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Mallet Finger M20.019 736.1

Mallet Finger xray

Finger extensor mechanism image

Stax Splint

synonyms: baseball finger, drop finger, finger extensor tendon avulsion

Mallet Finger ICD-10

Mallet Finger ICD-9

  • 736.1(acquired)
  • 755.59(congenital)

Mallet Finger Etiology / Epidemiology / Natural History

  • Disruption of the extensor mechanism at the level of the DIP joint.
  • Caused by forced flexion of the extended DIP joint.
  • Usually involves long, ring or small fingers (Brzezienski MA Hand Clin 1995;11:373)
  • Without treatment the terminal extensor tendon migrates proximally, increasing extensor tone at the PIP joint which can lead to a swan neck deformity

Mallet Finger Anatomy

  • DIP extension is provided by the the conjoined lateral bands which insert into the base of the distal phalanx
  • Conjoined lateral bands are made up of the lateral slips of the extrinsic extensor tendon and the lateral bands from the intrinsic interosseous and lumbrical muscles.

Mallet Finger Clinical Evaluation

  • Pain, inability to extend DIP joint

Mallet Finger Xray / Diagnositc Tests

  • P/A, oblique, and lateral radiographs of finger. Often normal, may show avulsion fragment, or articular fracture.

Mallet Finger Classification / Treatment

  • Closed No fracture or fracture involving <1/3 of the articular surface = involved digit immobilized in full extension or hyperextension across the DIP joint. PIP joint is generally not immobilized. Maintain for 8weeks, followed by nightime splint use for 2-3 weeks. Splinted period must be restarted if patient inadvertently flexes finger during treatment period. (Okafor B, JBJS 1997;79B:544) Full time extension splinting for 8 wks even up to 6 months after terminal extensor tendon rupture leads to good results in the vast majority of patients.  Surgery is rarely necessary.
  • Open = lacerations are generally repaired with running suture reapproximating both skin and tendon +/-longintudinal K-wire fixation of DIP joint in extension.
  • Closed with fracture >1/3 of articular surface / DIP joint subluxation = closed reduction with Extension Block Pinning 26756. (Tetik C, Clin Orthop 2002;404:284-290), (Pegoli L, J Hand Surg 2003;28B:15)
  • Chronic injuries (generally those > 6months old, or have failed extension splinting) = consider tenodermodesis (Iselin F, J Hand Surg 1977;2Am:118); oblique retinacular ligament reconstruction (Kleinman WB, J Hand Surg 1994;9Am:399); DIP fusion

Mallet Finger Associated Injuries / Differential Diagnosis

Mallet Finger Complications

  • skin maceration/ulceration
  • tape allergy
  • infection
  • nail plate deformity
  • hardware failure
  • DIP joint deformity
  • pain

Mallet Finger Follow-up Care

  • Post-op /Initial: Place in alumifoam extension / clamshell / Stack splint. Elevation.
  • 7-10 Days: xray to ensure reduction is maintained. Continued splint, activity modifications. Immobilize as few joints as necessary.
  • 6 Weeks: Remove k-wire, wean from splint use as soon as callus is visible on xray. Continue activity modifications. Agressive DIP ROM.
  • 3 Months: Resume full activities. Assess ROM.
  • 1Yr: assess outcomes / follow-up xrays.

Mallet Finger Review References

  • Bendre AA, JAAOS 2005;13:336
  • Wehbe MA, Schneider LH: Mallet fractures.  J Bone Joint Surg 1984;66A:658-669.
  • Stern PJ, Kastrup JJ: Complications and prognosis of treatment of mallet finger.  J Hand Surg 1988;13A:329-334.
  • Garberman SF, Diao E, Peimer CA: Mallet finger: Results of early versus delayed closed treatment.  J Hand Surg 1994;19A:850-852.
  • Rockwood and Green's Fractures in Adults 6th ed, 2006°