What is the acceptable amount of lateral displacement for a metatarsal shaft fracture?

Acceptable Lateral Displacement for Metatarsal Shaft Fractures

For metatarsal shaft fractures, surgical intervention is indicated when lateral displacement exceeds 3-4 mm or angulation exceeds 10 degrees in any plane. 1, 2

Assessment and Classification

Metatarsal fractures account for approximately one-third of all foot fractures, with the fifth metatarsal being the most commonly affected 3, 2. When evaluating these fractures, it's critical to assess:

• Degree of displacement (lateral, dorsal/plantar)
• Angulation
• Joint involvement
• Shortening
• Associated soft tissue injury

Imaging Considerations

• Initial evaluation should include 3-view radiographs of the foot (posteroanterior, lateral, and oblique views) 4
• CT may be necessary for complex fractures with articular involvement or when radiographs are equivocal 4
• MRI is preferred for suspected stress fractures with negative radiographs 4

Treatment Algorithm Based on Displacement

Conservative Management (Non-operative)

• Indicated for:
  • Nondisplaced fractures
  • Displacement <3-4 mm in horizontal plane
  • Angulation <10 degrees in any plane
  • Treatment consists of protected weight bearing in a cast shoe for 4-6 weeks 3

Surgical Management

• Indicated for:
  • Displacement >3-4 mm laterally
  • Angulation >10 degrees in any plane
  • Joint involvement with displacement >2 mm
  • Open fractures
  • Multiple fragments requiring anatomic reconstruction

Surgical Options

1. Percutaneous pinning: Suitable for most fractures of the lesser metatarsals 3
2. Open reduction and internal fixation (ORIF):
   • Plate fixation for markedly shortened and multifragment fractures 5
   • Screw fixation for long spiral fractures 5
   • Tension-band wiring for avulsion fractures 3

Special Considerations

Fifth Metatarsal Fractures

• Avulsion fractures of the fifth metatarsal require surgical treatment when displacement exceeds 2 mm or when more than 30% of the cubometatarsal joint is involved 1
• Jones fractures (transverse fractures at the metaphyseal-diaphyseal junction) require individualized treatment based on activity level and time to union 3

Potential Complications

• Malunion: Deformities in the axial plane (varus/valgus) are usually better tolerated than those in the coronal plane, especially plantar flexion deformity 6
• Non-union: More common in fifth metatarsal fractures, particularly in zone 3 (Jones fractures) 2
• Post-traumatic arthritis: Generally follows joint injury 2

Rehabilitation

• Early mobilization is recommended to prevent stiffness and improve functional outcomes 7
• Progressive weight bearing should be initiated based on fracture stability and healing
• Return to full activity typically ranges from 13-19 weeks depending on the rehabilitation protocol 7

Remember that malunited metatarsal fractures can be a frequent source of pain and disability 3, so proper initial management with adherence to the 3-4 mm displacement threshold is crucial for optimal outcomes.