What degree of angulation in distal radial and ulnar fractures requires reduction?

Angulation Thresholds for Distal Radial and Ulnar Fracture Reduction

Surgical fixation is recommended for fractures with postreduction radial shortening >3 mm, dorsal tilt >10°, or intra-articular displacement or step-off >2 mm. 1

Adult Reduction Parameters

The American Academy of Orthopaedic Surgeons provides clear guidelines for when reduction is necessary in distal radius fractures:

• Dorsal tilt >10° requires reduction 1
• Radial shortening >3 mm requires reduction 1
• Intra-articular displacement or step-off >2 mm requires reduction 1

These parameters are critical as they directly impact functional outcomes. Operative fixation resulting in less than 2 mm of residual articular surface step-off is typically necessary to avoid long-term complications such as osteoarthritis 1.

Additional Indications for Surgical Management

Certain fracture characteristics strongly suggest the need for operative intervention:

• Presence of a coronally oriented fracture line
• Die-punch depression
• More than three articular fracture fragments 1

Pediatric Considerations

Children have significantly greater remodeling potential than adults:

• Coronal angulation in pediatric distal radius fractures remodels at approximately 2-2.6° per month 2
• Repeat manipulation is generally not indicated in skeletally immature patients with coronal angulation <24° 2
• Quality of initial reduction is a statistically significant risk factor for redisplacement in pediatric fractures 3

Imaging Considerations

Proper imaging is essential for accurate assessment:

• Standard 3-view radiographic examination (posteroanterior, lateral, and 45° semipronated oblique) is appropriate for initial imaging 1, 4
• Adding a fourth projection (semisupinated oblique) increases diagnostic yield for distal radius fractures 1
• CT without IV contrast can better visualize fracture morphology in complex cases 4

Treatment Algorithm

1. Initial Assessment:

   • Obtain standard 3-view radiographs
   • Measure angulation, shortening, and articular step-off

2. Decision for Reduction:

   • Adults: Reduce if dorsal tilt >10°, radial shortening >3 mm, or intra-articular displacement >2 mm
   • Children: Consider greater tolerance for angulation due to remodeling potential

3. Post-Reduction Management:

   • If stable after reduction: Consider casting for definitive treatment
   • If unstable or meets surgical criteria: Consider operative fixation
   • Monitor for complications such as median nerve injury 5

Common Pitfalls to Avoid

• Inadequate imaging: Always obtain multiple views to properly visualize the fracture 4
• Underestimating articular involvement: Intra-articular step-off >2 mm leads to osteoarthritis if not properly reduced 1
• Overlooking associated injuries: Be vigilant for median nerve injuries, which can complicate distal radius fractures 5
• Excessive immobilization: Can lead to chronic pain, joint stiffness, and muscle atrophy 4
• Inadequate immobilization: Results in delayed healing, malunion, and progressive displacement 4

By following these guidelines, clinicians can make appropriate decisions regarding the need for reduction in distal radial and ulnar fractures, optimizing both short-term recovery and long-term functional outcomes.