Clinical Report: Ulnar Styloid Abduction Angle as an Innovative Radiological Indicator
Overview
This study identifies the ulnar styloid abduction angle (USAA) as a predictor of Palmer Type IB TFCC tears. A USAA of ≥17.5° demonstrates high sensitivity and specificity for identifying these injuries.
Background
Injuries to the triangular fibrocartilage complex (TFCC) are a common cause of ulnar-sided wrist pain and can lead to significant functional impairment. Understanding the anatomical factors associated with TFCC tears is crucial for early diagnosis and intervention, particularly in high-risk populations.
Data Highlights
Measurement
Case Group (TFCC Tears)
Control Group (Intact TFCC)
USAA
21.0° ± 4.0°
14.8° ± 3.8°
Key Findings
The USAA was significantly greater in the case group than in the control group (p < 0.001).
Increased USAA was independently associated with Palmer Type IB tears (aOR = 1.37 per degree; p < 0.001).
A non-linear threshold effect was observed; risk of rupture increased steeply when USAA exceeded 17.5°.
The optimal cut-off value of ≥17.5° yielded a sensitivity of 81.8% and a specificity of 78.2% for identifying tears.
The area under the receiver operating characteristic curve (AUC) was 0.849 after optimism correction.
Clinical Implications
The USAA can be reliably measured on standard wrist radiographs.
Conclusion
The USAA serves as a predictor for Palmer Type IB TFCC tears.
