What are the implications of an impacted ulnar styloid fracture?

Implications of an Impacted Ulnar Styloid Fracture

An impacted ulnar styloid fracture, when occurring with a distal radius fracture, generally does not require surgical fixation and has minimal impact on functional outcomes when the distal radioulnar joint (DRUJ) remains stable after radius fixation.

Key Clinical Implications

Functional Outcomes and Prognosis

• Ulnar styloid fractures occur in approximately 40-65% of all distal radius fractures, making them a common concomitant injury 1.

• The presence of an ulnar styloid fracture does not significantly affect patient-rated outcomes when the DRUJ is stable after distal radius fixation, as demonstrated by multiple prospective studies showing no difference in DASH scores (6.7 vs 8.4, p=0.47) or PRWE scores (4.8 vs 7.5, p=0.24) at 12 months 2.

• Neither the size, displacement, nor healing status of the ulnar styloid fracture affects functional outcomes in patients with stable DRUJ after distal radius fixation 3.

Union and Healing Considerations

• Approximately 75% of ulnar styloid fractures remain nonunited at one year, yet this nonunion status does not correlate with worse functional outcomes or increased pain when the DRUJ is stable 2.

• Nonunion rates are higher in conservatively treated cases, but this does not translate to clinically significant differences in pain or function between surgically and conservatively treated groups 4.

Treatment Decision Algorithm

Step 1: Assess DRUJ Stability

• Obtain a true lateral radiograph of the carpus to assess DRUJ alignment after distal radius fixation 5.
• Perform clinical ballottement testing after radius fixation to evaluate DRUJ stability 1.

Step 2: Treatment Based on Stability

• If DRUJ is stable: No fixation of the ulnar styloid is indicated, regardless of fracture location (tip vs base), displacement, or impaction 2, 3.
• If DRUJ remains unstable after radius fixation: Consider selective surgical fixation of base fractures, particularly those with significant displacement 1.

Step 3: Immobilization Strategy

• Use rigid immobilization rather than removable splints for displaced distal radius fractures 6.
• Delayed casting within a few days does not negatively impact outcomes for stable fractures 6.

Important Caveats and Pitfalls

When to Consider Surgical Fixation

• Surgery may be indicated only in selective cases with persistent DRUJ instability during ballottement testing after radius fixation 1.

• Base fractures have higher incidence of TFCC tears and DRUJ instability compared to tip fractures, but this alone does not mandate fixation 4.

Complications of Surgical Treatment

• Operative treatment carries significantly higher complication rates (OR 14.3,95% CI 1.08-188) compared to conservative management 1.

• Better wrist function at 6 months is observed in non-surgically treated patients (SMD 0.57,95% CI 0.30-0.90), though this difference disappears by 12 months 1.

Rehabilitation Considerations

• Begin active finger motion exercises immediately upon diagnosis to prevent stiffness, which is one of the most functionally disabling complications 5.

• Early wrist motion is not routinely necessary following stable fracture fixation 5.

• Obtain radiographic follow-up at approximately 3 weeks and at the time of immobilization removal 6.

Long-term Monitoring

• Reevaluate all patients with unremitting pain during follow-up, as this may indicate complications requiring intervention 5.

• The American Academy of Orthopaedic Surgeons guidelines are inconclusive regarding routine fixation of ulnar styloid fractures associated with distal radius fractures 5, 6.