Conservative Management Thresholds for Base of Fifth Metacarpal Fractures
Base of fifth metacarpal fractures can be managed conservatively when there is no joint displacement, no malrotation, angulation less than 30 degrees, and shortening less than 5 mm. 1
Acceptable Parameters for Non-Operative Treatment
Angulation Limits
- Maximum acceptable angulation: 30 degrees 1, 2
- Fractures with angulation beyond 30 degrees should be considered for surgical intervention 1
- Some literature suggests up to 70 degrees may be acceptable for fifth metacarpal neck fractures specifically (boxer's fractures), though this is controversial 3
Displacement and Other Criteria
- Maximum acceptable shortening: 5 mm 1, 2
- No rotational displacement (or less than 10 degrees if any rotation present) 2
- No articular incongruency or intra-articular displacement 2
- No significant soft tissue trauma 2
Important Clinical Distinction
Base fractures are inherently unstable and behave differently than neck fractures. 4 Base of fifth metacarpal fractures (the focus of your question) are relatively uncommon and more prone to instability compared to the more common neck fractures (boxer's fractures) 4. These fractures may result in pain, functional disability, and osteoarthritic changes if inadequately reduced 4.
Treatment Approach When Conservative Management is Appropriate
Immobilization Strategy
- Short-period casting in full finger extension with 60-90 degrees of flexion at the metacarpophalangeal joint 1
- Immobilization should not exceed 3-4 weeks 2
- Early functional treatment is preferred for stable, non-displaced fractures 1
Follow-up Monitoring
- Regular radiographic assessment is essential to monitor for displacement 5
- Clinical vigilance for malrotation, which can cause significant functional impairment
Critical Caveat
Closed reduction of displaced base fractures is often unsuccessful, and inadequate reduction leads to poor outcomes. 4, 1 If the fracture exceeds the conservative management thresholds listed above, surgical intervention with reduction and pinning should be strongly considered to restore articular congruity and prevent long-term complications 4.