Updated: 5/20/2021

Ulnar Variance

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https://upload.orthobullets.com/topic/6046/images/Negative ulnar variance_moved.jpg
https://upload.orthobullets.com/topic/6046/images/neutral.jpg
https://upload.orthobullets.com/topic/6046/images/positive.jpg
https://upload.orthobullets.com/topic/6046/images/negative.jpg
  • Summary
    • Ulnar Variance is the length of the ulna compared to the length of the radius at the wrist.
    • Diagnosis is made radiographically with PA wrist radiographs. Positive ulnar variance indicates a longer ulna compared to the radius and a negative ulnar variance indicates a shorter ulna. 
    • Treatment depends on severity of symptoms and underlying condition.
  • Epidemiology
    • Demographic
      • male:female relationship
        • UV is lower in males than females
      • age bracket
        • UV increases with age
    • Risk factors
      • positive UV may be present in child gymnasts
        • distal radial growth plate injury leading to premature closure of distal radial physis
  • Etiology
    • Pathophysiology
      • congenital
        • Madelung deformity (positive UV)
        • reverse Madelung deformity (negative UV)
      • trauma/mechanical
        • distal radius/ulnar fracture with shortening
        • growth arrest (previous Salter-Harris fracture)
        • DRUJ injuries (Galeazzi and Essex-Lopresti)
      • iatrogenic
        • joint leveling procedures (radial or ulnar shortening/lengthening)
        • radial head resection (positive UV)
    • Associated conditions
      • positive ulnar variance
        • ulnar abutment syndrome
        • SLD
        • TFCC tears
        • arthrosis
          • ulnar head
          • lunate
          • triquetrum
        • lunotriquetral ligament tears
      • negative ulnar variance
        • Kienbock's disease
        • ulnar impingement syndrome
          • ulna impinges on the radius proximal to the sigmoid notch
  • Classification
    • Ulnar Variance
      Ulnar Variance
      Length Difference 
      (ulnar - radial length)
      Load Passing Through Radius
      Load Passing Through Ulna
      Positive
      +2mm
      60%
      40%
      Positive
      +1mm
      70%
      30%
      Neutral
      0 (< 1mm)
      80%
      20%
      Negative
      -1mm
      90%
      10%
      Negative
      -2mm
      95%
      5%
  • Anatomy
    • Neutral ulnar variance (ulnar zero)
      • difference between ulnar and radial length is <1mm
    • Positive ulnar variance
      • ulnar sided wrist pain from increased impact stress on the lunate and triquetrum
      • UV becomes more positive in pronation
      • UV becomes more positive during grip
    • Negative ulnar variance
      • UV decreases in supination
  • Imaging
    • Radiographs
      • recommended view
        • PA of the wrist with shoulder abducted 90 deg, elbow flexed 90 deg, neutral forearm rotation
    • Method to determine ulnar variance
      • draw 2 lines
        • 1 line tangential to the articular surface of the ulna and perpendicular to its shaft
        • 1 line tangential to the lunate fossa of the radius and perpendicular to its shaft.
      • measure the distance between these 2 lines (normal is 0mm)
      • if the ulnar tangent is distal to the radial tangent = positive UV
      • if the ulnar tangent is proximal to the radial tangent = negative UV
    • MRI
      • can estimate but not quantify degree of UV
      • because specific wrist position cannot be duplicated in MRI
  • Treatment
    • Depends on specific condition
      • ulnar abutment syndrome
      • TFCC tears
      • Kienbock's disease
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Questions (1)

(OBQ05.267) In a patient with -2.5mm of ulnar variance, which of the following statements best describes the distribution of compressive load across the wrist?

QID: 1153
1

Approximately 50% of the wrist load is accepted by distal radius and 50% is accepted by the distal ulna

1%

(33/2964)

2

Approximately 80% of the wrist load is accepted by the distal radius and 20% is accepted by the distal ulna

27%

(814/2964)

3

Approximately 80% of the wrist load is accepted by the distal ulna and 20% is accepted by the distal radius

2%

(73/2964)

4

Approximately 95% of the wrist load is accepted by the distal radius and 5% is accepted by the distal ulna

64%

(1904/2964)

5

Approximately 60% of the wrist load is accepted by the distal radius and 40% is accepted by the distal ulna

4%

(125/2964)

L 3 C

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