What is the recommended treatment for a nondisplaced fifth metatarsal base fracture?

Treatment of Nondisplaced Fifth Metatarsal Base Fracture

The recommended treatment for nondisplaced fifth metatarsal base fractures is conservative management with protected weight-bearing using either a controlled ankle motion (CAM) walker boot or a hard-soled shoe for 6-8 weeks. 1

Diagnosis

• Initial evaluation should include three standard radiographic views (anteroposterior, lateral, and mortise) that include the base of the fifth metatarsal bone 2
• Weight-bearing radiographs, if possible, provide important information about fracture stability 2
• The Ottawa Ankle Rules should be applied to determine the need for radiographs in patients with ankle trauma 2

Classification

Fifth metatarsal base fractures are typically classified by zone:

• Zone 1: Avulsion fractures of the tuberosity (most common) 3, 4
• Zone 2: Fractures at the metaphyseal-diaphyseal junction 4
• Zone 3: Proximal diaphyseal fractures (Jones fractures) 3, 4

Treatment Algorithm for Nondisplaced Fifth Metatarsal Base Fractures

Conservative Management (First-line treatment)

• Protected weight-bearing with either:
  • CAM walker boot for 6-8 weeks (shows faster bone healing compared to hard-soled shoes) 1
  • Hard-soled shoe for 6-8 weeks (similar functional outcomes to CAM boot) 1
• Regular radiographic assessment to ensure proper healing and alignment 5
• Progressive weight-bearing as tolerated after initial immobilization period 5

Follow-up Care

• Radiographic follow-up at 4-6 weeks to assess healing 5, 1
• Average time for bone healing: 7-9 weeks 1
• Average time to return to prior level of activities: 8-10 weeks 1

Special Considerations

Indications for Surgical Referral

• Fractures that are displaced more than 2mm 4
• Fractures involving more than 30% of the cubometatarsal articulation surface 3, 4
• Comminuted fractures 3
• Fractures with delayed union or nonunion 3, 6
• Jones fractures (Zone 3) with displacement or in high-performance athletes 4

Rehabilitation Protocol

• Early introduction of physical training and muscle strengthening followed by balance training after immobilization period 5
• Avoid prolonged immobilization to prevent stiffness and muscle atrophy 5

Potential Complications

• Delayed union, especially in Jones fractures (Zone 3) 3, 4
• Nonunion requiring surgical intervention 6
• Chronic pain and muscle atrophy with prolonged immobilization 3

Treatment Efficacy

• Conservative treatment with either CAM walker boot or hard-soled shoe shows similar clinical and functional outcomes 1
• CAM walker boot demonstrates slightly faster bone healing (7.2 weeks) compared to hard-soled shoes (8.6 weeks) 1
• Percutaneous fixation without fracture site preparation has shown excellent results for nonunions 6

Common Pitfalls to Avoid

• Failing to include the base of the fifth metatarsal in ankle radiographs 2
• Unnecessary ordering of foot radiographs when ankle radiographs already include the fifth metatarsal base 2
• Overlooking displacement that may require surgical intervention (>2mm) 4
• Inadequate immobilization leading to delayed healing or nonunion 3