Introduction 

Injuries to any area of the body have an impact on our daily lives, and hands and fingers are especially significant for athletes. Sports injuries are quite prevalent, with fingertip injuries being particularly common.  Our hands, wrists, forearms, and arms are made up of bones, muscles, tendons, and ligaments. Any harm to any of the structures might cause long-term consequences.
Sometimes, even minor-looking injuries, if left untreated, may cause lifelong deformity in the hand and finger.
There are different types of finger tip injuries, and each of the injuries affects either the tendon, bone, muscle, or ligament. This article will provide a detailed discussion of  mallet finger and other distal finger injuries

Basic anatomy of the finger

Before diving deep into the distal finger tip injuries, let us review the fundamental anatomy of the hand. The human hand consists of 27 bones, of which:

• Eight bones are present in the wrist, called carpals
• Five bones in the palm(metacarpals)
• Fourteen bones in the finger(phalanges)

This picture illustrates many types of bones constituting the hand and wrist. Let us now elucidate the relationship between muscle and bone.  Tendons link muscles to the bones and facilitate the movement of the hand.¹ 

The two primary types of tendons that regulate finger movement include:

• The extensor tendons run along the back of the finger and help in the extension or straightening of the hand
• The flexor tendons run along the palm side and help in bending the fingers and thumb^3,4

The distal interphalangeal joint (DIP), involved in mallet finger, is stabilised by the extensor tendon on top and collateral ligaments on the sides.¹ When the extensor tendon either breaks or gets detached, the fingertip droops, as shown in mallet finger injuries.¹,⁶

Understanding this anatomy is crucial to identifying which structure—bone, tendon, or joint—is involved in different fingertip injuries.

What is mallet finger? 

Mallet finger, also called “baseball finger,” is an injury that affects the tip of the finger. It happens when the tendon that straightens the last finger joint (called the distal interphalangeal or DIP joint) breaks off or is torn away from the bone. This usually happens when something hits the fingertip hard, like any type of ball or a sudden hit, causing the tip to bend suddenly and forcefully. After the injury, the fingertip bends down, and you can’t extend it on your own.¹

Unlike other injuries, a mallet finger doesn’t always hurt much immediately, but the inability to lift the fingertip is the main sign. There may also be swelling or bruising at the joint.²

Mallet finger is a common sports injury, but it can also happen during daily tasks like making a bed or tucking in a shirt, or wherever we are bending our finger forcefully. If left untreated, it can lead to a permanent deformity called a swan-neck deformity, where the finger looks bent in an unusual shape.³

Treatment usually involves wearing a splint that holds the fingertip straight for several weeks, allowing the tendon to heal on its own.⁴ In rare cases with bone fractures or joint misalignment, surgery may be needed.⁵,⁷

Common injuries that mimic or overlap with mallet finger 

This diagram depicts the main structure of the finger, which is usually affected in finger tip injuries. Let's discuss now a few distal finger injuries that are fairly comparable to mallet finger.

Jersey finger 

As the name suggests, jersey finger mostly happens while grabbing another player’s jersey, when the finger is suddenly pulled back. The main characteristic of the affected finger is that we can’t bend our finger tip, opposite to the thumb, index finger, and the middle finger are most commonly affected

Jersey finger is caused by a break of the flexor tendon, which otherwise helps our finger to straighten. In the jersey finger, the finger remains straight even if we try to bend it. Its treatment usually requires surgery to repair the broken tendon. The treatment shoprompe, patient can have a favourable prognosis.⁹,⁵  

Tuft fracture 

A tuft fracture is the breakage in the distal phalanx part of the ger bonewhich is actually the finger tip bone. It is usually caused by the fall of a heavy object on the finger or by a door. It is followed by pain, swelling and bruises. Unlike mallet finger, it does not affect any tendon; therefore, there is no restriction in the movement of the finger in most cases. Its treatment involves splinting and pain relief, but if there is nail bed injury, special care must be taken.²,⁹  

Distal interphalangeal joint (DIP) dislocation 

Displacement of the distal interphalangeal joint from its position causes DIP joint dislocation. This can happen due to any sudden injury to the finger. It also causes pain, swelling and a bent finger tip. There is no tendon breakage in this case; the last joint of the finger tip (DIP) joint has shifted from its original space. This can be fixed by putting the joint back in its position, followed by splinting.¹⁰,¹²

Subungual hematoma & nail bed injury

Subungual hematoma and nail bed injuries are very commonly seen in our daily lives. If our finger comes under a very heavy object or comes inside the hinge of the door, we have seen a blood clot under the nail bed. This is called a subungual hematoma

It is usually characterised by throbbing pain, swelling and dark red to purple discolouration under the nail bed. In case of severe injury complete nail bed may get damaged. Unlike mallet finger, a subungual hematoma does not affect the movement of the finger, as there is no breakage in the tendon. Proper treatment is required if pain and pressure become high.²,¹³

Boutonniere deformity 

Injury in the middle joint of the finger, also called as proximal interphalangeal phalanx joint (PIP), causes boutonniere deformity. Mallet finger occurs due to injury in the DIP joint and causes the permanent bending of the finger. In this case middle joint bends downwards and the tip of the finger backwards. It happens when the finger is forcefully hit, and a buttonhole appearance is seen in the finger. Its treatment involves splinting, where the finger is placed at its accurate position, and with the help of the splint, it is stabilised. In a few cases, surgery may also be required.^11,12 

Comparison table 

Summary 

This article discusses various distal finger tip injuries along with mallet finger. Mallet finger is a finger tip injury characterised by a bent finger and is caused by the breakage of the extensor tendon present at the outer surface of the hand. It can sometimes be confused with other finger tip injuries. In this article, we have discussed various other injuries like: jersey finger, which is totally opposite to mallet finger— the finger is straightened, and we cannot bend it. Other finger tip injuries like boutonniere deformity, tuft fracture, subungual hematoma and nailbed injuries have been discussed. Most of the injuries happen due to a sudden hit or the dropping of a heavy object on the finger. Treatment for almost all the injuries includes splinting, pain relief and in some cases surgery.

Frequently asked questions

Can I leave a mallet finger untreated?

No, leaving a mallet finger untreated may cause a permanent deformity, so it is better to get it treated.

Can I fix it at home?

Treating mallet finger at home is a little challenging, as it needs a special splint that is attached to the finger so that it is in a stable position. So getting it treated by a doctor is a better option, as there is difficulty in maintaining a stable, straight position of the finger without a customised splint.

What if my child has a finger droop after sports?

If your child has a finger droop after sports, there is a possibility of mallet finger. A doctor’s visit is very important to identify the problem and to rectify it. 

How long can splinting heal the finger?

The splint is usually worn full-time for 6 to 8 weeks, and sometimes part-time for a few more weeks afterwards. It's very important not to bend the fingertip during this time, or healing can be delayed.

Will I need surgery?

No, normally, mallet finger does not need surgery. But in a few rare cases, there is a requirement for surgery if not treated by non-surgical options.