Treatment of Acute Nondisplaced Intra-articular Fracture of the Fifth Metatarsal Base
For an acute nondisplaced intra-articular fracture involving the base of the fifth metatarsal, conservative treatment with a controlled ankle motion (CAM) walker boot for 6-8 weeks is the recommended approach to optimize healing while minimizing morbidity and preserving function.
Fracture Classification and Assessment
Fifth metatarsal base fractures can be classified based on location:
- Zone 1 (tuberosity/styloid avulsion fractures)
- Zone 2 (Jones fractures at metaphyseal-diaphyseal junction)
- Zone 3 (proximal diaphyseal stress fractures)
The intra-articular fracture at the base of the fifth metatarsal described in this case would typically be classified as a Zone 1 fracture that extends into the articulation with the cuboid bone.
Key Assessment Points:
- Evaluate for displacement (>2mm would require special consideration)
- Assess percentage of articular surface involvement (>30% of the cubo-metatarsal articulation may require surgical referral)
- Check for comminution (multiple fragments)
- Confirm weight-bearing ability
Treatment Algorithm
1. Initial Management
- Immobilization: CAM walker boot is superior to postoperative sandals or athletic shoes for offloading the fifth metatarsal base 1
- Weight-bearing status: Immediate full weight-bearing is acceptable for nondisplaced fractures 2
- Pain control: NSAIDs as needed
2. Follow-up Care
- Radiographic evaluation at 4 weeks to assess healing
- Continue immobilization until clinical and radiographic healing (typically 6-8 weeks)
- Transition to supportive footwear after adequate healing
3. Expected Outcomes
- Return to work: Approximately 2-3 weeks (17 ± 12 days) 2
- Return to sports/full activities: Approximately 7-8 weeks (53 ± 22 days) 2
- Bone healing: Faster with CAM walker boot (7.2 weeks) compared to hard-soled shoes (8.6 weeks) 3
Evidence-Based Rationale
Research demonstrates that CAM walker boots more effectively offload the fifth metatarsal during gait activities compared to postoperative sandals or standard athletic shoes 1. This reduced pressure at the fracture site promotes faster healing and minimizes the risk of displacement or nonunion.
A comparative study showed that while both CAM walker boots and hard-soled shoes achieved similar functional outcomes, the CAM walker boot demonstrated significantly faster bone healing (7.2 weeks vs 8.6 weeks) 3. This faster healing time can reduce the overall morbidity associated with prolonged immobilization.
Importantly, research has shown excellent outcomes with functional treatment (immediate full weight-bearing) for both displaced (<2mm) and nondisplaced fifth metatarsal base fractures, even with intra-articular involvement 2. This suggests that conservative management is appropriate for most nondisplaced intra-articular fractures of the fifth metatarsal base.
Special Considerations and Pitfalls
Indications for Orthopedic Referral:
- Fractures with >2mm displacement
- Comminuted fractures
- Fractures involving >30% of the articular surface
- Signs of delayed union after 6-8 weeks of conservative treatment
Common Pitfalls to Avoid:
- Inadequate immobilization: Failure to properly immobilize can lead to displacement and nonunion
- Premature return to activities: Returning to sports or high-impact activities before adequate healing increases risk of refracture
- Missing associated injuries: Always assess for concomitant ankle ligament injuries or other foot fractures
- Overlooking delayed union: If healing is not progressing as expected by 6-8 weeks, consider orthopedic referral for possible surgical intervention
By following this treatment approach, most patients with nondisplaced intra-articular fractures of the fifth metatarsal base can expect excellent functional outcomes with minimal morbidity and a high likelihood of returning to pre-injury activity levels.