What degree of displacement requires operative intervention for a metacarpal shaft fracture?

Metacarpal Shaft Fracture Displacement Guidelines for Operative Intervention

Metacarpal shaft fractures with displacement greater than 30 degrees of angulation, shortening greater than 5mm, or any rotational deformity require operative intervention. 1

Displacement Parameters Requiring Surgery

Metacarpal shaft fractures can be managed conservatively or surgically depending on the degree of displacement. The following parameters indicate the need for surgical intervention:

• Angular displacement:

  • 30 degrees of angulation 2, 1

  • This applies particularly to dorsal/palmar angulation

• Shortening:

  • 5mm of shortening 2, 1

  • Excessive shortening leads to functional deficit and cosmetic deformity

• Rotational deformity:

  • Any rotational displacement >10 degrees 2
  • Even minor rotational deformity can cause digital overlap during flexion

• Other indications for surgery:

  • Articular incongruency/intra-articular extension
  • Multiple fractures (serial fractures)
  • Open fractures
  • Significant soft tissue trauma

Assessment of Displacement

Proper radiographic evaluation is essential for accurate assessment:

• Standard 3-view radiographic examination (PA, lateral, and oblique) is typically sufficient 3
• An internally rotated oblique projection increases diagnostic yield for metacarpal fractures 3
• Evaluate for:
  • Degree of angulation in both PA and lateral planes
  • Shortening (measured in mm)
  • Rotational deformity (clinical examination)
  • Articular involvement

Management Algorithm

1. Conservative management is appropriate for:

   • Angulation <30 degrees
   • Shortening <5mm
   • No rotational deformity
   • No articular involvement
   • No significant soft tissue trauma

2. Surgical intervention is indicated for:

   • Angulation >30 degrees
   • Shortening >5mm
   • Any rotational deformity >10 degrees
   • Articular involvement
   • Multiple/serial fractures
   • Open fractures

Surgical Options

When operative intervention is indicated, options include:

• Low-profile mini plates and screws - provides stable fixation allowing early mobilization 4
• Intramedullary pinning - less invasive but may result in more rotational deformity 5
• K-wire fixation - useful for simple fracture patterns

Recent evidence suggests that locking plates may provide better outcomes than intramedullary pinning for metacarpal shaft fractures, with improved range of motion, grip strength, and less rotational deformity 5.

Important Considerations

• Closed reduction of displaced fractures of the fifth metacarpal (boxer's fracture) is often unsuccessful, with only 15% success rate 2
• Immobilization beyond 3-4 weeks is not necessary and may lead to stiffness 2
• Early mobilization is crucial for optimal functional outcomes
• Hand stiffness is one of the most functionally disabling adverse effects of hand fractures 3

Caveats and Pitfalls

• Avoid prolonged immobilization even in conservatively treated fractures
• Be aware that some studies suggest no difference in outcomes between operatively and non-operatively treated metacarpal shaft fractures, particularly for the 5th metacarpal 6
• Consider patient-specific factors such as occupation, hand dominance, and functional demands
• Recognize that excessive surgical intervention for minimally displaced fractures may not improve outcomes and could potentially lead to complications

Remember that the goal of treatment is to restore function rather than achieve perfect radiographic alignment. The functional impact of the deformity should guide treatment decisions.