MRI of the Stener lesion

Area of Science:

• Orthopedic Surgery
• Radiology
• Medical Imaging

Background:

• Stener lesions, involving displaced thumb ulnar collateral ligaments (UCL), are crucial injuries in thumb instability.
• Accurate diagnosis is essential for appropriate surgical management.
• Magnetic resonance imaging (MRI) is a common modality for evaluating soft tissue injuries.

Purpose of the Study:

• To evaluate the diagnostic utility of MRI, specifically 2D STIR and 3D GRASS sequences, in detecting surgically induced Stener lesions in a cadaveric model.
• To assess the sensitivity, specificity, and inter/intraobserver agreement of MRI for Stener lesion identification.

Main Methods:

• Six cadaver thumbs underwent surgical creation of UCL tears and subsequent displacement to simulate Stener lesions.
• MRI examinations using 2D STIR and 3D GRASS sequences were performed before and after UCL displacement.
• Four musculoskeletal radiologists independently evaluated the MR images in a blinded manner for the presence of Stener lesions, with re-evaluation after an interval.

Main Results:

• The sensitivity of 3D GRASS for Stener lesion detection ranged from 0.17 to 0.67, with specificity from 0.33 to 1.0.
• 2D STIR demonstrated very low sensitivity (0.00-0.17) and moderate specificity (0.53-0.83).
• Intraobserver agreement for 3D GRASS was variable (kappa 0.27-0.75), indicating inconsistent readings even by the same observer.

Conclusions:

• Two-dimensional (2D) imaging, particularly STIR sequences with 3 mm slice thickness, appears inadequate for evaluating Stener lesions due to limited resolution.
• The overall poor sensitivity and specificity of both GRASS and STIR sequences, coupled with suboptimal interobserver agreement, suggest that MRI may not be sufficiently accurate for diagnosing Stener lesions.