What is the recommended initial management for an acute nondisplaced oblique fracture in the first metatarsal diaphysis?

Initial Management of Acute Nondisplaced Oblique Fracture of the First Metatarsal Diaphysis

For an acute nondisplaced oblique fracture of the first metatarsal diaphysis, initiate immediate immobilization with a short leg walking cast or controlled ankle motion (CAM) boot for 4-6 weeks with protected weight-bearing, followed by transition to a rigid-sole shoe. 1, 2

Diagnostic Confirmation

• Obtain standard three-view radiographs of the foot (anteroposterior, lateral, and oblique views) to confirm the diagnosis and assess fracture characteristics 3
• Verify that the fracture is truly nondisplaced with less than 3-4mm of displacement and less than 10 degrees of angulation, as these parameters determine conservative versus surgical management 4
• If radiographs are equivocal or clinical suspicion remains high despite negative initial films, consider repeat radiographs in 10-14 days or advanced imaging 3

Initial Immobilization Protocol

Week 0-4:

• Apply a short leg walking cast or CAM-walker boot immediately upon diagnosis 1, 2
• Allow protected weight-bearing as tolerated with the immobilization device 1
• The first metatarsal bears significant weight during gait, making immobilization critical to prevent displacement 1

Week 4-6:

• Continue immobilization in the cast or boot for a total duration of 4-6 weeks 1, 2
• Obtain follow-up radiographs at 4 weeks to ensure maintenance of fracture alignment and assess healing progress 1

Week 6 and beyond:

• Transition to a rigid-sole shoe for an additional 3-4 weeks after cast/boot removal 2
• Progressive return to normal activities as pain and clinical examination permit 1

Key Clinical Considerations

Why Conservative Management Works

• Nondisplaced metatarsal fractures heal reliably with conservative treatment, with excellent long-term functional outcomes reported in large cohorts 5
• The oblique fracture pattern, while potentially unstable, can be successfully managed nonoperatively when displacement is minimal 1, 4

Red Flags Requiring Surgical Intervention

• Displacement greater than 3-4mm 4
• Angulation exceeding 10 degrees 4
• Failure to maintain reduction on follow-up radiographs 1
• Involvement of more than 30% of the metatarsocuneiform joint (if fracture extends proximally) 4

Common Pitfalls to Avoid

• Do not rely on pain alone to guide weight-bearing progression; patients with neuropathy or high pain tolerance may overload the fracture prematurely 1
• Ensure adequate immobilization compliance; removable boots allow for non-adherence, which can lead to delayed union or malunion 3
• Monitor for rotational deformity, particularly with oblique fracture patterns, through serial clinical examination and radiographs 6
• Delayed unions occur in approximately 1-2% of cases treated conservatively, requiring extended immobilization or potential surgical intervention 5

Follow-Up Schedule

• Week 4: Clinical examination and repeat radiographs to confirm maintained alignment 1
• Week 8: Assess for clinical and radiographic union 7
• Week 12: Final assessment if healing is delayed; consider advanced imaging or orthopedic referral if symptomatic 5

Expected Healing Timeline

• Radiographic union typically occurs by 7-9 weeks with appropriate immobilization 7
• Return to full activities averages 8-10 weeks from injury 7, 5
• Long-term functional outcomes are excellent with FAAM scores averaging 95.5 for activities of daily living 5