Mallet finger

Disclaimer

These guidelines have been produced to guide clinical decision making for the medical, nursing and allied health staff of Perth Children’s Hospital. They are not strict protocols, and they do not replace the judgement of a senior clinician. Clinical common-sense should be applied at all times. These clinical guidelines should never be relied on as a substitute for proper assessment with respect to the particular circumstances of each case and the needs of each patient. Clinicians should also consider the local skill level available and their local area policies before following any guideline. 

Read the full PCH Emergency Department disclaimer.

Aim

To guide PCH ED staff with the assessment and management of mallet finger.

Background

  • 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.

Assessment

  • 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

Middle finger with mallet deformity

Investigations

  • X-ray of finger
  • Look for a dorsal avulsion fracture of the distal phalanx at DIP joint
X-ray of mallet finger
X-ray of mallet finger

Management

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 zimmer splint 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 showing number to indicate size.

Dorsal part of Stax splint. note the number that indicates the splint size

Volar aspect of Stax finger splint.

Volar aspect of Stax finger splint

Stax splint fixed with adhesive tape to the finger just distal to the PIP joint.

Fix finger just distal to PIP joint with a small adhesive strip (e.g. elastoplast)

Stax splint volar aspect fixed with adhesive tape

Volar aspect of Stax splint 

Kleinert modified dorsal finger splint (Mexican hat splint)

Zimmer splint (aluminium with foam back) cut to the appropriate length from finger tip to just distal to the PIP joint.

Zimmer splint (aluminium with foam backed splint) cut to the appropriate length, from the finger tip to just distal to the PIP joint

Foam padding removed from Zimmer splint in middle one third. Concave contour recreated by bending each end of the splint.

Removed middle third of foam padding with scissors. Bend each end of the splint to form a slight concave contour.

Patient holds the injured finger in hyperextension.

Instruct patient to hold the injured finger in hyperextension.

Splint affixed to the dorsum of the digit by two separate tapes.

Affix splint to dorsum of the digit with two separate tapings.


Bibliography

  1. Rebecca Bassett et al. Extensor tendon injury of the distal interphalangeal joint (mallet finger). Up To Date.
  2. R. G. Hart et al, The Kleinert modified dorsal splint for Mallet finger fracture. American Journal of Emergency Medicine 2005 (23), 145‐148

Endorsed by:  Director, Emergency Department   Date:  Mar 2018


 Review date:   Jun 2020


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