- Caused by forceful flexion to the end of an extended finger
- Most frequently occurs in contact or ball-handling sports such as baseball, football and basketball
- The terminal extensor tendon on the dorsum of the finger at the DIP is torn, stretched or avulsed
- Pain, swelling (+ / – bruising) on the dorsum of the DIP joint
- Flexed posture of finger tip due to inability to actively extent it
- Passive (by the examiner) extension is usually possible. Inability to extend DIP passively indicates bony or soft tissue entrapment
- The degree of DIP angulation often reflects the severity of the tendon disruption
- Open injuries are rare
Shows a middle finger with Mallet deformity
- X-Ray of finger
- Look for a dorsal avulsion fracture of the distal phalanx at DIP joint
Mallet Finger X-Ray
Open injury, inability to passively extend DIP joint or large fracture > 30% of joint surface:
- Call plastics registrar for review and fast the child for possible urgent surgery
All other closed injuries:
- Preferred splint – Stax splint (see below)
- Alternative splint – Zimmer splint (see below )
- use this if unable to find a suitable size Stax splint or Stax splint is unavailable
- Both splints are designed to splint the DIP joint but permit PIP joint movement
- Instruct the patient / family to not remove the splint, as even brief DIP joint flexion can delay healing and impair final joint function
STAX FINGER SPLINT
Dorsal part of Stax splint. Note that it has a number to indicate size of splint.
Volar aspect of Stax finger splint
Fix it to the finger just distal to PIP joint with a small adhesive strip (e.g. elastoplast)
Close up of the volar aspect of the Stax splint
KLEINERT MODIFIED DORSAL FINGER SPLINT (Mexican Hat Splint)
Zimmer splint (aluminium with foam backed splint) is cut to the appropriate length, from the finger tip to just distal to the PIP joint.
Use sharp scissors to remove the middle one-third of the foam padding. Bend each end of the splint to form a slight concave contour.
The patient is instructed to hold the injured finger in hyperextension.
The splint is then affixed to the dorsum of the digit by two separate tapings.
Close-up look at the completed splint.
PMH ED Guideline: Mallet Finger – Last Updated November 2014
- Rebecca Bassett et al. Extensor tendon injury of the distal interphalangeal joint (mallet finger). Up To Date.
- R. G. Hart et al, The Kleinert modified dorsal splint for Mallet finger fracture. American Journal of Emergency Medicine 2005 (23), 145‐148.
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