Episode 158.0 – Boxer’s Fracture

Podcast Video

Show Notes

Background:

• 40% of all hand fractures
• A metacarpal fracture can occur at any point along the bone (head, neck, shaft, or base)
• “Boxer’s” fractures classically at neck
• Most common mechanism: direct axial load with a clenched fist
• Most common metacarpal injured is the 5^th
• A majority of these injuries are isolated injuries, closed and stable

Examination:

• Ensure that this is an isolated injury
• May note a loss of knuckle contour or shortening
• A thorough evaluation of the skin is important
  • Patients may also have fight bites and require irrigation and antibiotics
• Tender along the dorsum of the affected metacarpal
• Evaluate the range of motion as the commonly seen shortening results in extension lag
  • For every 2 mm of shortening there is going to be a 7 degree decrease in ability to extend the joint
• Check rotational alignment of digits with the MCP and PIP at 50% flexion.
  • Partially clench their fist and ensure that the axis of each digit converges near the scaphoid pole / mid wrist

• Deformity is often seen due to the imbalance of volar and dorsal forces
  • Dorsal angulation
• AP, lateral and oblique views should be obtained on XR
• The degree of angulation is estimated with the lateral view
  • NB: Normal angle between the metacarpal head and neck is 15 degrees

Management:

• Most may be splinted with an ulnar gutter splint
  • Must be closed, not significantly angulated, and not malrotated
• When splinting, place the wrist in slight extension, MCP (knuckles) at 90 degrees and the DIP and PIP in a relaxed, slightly flexed position
• A closed reduction is indicated if there is significant angulation
  • “20, 30, 40” rule
    • If angulation is more than:
      • 20 in the middle finger metacarpal
      • 30 in the ring finger metacarpal
      • 40 in the pinky finger metacarpal
    • Analgesia with a hematoma block or ulnar nerve block
    • Reduction technique: https://www.aliem.com/2013/01/trick-of-trade-reducing-metacarpal/

Referral:

• May have mild deformity or decreased functionality and strength in hand grip after this injury
• Emergent evaluation if:
  • Open fracture
  • Neurovascular compromise

Follow up:

• Refer to hand specialist
  • Within 1 week if fractures of 4^thand 5^thmetacarpals with angulation
  • 3 to 5 days if the 2^ndand 3^rd metacarpalsare affected
  • Immobilized for three to four weeks in splint
  • Healing may take up to six weeks

Take Home Points:

• This is one of the most common fractures we will see as emergency physicians
• When evaluating these patients, ensure that this are no other more severe, life-threatening injuries, and pay particular attention to the skin exam so that you do not miss a fight-bite
• Reductions may be required if there is significant angulation, which is guided by the 20, 30, 40 rule
• Finally, emergent specialist evaluation is indicated if there is an open fracture or evidence of neurovascular compromise