What are the implications of a 6 mm negative ulnar variance?

From the Guidelines

Negative ulnar variance of 6 mm is a significant anatomical variation that requires proper evaluation and management to prevent long-term morbidity and mortality, and to improve quality of life. This condition can lead to increased pressure on the radial side of the wrist and may be associated with conditions like Kienböck's disease (avascular necrosis of the lunate bone) or TFCC (triangular fibrocartilage complex) tears, as suggested by the American College of Radiology guidelines for chronic wrist pain 1.

Key Considerations

• Normal ulnar variance ranges from +2 mm to -2 mm, and a variance of -6 mm is considered significant.
• Patients with this finding may experience wrist pain, decreased grip strength, or limited range of motion.
• Management depends on symptom severity and may include conservative measures like wrist splinting, anti-inflammatory medications, and activity modification for mild cases.
• For persistent symptoms, surgical interventions such as ulnar lengthening procedures or radial shortening osteotomy might be considered to correct the variance and redistribute forces across the wrist, as evaluated by MRI for TFCC lesions 1.

Diagnostic Approach

• Radiographs, including posterior-anterior and lateral views, are necessary for accurate measurement of ulnar variance 1.
• MRI is highly accurate for lesions involving the radial (central) zone of the disc, especially with the use of high-resolution fast spin-echo or 3-D gradient-recalled pulse sequences 1.

Treatment Approach

• Proper evaluation by a hand specialist is recommended to determine the appropriate treatment approach based on individual symptoms and functional limitations.
• Conservative measures and surgical interventions should be considered to improve quality of life and prevent long-term morbidity and mortality.

From the Research

Ulnar Variance and Associated Conditions

• A 6 mm negative ulnar variance refers to a condition where the ulna is shorter than the radius by 6 mm.
• According to 2, negative ulnar variance has been associated with Kienböck's disease, avascular necrosis of the scaphoid, and scapholunate dissociations, although this could not be confirmed in the study.

Treatment Options for Ulnar Wrist Pain

• Ulnar shortening osteotomy is a surgical procedure that can be used to treat ulnar wrist pain, particularly in cases with positive ulnar variance 3, 4, 5, 6.
• The goal of ulnar shortening osteotomy is to level the distal radioulnar joint and relieve pressure on the ulnar compartment of the wrist 4.
• Studies have shown that ulnar shortening osteotomy can be an effective treatment for ulnar wrist pain, with improvements in symptoms and functional outcomes 4, 5, 6.

Considerations for Ulnar Shortening Osteotomy

• The procedure can be performed using various techniques, including open and arthroscopic surgery 3, 4.
• The choice of technique and the amount of ulnar shortening required will depend on the individual patient's condition and the surgeon's preference 3, 4.
• Potential complications of ulnar shortening osteotomy include nonunion, infection, and ulnar carpal subluxation 5, 6.