What is the treatment for an oblique fracture at the neck of the fourth metacarpal?

Treatment of Oblique Fracture at Neck of Fourth Metacarpal

The treatment of oblique fractures at the neck of the fourth metacarpal should be determined by fracture stability, with non-displaced or minimally displaced fractures managed conservatively and unstable fractures requiring surgical intervention. 1, 2

Initial Assessment

• Initial evaluation requires 3-view radiographs of the hand (posteroanterior, lateral, and 45° semipronated oblique) to confirm diagnosis and assess fracture characteristics 1, 2
• Additional imaging with CT may be considered if radiographs are equivocal to better visualize fracture pattern 1
• Assessment should evaluate for:
  • Degree of angulation (>30° indicates instability)
  • Shortening (>5mm indicates instability)
  • Rotational deformity
  • Joint involvement 3

Treatment Algorithm

Conservative Management

Conservative treatment is appropriate for:

• Non-displaced fractures
• Stable fractures without malrotation
• Angulation <30° and shortening <5mm 3

Conservative treatment options include:

• Short arm cast with the metacarpophalangeal (MCP) joint flexed at 60-90° for 3-4 weeks 3
• Twin-tape fixation after soft tissue swelling subsides to allow earlier functional treatment 3
• Early functional treatment for stable fractures to prevent stiffness 4

Surgical Management

Surgical intervention is indicated for:

• Unstable fractures with angulation >30°
• Shortening >5mm
• Rotational deformity
• Open fractures
• Multiple metacarpal fractures 5, 3

Surgical options include:

1. Percutaneous Kirschner wire fixation:

   • Most commonly used due to versatility and availability
   • Appropriate for most unstable neck fractures
   • Disadvantages include lack of rigid fixation and potential pin track infection 6, 7

2. Intramedullary fixation:

   • Particularly useful for boxer's fractures (5th metacarpal neck)
   • Can be used for 4th metacarpal neck fractures with similar biomechanics 3

3. Plate and screw fixation:

   • Reserved for large, oblique fractures that require more rigid fixation
   • Provides excellent stability but requires more extensive dissection 5, 6

4. Interfragmentary screws:

   • Appropriate for long oblique fractures
   • Provides compression across fracture site 6, 7

5. Modified bone tie technique:

   • Can be considered for unstable oblique fractures
   • Provides interfragmentary compression with less extensive dissection than plating 7

Post-Treatment Management

• Early range of motion is critical to prevent stiffness and optimize functional outcomes 4
• For surgically treated fractures, protected motion can begin as soon as stable fixation is achieved 6
• For conservatively treated fractures, early functional treatment should be initiated once soft tissue swelling subsides 3
• Regular follow-up with serial radiographs to ensure proper healing and alignment 1

Potential Complications

• Malunion leading to decreased grip strength and functional limitations
• Stiffness from prolonged immobilization
• Rotational deformity causing finger overlap
• Hardware-related complications if surgical fixation is used 6, 4

Special Considerations

• The 4th metacarpal has less mobility than the 5th, so angulation tolerance is lower
• Oblique fractures at the neck are inherently less stable than transverse fractures
• Functional outcomes depend heavily on early mobilization whenever possible 4
• Closed reduction of significantly displaced fractures is often unsuccessful and may require surgical intervention 3