Mallet Finger Clinical Presentation

Updated: Mar 09, 2022
  • Author: Roy A Meals, MD; Chief Editor: Harris Gellman, MD  more...
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In mallet finger, the patient’s history involves a forced distal interphalangeal (DIP) joint flexion injury, after which he or she notices an inability to actively extend the distal joint (though full passive extension remains intact). The dorsum of the joint may be slightly tender and swollen, but often the injury is painless or nearly painless. Patients may think that the joint is only sprained and continue playing sports, with 1 or more days passing before they notice a loss of active extension.

Typically, the athlete with a mallet fracture has a history of a direct blow to the finger, followed by pain and swelling at the DIP joint and an inability to actively fully extend the joint.


Physical Examination

The physical examination findings of mallet finger include localized swelling and tenderness to palpation at the affected DIP joint, as well as an inability to actively extend the injured joint. (See the images below.)

Despite active extension effort, the distal interp Despite active extension effort, the distal interphalangeal joint of the index finger rests in flexion, characteristic of a mallet finger.
Typical mallet finger deformity. Typical mallet finger deformity.

In some individuals, the swan-neck deformity, with hyperextension of the proximal interphalangeal (PIP) joint, may be found, owing to imbalance of the extensor mechanism. However, this is more often a late finding in untreated injuries.

Mallet finger injuries have often been described in terms of Doyle's classification, which comprises the following four main types [1] :

  • Type I - Closed injury with or without small avulsion fracture
  • Type II - Open injury; laceration
  • Type III - Open injury; abrasions with loss of skin or tendon
  • Type IV - (A) Physeal injury to distal phalanx (children); (B) fracture fragment involving 20-50% of the articular surface; (C) fracture fragment involving more than 50% of the articular surface