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