From the Guidelines
Negative ulnar variance is a condition where the ulna is shorter than the radius at the wrist joint, which can be diagnosed through radiographs, specifically by measuring ulnar variance on posterior-anterior and lateral views 1. This condition refers to a situation where the distal end of the ulna does not extend as far as the distal end of the radius, creating a relative shortening. The diagnosis of negative ulnar variance is typically made through imaging, with radiographs being the initial step in evaluating chronic wrist pain 1. Some key points to consider about negative ulnar variance include:
- It can be congenital or acquired through various means such as trauma or previous surgeries
- It may cause less pressure on the ulnar side of the wrist, potentially protecting against certain conditions like ulnar impaction syndrome
- However, it can also lead to issues like instability of the distal radioulnar joint or increased stress on the radial side of the wrist
- Many individuals with negative ulnar variance are asymptomatic, and the condition may be discovered incidentally during imaging for other reasons
- Treatment is generally reserved for cases where the variance is causing pain or functional limitations. The standard radiographic examination for assessing ulnar variance, as outlined in the ACR Appropriateness Criteria for chronic wrist pain 1, consists of posterior-anterior and lateral views, which are crucial for demonstrating malalignments and measuring ulnar variance accurately.
From the Research
Definition of Negative Ulnar Variance
- Negative ulnar variance is a condition where the ulna is relatively shorter than the radius at the carpus 2.
- This condition can be found in a significant percentage of normal wrists, with one study reporting an incidence of 21% in 203 normal wrists 2.
Association with Wrist Pathology
- Negative ulnar variance has been associated with various wrist pathologies, including carpal ligamentous instabilities, such as dorsiflexion instability, palmar flexion instability, scapholunate dissociation, and lunate and perilunate dislocations 2.
- However, other studies have found that a long ulna (positive ulnar variance) is more commonly associated with harmful effects on the ulnar compartment of the wrist, including degeneration and perforation of the triangular fibrocartilage complex (TFCC) and cartilaginous wear of the carpal bones (ulnar impaction syndrome) 3.
Prognostic Value
- Negative ulnar variance has been found to have prognostic value in the progression of Kienböck's disease, with a significant difference in ulnar variance seen between early and late stages of the disease 4.
- The presence of negative ulnar variance may encourage further progression of the collapse of the lunate, while neutral or positive ulnar variance seems to protect the lunate against deformation 4.