Mallet finger

The patient presents with inability to actively extend the distal interphalangeal joint (DIPJ). Usually follows, forced flexion of an extended finger avulsing the extensor tendon or bony attachment from the base of the distal phalanx. It is important to x-ray all mallet fingers to exclude a bony mallet, as it sometimes involves a considerable part of the articular surface of the distal phalanx.

Mallet fingers occur commonly in two forms:

• Soft tissue avulsions, which can be treated conservatively with closed splinting.
• Bony mallet, an attempt at closed reduction and splinting should be tried.
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Indication for surgical intervention include large fragments ( > 30% of the joint surface) that are rotated, or  persistent subluxation of the DIPJ.

• Large fragment	Subluxed Joint

Classification

Soft tissue versus bony mallet is very useful, however a more formal classification has been proposed by Doyle

• Type I: closed or blunt trauma with loss of tendon continuity with or without a small avulsion fracture
• Type II: laceration at or proximal to the distal interphalangeal joint with loss of tendon continuity
• Type III: deep abrasion with loss of skin, subcutaneous cover, and tendon substance
• Type IV: (A) transepiphyseal plate fracture in children; (B) hyperflexion injury with fracture of articular surface of 20% to 50%; and (C) hyperextension injury with fracture of the articular surface usually greater than 50% and with early or late volar subluxation of the distal phalanx.

Management Specifics

Closed Splinting

• Must be continuous and the skin on the dorsum of the finger must be inspected and protected from undue pressure and or maceration. If the skin condition is poor stabilization with a k wire is an option.
• The DIPJ must be kept in extension at all times. Continuous splinting for 6 weeks  followed by night splinting for 2-6 weeks
• Whatever method you use to keep the DIPJ in extension avoid over/hyperextending the DIPJ to the point that the skin blanches. Skin blanching shows the blood flow to the skin is being impaired.

Surgical technique

Surgery is indicated for bony mallet's where the joint is subluxed or the fragment involves a large percentage of the joint surface.

Open reduction is technically demanding. Closed reduction and percutaneous fixation has also been described.

Once reduced several methods of fixation have been described see references below.

Doyle JR: Extensor Tendons-Acute Injuries. In Green DP (ed). Operative Hand Surgery. Ed 3. New York, Churchill-Livingstone 2:1925-1954, 1993

Sarifakioglu, Nedim M.D.. Aslan, Gurcan M.D.. Bingul, Ferruh M.D.. USING A SIMPLE AND INEXPENSIVE DEVICE IN ASSOCIATION WITH TYPE IV MALLET FINGER. Plastic & Reconstructive Surgery. 110(7):1807-1808, December 2002.
 

Tetik, Cihangir MD. Gudemez, Eftal MD. Modification of the Extension Block Kirschner Wire Technique for Mallet Fractures. Clinical Orthopaedics & Related Research. 1(404):284-290, November 2002.
 

Rockwell, W. Bradford M.D.. Butler, Peter N. M.D.. Byrne, Bruce A. M.D.. Extensor Tendon: Anatomy, Injury, and Reconstruction. Plastic & Reconstructive Surgery. 106(7):1592-1603, December 2000.

Okafor, B.. Mbubaegbu, C.. Munshi, I.. Williams, D. J.. Mallet Deformity of the Finger: Five-Year Follow-Up of Conservative Treatment. Journal of Bone & Joint Surgery - British Volume. 79-B(4):544-547, July 1997.
 

reviewed 31 patients,  mean five years after mallet deformity of the finger had been treated with a thermoplastic splint. Intra-articular fractures were present in 35% of patients. Osteoarthritic changes had developed in 48%, most in association with fracture, and 29% had a swan-neck deformity. There was a loss of extension greater than 10 degrees in 35%; the average deficit at the interphalangeal joint was 8.3 degrees and the average flexion arc was 48.5 degrees.

Despite these findings, patient satisfaction was generally high, with little evidence of functional impairment.

Lubahn, John D. MD. Hood, John M. MD. Fractures of the Distal Interphalangeal Joint. Clinical Orthopaedics & Related Research. (327):12-20, June 1996.

Last updated 11/09/2015