where your fingers absorb direct impact carries risk.
What surprises many people is how little force it sometimes takes. Common household mechanisms include pulling up socks or stockings, tucking sheets into a mattress, pushing a shirt into your waistband, or getting a finger caught in a closing door. These low-energy events are especially likely to injure the tendon in older adults, where the tissue may already be weakened by wear or mild arthritis. Over time, chronic inflammation in the finger joint can gradually degrade the tendon until even a minor stress causes it to give way.
Who Is Most at Risk
Mallet finger is most common in young and middle-aged men. The average age at injury is 34 for males and 41 for females. Athletes who play ball sports are at higher risk simply because of repeated exposure, but the injury is far from exclusive to sports. People in occupations that involve manual handling, and older adults whose tendons have lost elasticity, are also frequently affected.
There may even be a genetic component. One study tracked 24 members of a single family across three generations and found a pattern suggesting a familial predisposition to the injury, likely related to inherited differences in tendon strength or structure.
Tendon Tear vs. Bone Fracture
There are two distinct versions of mallet finger, and they behave differently. The distinction matters because it affects how the injury is treated and how long recovery takes.
- Tendinous mallet finger involves a tear or stretch of the tendon itself, with no broken bone. It tends to occur in older patients after low-energy injuries and is often surprisingly painless. The middle and ring fingers are most frequently affected. The fingertip typically droops more noticeably, with an average droop of about 28 degrees.
- Bony mallet finger involves a fracture where a fragment of bone gets pulled away along with the tendon. These tend to happen in younger patients (average age around 40) from higher-energy impacts, and they’re always painful. The ring and little fingers are the most common sites, and the droop is usually less severe, around 15 degrees, because some bony connection remains intact.
An X-ray of the finger is the standard way to tell the two apart. The lateral view shows whether a bone fragment has been pulled away and whether the joint has shifted out of alignment.
What It Looks and Feels Like
The hallmark sign is a fingertip that hangs down at an angle and won’t straighten when you try. You can push it straight with your other hand, but the injured finger can’t do it on its own. This gap between where the finger rests and where it should be is called an extension lag. Swelling and tenderness at the last finger joint are common, especially with bony injuries. With a pure tendon tear in an older adult, there may be little pain at all, which sometimes leads people to delay getting it checked.
What Happens if It Goes Untreated
Leaving a mallet finger untreated doesn’t just mean a permanently droopy fingertip. Over weeks to months, the imbalance in the tendon system can cascade up the finger. When the tendon at the tip is slack, the pull of the tendons shifts toward the middle joint of the finger, gradually forcing it into hyperextension while the tip stays bent. This creates a characteristic zigzag shape called a swan neck deformity. Once this develops, it becomes a much more complex problem to correct. The volar plate, a ligament on the palm side of the middle joint, stretches out, and the force imbalance across both joints becomes self-reinforcing.
How It’s Treated
The standard treatment for most mallet finger injuries is a small splint that holds the last finger joint straight, allowing the tendon or bone to heal in the correct position. The key is continuous wear. Removing the splint, even briefly, resets the healing clock because the tendon ends separate again the moment the fingertip bends.
Bony mallet injuries typically need about four weeks of continuous splinting, followed by four weeks of gradual weaning and gentle exercises. Tendinous injuries heal more slowly because tendons have a poorer blood supply than bone. They generally require six to eight weeks of uninterrupted splinting before the weaning phase begins. One important detail: bony mallet injuries should be splinted in a neutral or slightly bent position, not in hyperextension, because hyperextension was the mechanism that caused the fracture in the first place.
Surgery is generally reserved for cases where a large bone fragment is involved, the joint has shifted out of alignment, or splinting has failed. Most mallet fingers heal well without an operation, provided the splint is worn consistently and the follow-up exercise program is completed.