Updated: 4/10/2017

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
Introduction
  • Definition
    • length of the ulna compared to the radius
    • measured in shoulder abducted 90deg, elbow flexed 90deg, forearm neutral, hand aligned with forearm axis
  • 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
  • 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
 Ulnar Variance
Ulnar Variance Length Difference (ulnar - radial length) Load Passing Through Radius Load Passing Through Ulna Images
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)

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(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? Review Topic

QID: 1153
1

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

1%

(30/2444)

2

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

26%

(646/2444)

3

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

2%

(61/2444)

4

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

65%

(1593/2444)

5

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

4%

(101/2444)

L 3

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