🔍 Key Findings

• Dogs with MCD demonstrated significant radioulnar joint malformation in the central, centrolateral, and lateral compartments on transverse CT imaging.
• Radioulnar ratios were significantly decreased at measurement points 3–5 in MCD elbows (p = 0.044), indicating widening and incongruity of the radioulnar joint space.
• Medial and mediocentral radioulnar compartments remained congruent, showing no significant differences between MCD and control elbows.
• Radioulnar opening angle did not differ between groups, suggesting that joint malformation was localized rather than reflected by global angular changes.
• No evidence of radioulnar step formation was identified, despite previous theories linking step incongruity to MCD development.
• Gender, breed, and body weight were not associated with radioulnar ratios, suggesting morphology rather than demographic factors influenced findings.
• Central and lateral radioulnar pathology may be missed during routine medial elbow arthroscopy, potentially contributing to persistent clinical signs after treatment.
• Radioulnar malformation may contribute both to MCD pathogenesis and to incomplete success following arthroscopic treatment.