Mallet Finger

Mechanism: 

• Forced flexion of an extended DIP joint (often being struck by a ball or other object) causing rupture of the extensor tendon at the level of the distal phalanx +/- avulsion fracture of the distal phalanx 

Clinical Presentation: 

• DIP joint held in flexion with inability to fully extend the finger tip

Treatment:

• Often can be managed non-operatively with a volar splint across the DIP or commercially made mallet finger splints

• Instruct the patient that they must leave the splint on for six weeks, as each time the joint flexes the clock “resets” on the injury healing

• If patients must change the splint they should be instructed to place their hand palm down on a flat surface while changing the splint to ensure that no flexion of the joint occurs

• If left untreated a swan neck deformity will likely develop

Boxer’s Fracture

Mechanism:

• Fracture of the head of the 5th metacarpal caused by an axial load most often due to punching a person or object, hence the name.

Clinical Presentation: 

• Pain and swelling along the distal 5th metacarpal associated with volar angulation or “loss of 5th knuckle”

• Be sure to evaluate for “fight bites” if the injury is from punching another person

Treatment: 

• Almost always needs referral to orthopedics for surgical correction

• Indications for emergent reduction in the ED include any rotational injury or angulation >40 deg

• Splinting can be accomplished either with an ulnar gutter splint or forearm volar splint

Bennett’s and Rolando’s Fractures

Mechanism:

• Bennett’s fracture is an intra-articular fracture of the base of the thumb generally caused by axial loading, also referred to as a Type I thumb fracture

• Rolando’s fracture is a comminuted version of Bennett’s, also called a Type II thumb fracture, with a worse prognosis than Bennett’s

• Often accompanied by subluxation or dislocation of the CMC joint

Clinical Presentation: 

• Pain, swelling, and ecchymosis over the base of the thumb

• Important to differentiate from tenderness over the more distal MCP joint which could indicate a different injury such a Gamekeeper’s Thumb

Treatment: 

• Urgent referral to orthopedics (3-5d), as the vast majority will require surgery 

• Do not attempt reduction as these fractures are intra-articular

Author: Brett Murray, MD is a fourth year emergency medicine resident and chief at Brown University/Rhode Island Hospital.

Faculty Reviewer: Shideh Shafie, MD is assistant professor of emergency medicine and attending physician at Brown University/Rhode Island Hospital.

REFERENCES

1. Bassett, Rebecca. Extensor tendon injury of the distal interphalangeal joint (mallet finger). https://www.uptodate.com/contents/extensor-tendon-injury-of-the-distal-interphalangeal-joint-mallet-finger?search=mallet%20finger&source=search_result&selectedTitle=1~21&usage_type=default&display_rank=1

2. Domingues, Moises. Boxer Fracture (Fifth Metacarpal Neck Fracture). https://step1.medbullets .com/msk/107089/boxer-fracture-fifth-metacarpal-neck-fracture

3. Krueger, Chad. Base of Thumb Fractures. https://www.orthobullets.com/hand/6036/base-of -thumb-fractures

4. Sheth, Ujash. Mallet Finger. https://www.orthobullets.com/hand/6014/mallet-finger