Ulnar variance: facts and fiction review article.

The relative length of the ulna compared to the radius, or ulnar variance, appears to be an important element in wrist pathology. The length is determined by age, genetic factors, load (i.e. gymnasts) and gross elbow pathology. The negative ulnar variance or short ulna has been associated with Kienböck's disease, avascular necrosis of the scaphoid and scapholunate dissociations. This could not be confirmed in our observations. On the contrary, a long ulna (positive ulnar variance) is harmful for the ulnar compartment of the wrist as it causes degeneration and perforation of the triangular fibrocartilage complex (TFCC) and cartilaginous wear of the carpal bones (ulnar impaction syndrome). The ulnar variance is also determinant for the morphology of the sigmoid notch of the radius. With wrist arthroscopy a more precise diagnosis of ulnar wrist pain has become possible.