Mallet Finger (Zones I and II)

Clinical presentation

Zone I and Zone II extensor tendon injuries may result in a mallet deformity, due to loss of continuity of the conjoined lateral bands at the DIP joint.

The history is usually a direct blow that forcibly flexes an extended finger. However, the trauma may also be minor, or even forgotten. If left untreated, apart from being painful, the digit becomes hooked and may eventually develop a swan-neck deformity due to compensatory hyperextension at the PIP joint.

Open injuries should be referred to a hand surgeon for primary repair.

Clinical management


Closed mallet finger injuries are usually treated conservatively.

Mallet finger deformity may be due to bone or soft-tissue injury and radiographs are needed to confirm this.

Referral criteria

Criteria for referral include:

  • The absence of full passive extension (indicating possible bony or soft-tissue entrapment requiring surgical intervention)
  • Joint subluxation or an avulsion fracture of more than one-third of the articular surface

There is evidence [16-17] to suggest that even the latter injury may be treated non-operatively with good patient satisfaction, although studies with longer follow-up are required to assess the effects of resultant DIPJ arthritis on treatment outcome.


Conservative treatment entails continuous splinting of the DIPJ in neutral or slight hyperextension for at least six weeks.

There is insufficient evidence [18, 19] to recommend any particular splint; all achieve similar outcomes, patient compliance being the key to a successful outcome.

Learning Bite

A well-fitting splint for a mallet finger is vital to ensure compliance and avoid skin breakdown, the main complication of conservative treatment. The PIPJ must be left free to allow mobilisation and prevent stiffness.