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Updated: Aug 16 2023

Ulnar Styloid Impaction Syndrome

  • Summary
    • Ulnar Styloid Impaction Syndrome is a common cause of ulnar-sided wrist pain secondary to impaction between the ulnar styloid tip and the triquetrum.
    • Diagnosis is made by PA wrist radiographs which reveal positive ulnar variance with subchondral sclerosis of the ulnar styloid and/or triquetrum.
    • Treatment is a course of rest, NSAIDs and splinting. In refractory cases, operative ulnar shortening osteotomy is indicated.
  • Epidemiology
    • Incidence
      • common cause of ulnar-sided wrist pain
    • Demographics
      • more prevalent in Asians than Whites
        • more positive ulnar variance
  • Etiology
    • Pathophysiology
      • pathoanatomy
        • impaction between ulnar styloid tip and triquetrum that is seen in patients with excessively long ulnar styloids or ulna positive wrists
    • Associated conditions
      • radial malunion
      • congenitally short radius
      • premature radial physeal closure
  • Anatomy
    • Ulnocarpal joint
      • transmits about 20% of the load through the wrist
        • increasing ulnar length by 2.5mm relative to the radius increases this load up to 50%
        • pronation and hand grasp both increase elative ulnar variance and transmission forces across the wrist
  • Classification
      • Ulnar Variance
      • Ulnar Variance
      • Length Difference
        (ulnar - radial length)
      • Load Passing Through Radius
      • Load Passing Through Ulna
      • Neutral
      • 0 (<1mm)
      • 80%
      • 20%
      • Positive
      • +2.5mm
      • 60%
      • 40%
      • -2.5mm
      • 95%
      • 5%
  • Presentation
    • Symptoms
      • ulnar side wrist pain
      • pain with pronation or grip
    • Physical exam
      • inspection
        • pain and swelling
        • tenderness along ulnar styloid and/or triangular fibrocartilage complex (TFCC)
      • motion
        • limited range of motion due to pain
      • ulnar stress test
        • maximum ulnar deviation, axial loading, rotation from supination to pronation to reproduce symptoms
  • Imaging
    • Radiographs
      • posteroanterior (PA) view to determine ulnar variance
        • excessive length determined by subtracting ulnar variance from ulnar styloid length and dividing this by the width of the ulnar head (<.22 is normal)
        • may exhibit subchondral sclerosis, cyst formation on ulnar side
      • pronated grip PA view
        • evaluate for any dynamic ulnar variance
      • contralateral comparison views
    • MRI
      • can help evaluate TFCC and the lunotriquetral interossesous ligament (LTIL)
  • Differential
    • TFCC injury
    • Ulnocarpal abutment syndrome
    • DRUJ injury
    • Pisotriquetral arthritis
    • ECU tendonitis
    • LT tear
  • Treatment
    • Nonoperative
      • activity modifications, NSAIDS, steroid injections
        • indications
          • first line of treatment
        • technique
          • rest should be tried for a minimum of 6-12 weeks
    • Operative
      • ulnar shortening osteotomy
        • currently, the gold standard
      • partial ulnar styloidectomy (Wafer procedure)
        • can be done open or arthroscopically
          • encouraging early results, but no superiority established
  • Complications
    • Tendon rupture
    • Persistent pain/hardware irritation
    • Infection
  • Prognosis
    • Little known about natural history
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