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D'Arcy Little MD CCFP FCFP FRCPC,

D’Arcy Little, MD, CCFP, FCFP, FRCPC, Medical Director, Journal of Current Clinical Care and www.healthplexus.net, Radiologist, Orillia Soldiers’ Memorial Hospital, Adjunct Clinical Lecturer, Departments of Medical Imaging and Family Medicine, University of Toronto, Toronto, ON.

CLINICAL TOOLS

Abstract:
Ulnar variance disorders, encompassing both positive and negative variance conditions, represent important causes of wrist pain and dysfunction. Positive ulnar variance leads to ulnar impaction syndrome, while negative ulnar variance can cause ulnar impingement syndrome and predispose to conditions like Kienböck disease. These distinct entities present unique diagnostic challenges and require tailored management approaches. This article reviews the current understanding of both positive and negative ulnar variance conditions, focusing on diagnostic approaches and evidence-based treatment strategies.

Key Words: ulnar negative variance, ulnar impingement, diagnosis, management.
Diagnostic Distinction is Critical: Negative ulnar variance (ulna shortened >2.5mm compared to radius) and ulnar impingement syndrome (radioulnar abutment) are related but distinct conditions requiring different evaluation approaches. Proper radiographic positioning with shoulder abducted 90° and elbow flexed 90° is essential for accurate measurement.
Strong Association with Carpal Instability: There’s a significant 49% incidence of negative ulnar variance in patients with carpal ligamentous instabilities, making it an important indicator for careful evaluation of carpal stability and associated conditions like Kienböck disease.
Treatment Algorithm Should Guide Surgical Selection: For ulnar shortening requirements ≥3mm, ulnar shortening osteotomy (USO) is preferred, while arthroscopic wafer procedure (AWP) is suitable for lesser degrees. AWP offers faster return to work (57.7 vs 117 days) and fewer complications compared to USO.
Conservative Management Often Fails: When conservative treatment (immobilization, anti-inflammatory medications) fails to provide adequate symptom relief, surgical intervention becomes necessary, with both USO and AWP showing good outcomes (73-94% good/excellent results).
Positioning Matters for Diagnosis: Ulnar variance measurements can be falsely reduced in supination and exaggerated in pronation or with fist clenching. Always ensure neutral wrist positioning during radiographic assessment to avoid misdiagnosis.
MRI Timing is Key: 3T MRI offers superior signal-to-noise ratio compared to 1.5T and allows earlier, more confident detection of characteristic focal signal changes in the ulnar part of the lunate, which often normalize after successful ulnar recession surgery.
Hardware Removal is Common: In USO procedures, expect a 36.7% rate of hardware irritation requiring implant removal at an average of 8.6 months post-surgery. Counsel patients about this likelihood during pre-operative discussions to manage expectations appropriately.
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Related Terms: Radiology, ulnar negative variance, ulnar impingement, diagnosis, management
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