5th metacarpal fracture (Boxer’s fracture)

What is it?

A boxer’s fracture is a fracture of the fifth metacarpal bone of the hand, at the metacarpal neck. This is the bone associated with the little finger. When fractured, usually after punching an object like a boxer, it is often angulated and/or displaced requiring reduction and or surgical fixation.

Relevant Anatomy

The fifth metacarpal gives structure to the medial boarder of the hand and can be felt below the skin. The lumbrical and interosseous muscles, attached to the fifth metacarpal, cause the fracture to angulate apex dorsal, towards the back of the hand. 

A boxer’s fracture is usually the result of punching a hard object with an unprotected fist. The fifth metacarpal bone is loaded along its longitudinal axis through the metacarpal head at the metacarpalphalangeal joint (MCPJ), and fractures in the shaft of the bone. A combination of this axial load and the deforming forces of the lumbrical and interosseous muscles cause an apex dorsal angulation.

Examination

Examination of a boxer’s fracture focuses on determining the orientation of the fracture and its effect on the rotation of the small finger. The examination needs to make sure that there is no overlap of the small finger on the ring finger or significant divergence from the ring finger when compared to the other side. A neurovascular examination of the hand and small finger is performed to make sure that the nerves and vessels to the finger are uninjured. From triage, where a fracture is suspected, order an x-ray if possible. Ensure adequate pain relief and offer a sling. Cover any wounds with a damp dressing.

Treatment

  • Analgesia
  • Plaster of Paris – Volar slab in Edinburgh position
  • Virtual fracture clinic

Prognosis

Over angulation of a boxer’s fracture can lead to a prominent metacarpal head felt in the palm of the hand, and cause decreased grip strength. Further, a rotationally malaligned metacarpal can cause a grasp abnormality. Splinting or casting of the hand in a position other than intrinsic plus position can lead to an extension contracture at the MCP joint and dysfunction of the hand.

* * * * *

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

A WordPress.com Website.

Up ↑

%d bloggers like this: