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 login to view 1 more bullet age bracket login to view 1 more bullet Risk factors positive UV may be present in child gymnasts login to view 1 more bullet Etiology Pathophysiology congenital login to view 2 more bullets trauma/mechanical login to view 3 more bullets iatrogenic login to view 2 more bullets Associated conditions positive ulnar variance login to view 8 more bullets negative ulnar variance login to view 3 more bullets 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 login to view 1 more bullet Method to determine ulnar variance draw 2 lines login to view 2 more bullets 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