Trauma Tuesday!Metacarpal Fractures
Why do we care so much about a few small bones in the hand? Because missed injuries can lead to permanent disabilities--we (as well as our patients) need our hands for pretty much everything.
How to assess for these injuries? Do your typical hand exam but pay special attention to:
Rotational alignment! Have the patient flex at the MCP and PIP, forming a loose fist with the DIPs extended (as in the figure below, to the left). The axis of each digit should merge near mid wrist. Rotational malalignment will cause deviation of this axis for the injured digit.
Rotational malalignment is usually an indication for operative repair, so be sure to check for it.
Don't forget: Any open wound over the MCP should alert you to the possibility of a "fight bite"--usually require exploration or washout. This needs EMERGENT ortho evaluation.
Diagnosis
Get X-rays - AP, lateral, and oblique views; pay special attention to the lateral as this is what you will use to measure angulation.
For the quick and dirty: acceptable shaft angulation is 40° for 5th MC, 30° for 4th MC, 20° for 3rd MCP, and 10° for 2nd. Reduce if there is greater angulation.
Management
NONOPERATIVE: For stable fractures, those without rotational deformities, and those with acceptable angulation and shortening (usually 2-5mm for each shaft) => nonoperative repair:
Reduce a dorsally angulated neck fracture before splinting, usually done via the Jahss technique. (https://youtu.be/40irKoUJqsM)
For MCP head/neck/shaft fractures, radial or ulnar gutter splint depending on which MCP is injured. For MCP base fractures, wrist splint.
OPERATIVE: For open fractures, intra-articular fractures, fractures with rotational malalignment, significantly displaced or angulated fractures, or in the event of multiple MCP fractures => operative repair
Err on the side of prompt orthopedic follow up.
Sources
https://emergencymedicinecases.com/episode-29-hand-emergencies/