Minor Hand Injuries
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
Figure 1. X-ray of mallet finger injury
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.
Figure 2. X-ray of Boxer’s fracture
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
Figure 3. X-ray of Rolando’s Fracture
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
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
Domingues, Moises. Boxer Fracture (Fifth Metacarpal Neck Fracture). https://step1.medbullets .com/msk/107089/boxer-fracture-fifth-metacarpal-neck-fracture
Krueger, Chad. Base of Thumb Fractures. https://www.orthobullets.com/hand/6036/base-of -thumb-fractures
Sheth, Ujash. Mallet Finger. https://www.orthobullets.com/hand/6014/mallet-finger