Ulnar Bowing and Distal Radioulnar Joint Anatomy: A Three-Dimensional, In Situ Clinical Assessment

Area of Science:

• Orthopedic surgery
• Radiology
• Anatomy

Background:

• Distal radioulnar joint (DRUJ) injuries present management challenges.
• The ulna's multiplanar curvature complicates DRUJ assessment with 2D imaging.
• Accurate anatomical assessment is crucial for effective treatment of forearm trauma.

Purpose of the Study:

• To establish normal anatomical ranges for ulnar bowing, DRUJ ulnar variance (UV), and sigmoid notch angle.
• To assess the relationship between ulnar bowing and DRUJ UV using 3D CT angiography.
• To improve the treatment of forearm traumas and DRUJ pathologies through enhanced anatomical understanding.

Main Methods:

• Utilized full-length, 3D computed tomography angiography scans of 82 intact upper extremities.
• Reconstructed scans into 3D models for detailed analysis.
• Characterized ulnar bowing and DRUJ metrics using computer-aided design software and statistical analysis.

Main Results:

• Identified specific locations, depths, and angles for proximal and distal ulnar bows.
• Found significant positive correlations between proximal ulnar bow angle and UV, and negative correlations for the distal ulnar bow angle.
• Demonstrated a strong negative correlation between DRUJ UV and sigmoid notch angle in the coronal plane.

Conclusions:

• Sagittal alignment and translation at the DRUJ are directly related to distal ulna bowing.
• A detailed 3D understanding of these anatomical relationships enhances preoperative planning for ulnar-side pathology.
• This study provides critical normative data for improved clinical management of DRUJ issues.