Mallet finger

Mallet finger
Mallet finger
Other names	Hammer finger, extensor tendon injury at the DIP joint, baseball finger
	Mallet finger of the middle finger. The tip of the finger bends downwards while the other fingers stay straight.
Specialty	Emergency medicine, sports medicine, plastic surgery
Symptoms	Inability to extend the finger tip, pain and bruising of the finger
Causes	Trauma resulting in over bending of the finger tip
Diagnostic method	Based on symptoms, X-rays
Treatment	Splinting for 8 weeks, surgery
Prognosis	6 to 10 weeks for healing
Frequency	Relatively common

A mallet finger, also known as hammer finger or PLF finger or Hannan finger, is an extensor tendon injury at the farthest away finger joint.^[2] This results in the inability to extend the finger tip without pushing it.^[3] There is generally pain and bruising at the back side of the farthest away finger joint.^[3]

A mallet finger usually results from overbending of the finger tip.^[3] Typically this occurs when a ball hits an outstretched finger and jams it.^[3] This results in either a tear of the tendon or the tendon pulling off a bit of bone.^[3] The diagnosis is generally based on symptoms and supported by X-rays.^[3]

Treatment is generally with a splint that holds the fingertip straight continuously for 8 weeks.^[3] The middle joint is allowed to move.^[3] This should be begun within a week of the injury.^[3] If the finger is bent during these weeks, healing may take longer.^[3] If a large piece of bone has been torn off surgery may be recommended.^[3] Without proper treatment, the finger may be permanently deformed.^[2]

Diagnosis

The diagnosis is generally based on symptoms and supported by X-rays.^[3] The injury can be accompanied by swelling and ecchymosis.^[4]

$X-ray showing fracture at the insertion of the extensor tendon$

X-ray showing fracture at the insertion of the extensor tendon
$A mallet finger without an associated fracture$

A mallet finger without an associated fracture

Treatment

The management goal is to restore extension of the joint.^[5] Treatment is generally with a splint that holds the first joint of the finger straight continuously for 8 weeks.^[3] This should begin within a week of the injury.^[3] The splint may be worn just at night for a few additional weeks after this.^[3] The splint acts to immobilize flexing of the joint.

Surgery generally does not improve outcomes.^[2] It may be required if the finger cannot be straightened by pushing on it or the break has pulled off more than 30% of the joint surface.^[2] Surgery may be preferred over the use of a splint if a child is non-compliant.^[5] If the problem has been present a long time surgery may also be required.^[6] An open fracture may be another reason. Surgery will put the finger in a neutral position and drill a wire through the distal interphalangeal joint (DIP) to the proximal interphalangeal joint (PIP), forcing immobilization.

An example of a splint for mallet finger.
Lateral view of a splint for mallet finger. Note the lower side is open to allow the second joint to flex.

References

^ Harris, Peter; Nagy, Sue; Vardaxis, Nicholas (2014). Mosby's Dictionary of Medicine, Nursing and Health Professions (eBook) (Australian & New Zealand ed.). Elsevier Health Sciences. p. 1050. ISBN 978-0729581387.
^ ^a ^b ^c ^d ^e ^f Leggit, JC; Meko, CJ (1 March 2006). "Acute finger injuries: part I. Tendons and ligaments". American Family Physician. 73 (5): 810–16. PMID 16529088.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s ^t ^u "Mallet Finger (Baseball Finger)". OrthoInfo - AAOS. March 2015. Archived from the original on 23 October 2017. Retrieved 15 October 2017.
^ Buttaravoli, Philip (2012). "Extensor Tendon Avulsion—Distal Phalanx: (Baseball or Mallet Finger)". Minor Emergencies (Third ed.). Saunders. pp. 415–418. doi:10.1016/B978-0-323-07909-9.00108-2. ISBN 9780323245623.
^ ^a ^b S.Lin, James; Julie BalchSamora (November 2018). "Outcomes of Splinting in Pediatric Mallet Finger". The Journal of Hand Surgery. 43 (11): 1041.e1–1041.e9. doi:10.1016/j.jhsa.2018.03.037. PMID 29776724.
^ Tuttle, HG; Olvey, SP; Stern, PJ (April 2006). "Tendon avulsion injuries of the distal phalanx". Clinical Orthopaedics and Related Research. 445: 157–68. doi:10.1097/01.blo.0000205903.51727.62. PMID 16601414.