Mallet finger

Mallet finger

Mitsutoshi Hayashi

Mitsutoshi Hayashi

Doctor of Medicine, specialist in the Japanese Society of Rehabilitation Medicine, specialist in the Japanese Society of Orthopaedic Surgery, specialist in the Japanese Society of Rheumatology, staff to strengthen JOC, and sports physician certified by the Japan Sports Association

Mallet finger

Mallet finger often occurs when a ball hits fingertips in the extension position, and a stress in the flexion direction is applied to the DIP (distal interphalangeal) joint. Therefore, baseball, softball, volleyball, and other ball sports are common sports in which the injury occurs.

Disease Overview

A deformity in which the DIP joint of the finger (typically the first joint) cannot be extended completely is called mallet finger. The extensor tendon attached to distal phalange may rupture, occasionally accompanied by avulsion fracture, deformity of the finger (mallet deformity) or limitation of range of motion when a ball hits the fingertips (mainly on the nail side) in the extension position, and a stress in the flexion direction is applied to the DIP joint.

Cause and mechanism of onset

Cause of the injury

It is most common in ball sports, such as baseball (often in catchers), softball, basketball (when passing), volleyball (in overhand passing or blocks), and handball. The ball bounded on the floor or ground hits the fingertip directly may cause the injury by adding a stress on the DIP joint. It occurs in a wide range of the sports levels from top to recreation.

Mallet finger

Figure: DIP joint with stress in the flexion direction may be accompanied by a rupture of the extensor tendon.

Marett's finger 1

Photo 1: Mallet finger causes typical flexion deformity.

Marett's finger 2

Photo 2: Mallet finger accompanied by avulsion fracture of the DIP joint


The main symptoms are aching pain, swelling, reddening, and a feeling of warmth at the DIP joint of the finger, and mild tenderness and typical deformity (Photo 1) may occur with avulsion fractures. Make sure to seek medical attention in such cases.
Because symptoms of sprains and ligament injuries are similar to those of avulsion fractures, the differential diagnosis is difficult and requires an X-ray check (Photo 2).

Treatment and rehabilitation


The DIP joint of the finger is hyperextended with a splint and fixed for 6 weeks. Large pieces of avulsed bone are treated surgically with reduction and fixation (Photo 3).

Marett's finger 3

Photo 3: An example of surgical fixation of avulsion fracture.


Without adequate period of immobilization, the mallet deformity may persist or recur, making full extension of the fingertip impossible.


The first period: Acute stage (immediately after to 3 weeks after the injury)

First aid should be RICE therapy. In some cases, a cast or splint fixation is used to control pain and swelling. Gentle rehabilitation of the upper extremity, such as a movement of wiping the desk with a towel during fixation, can be done. Lower extremity exercises are permitted soon after the injury.

The second period: Range of motion training (3 to 6 weeks after the injury)

The fixation may be removed after the local rest period ends. Training to expand the range of motion of the finger joints (DIP joint; Proximal interphalangeal (PIP), the second joint; and metacarpophalangeal joint (MP) joint, the third joint) by autokinetic and passive movements, such as lightly grasping clay and pulling a towel, may be then performed gradually.

The third period: Increasing muscle strength (4 to 8 weeks after the injury)

Strengthening (afferent) muscles with a rubber ball may be proactively performed. Change the joints to place the burden by holding a ball with bending or stretching the fingers. Just like tube exercises, use rubber bands to make a stress directly applied to the injured finger and strengthen (afferent and efferent) the muscles. Also, dorsiflexion and palmar flexion of the wrist joint may be performed to strengthen joint movement around the wrist.

The fourth period: Return to sports (8 to 12 weeks after the injury)

Restart passing practice gradually. Training, such as thumb push-ups, may be performed without impact but with strong stress on the fingers. To return to sports, athletic tape may be used proactively to prevent recurrence and to help patients feel psychologically secured.

Extra edition: It’s just a sprained finger, but it’s still a big deal.

The sprained finger is a generic term generally representing finger injuries. It includes a variety of conditions, ranging from mild injuries such as bruises and sprains to ligamentous injuries and to avulsion fractures and dislocations. Therefore, treatment may take 2 to 3 days or several months. It is recommended to seek medical attention in the following cases: swelling, severe pain (sausage-like swelling), deformed, internal bleeding, weakness, inability of gripping, and slow healing. Finger disorders tend to be neglected in sports settings, but caution should be exercised because they may simply be viewed as sprained fingers and may preclude appropriate initial measure (treatment) or are required to return too early before complete healing. Regarding the way to distinguish the symptoms, if the finger joint do not fluctuate (loose), it would be the sprain. In case of ligament injuries, the instability on the finger joints may be found because the ligaments, which are the stoppers of the joints, are stretched. It requires a treatment period of 2 to 3 weeks for sprains, 2 to 3 months for ligament injuries, 2 to 3 months for fractures, and 1 to 2 months for dislocations. The sprained finger is very serious injury.

Yoshizumi Iwasaki

Yoshizumi Iwasaki

NATA certified athletic trainers, certified athletic trainers from the Japan Physical Education Association, and chairman of the Japan Core Conditioning Association (JCCA)

Trainer’s Edition


Prevention of finger injuries is the most important. Conditioning with awareness of injury prevention is often used as a synonym for increased fitness, such as weight training, reinforcement exercises, and running and stepping sports. However, prevention needs to be attained with coordination and balancing exercise. The same goes for finger conditioning, simple reinforcement of the extensor tendon or flexor tendon may cause injury if the rhythm or timing to use muscles are not matched. The first step in prevention is to master the timing to put muscle while acquiring the appropriate athletic skills. In particular, the finger may be injured as the patient is not able to use the muscle at wrong timing when blocking, so he/she has to practice to move the body in coordination with eyes so he/she can always perceive the timing of contact with the ball.

On-site evaluation and first aid

In the event of a mallet finger or Bennet finger, there is a prominent deformity that requires immediate referral and transfer to hospital. It is difficult to diagnose dislocations, fractures, and tendon ruptures unless a doctor sees the injury. Some coaches may take the patient with an open dislocation or fracture to the hospital, but otherwise they try to reduce the deformity on site. In case of a rupture of tendon or fracture, these kinds of approaches should be contraindicated and avoided as those may lead to serious injury. At medical institutions, discussions on whether to use conservative treatment or surgery are repeatedly continued, but the players tend to continue to play while deformity remains.


Conditioning in the field needs to be linked to rehabilitation in the hospital. Once the patient has returned to the sports field after complete rehabilitation in the hospital for range of motion and muscle strength, the training should be continued at the field with the aim of being even stronger and more flexible, so that strong external forces cannot make the finger broken again. This conditioning must gradually bring it closer to the actual movement and lead to practice and game. This section introduces examples of a combination of extension exercises with rubber, flexion exercises with squeeze balls and the combination of both exercises. These types of exercises are performed alone, but make sure to try to imitate actual sports movements as much as possible. For example, they can be incorporated into the throwing motion to extend when taking back and grasp the ball when following through.

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