Treatment of Distal Ulnar Fractures
For isolated distal ulnar fractures that are stable and minimally displaced, immobilization with a removable splint or short-arm cast for 2-3 weeks is the recommended treatment, while unstable or significantly displaced fractures require surgical fixation. 1, 2
Initial Assessment and Classification
When evaluating a distal ulnar fracture, determine:
- Stability of the fracture – assess for displacement, angulation, and associated distal radius fracture 2
- Degree of displacement – fractures with >3mm displacement or >10° angulation are considered significantly displaced 3
- Intra-articular involvement – these fractures may require surgical intervention to prevent post-traumatic arthritis 4
- Associated injuries – most distal ulnar fractures occur with concomitant distal radius fractures 1, 2
Treatment Algorithm
For Stable, Minimally Displaced Fractures:
- Cast immobilization is the preferred initial treatment for stable distal ulnar fractures 2
- A sugar-tong splint followed by short-arm cast for a minimum of 3 weeks is appropriate 1
- Removable splints are an acceptable alternative for minimally displaced fractures 3
- Initiate active finger motion exercises immediately to prevent stiffness, which is one of the most functionally disabling complications 3
For Unstable or Displaced Fractures:
- Operative fixation should be considered when there is malalignment or instability 2
- Intramedullary stabilization with headless compression screws allows minimal incision and promotes union in approximately 6.5 weeks 5
- Plate osteosynthesis or Kirschner wire pinning are alternative surgical options 5
- Intra-articular fractures with displacement require surgical reduction to prevent joint incongruity and arthritis 4
Special Consideration: Ulnar Styloid Fractures
Ulnar styloid fractures associated with distal radius fractures typically do not require fixation 6, 2. Key points:
- More than half of distal radius fractures include an ulnar styloid fracture 2
- Ulnar styloid nonunion usually does not cause clinical problems 2
- Neither initial displacement nor size of ulnar styloid fracture affects clinical outcome when the radius is adequately treated 2
- The AAOS guideline states there is insufficient evidence to recommend for or against fixation of ulnar styloid fractures 6
Post-Treatment Management
- Radiographic follow-up at approximately 3 weeks and at time of immobilization removal to confirm healing 3
- For surgical cases, maintain short-arm splint for less than 2 weeks post-operatively 5
- Continue active finger motion throughout treatment to prevent stiffness 3
- Monitor for complications including skin irritation and muscle atrophy, which occur in approximately 14.7% of immobilization cases 3
Common Pitfalls to Avoid
- Do not overlook associated distal radius fractures – isolated distal ulnar fractures are rare 7
- Avoid prolonged immobilization – this increases risk of stiffness without improving outcomes 6
- Do not routinely fix ulnar styloid fractures – they rarely cause functional problems even with nonunion 2
- Hardware prominence is common with surgical fixation due to thin soft tissue coverage and may necessitate implant removal 7