Sagging Peribursal Fat Sign as a Highly Specific Sonographic Finding to Diagnose Full‐Thickness Supraspinatus Tendon Tear

BACKGROUND: Full-thickness supraspinatus tendon tears can be difficult to diagnose when direct ultrasonographic signs are inconclusive. This study aimed to evaluate the diagnostic performance of the sagging peribursal fat sign (SPFS) in this diagnostically challenging population. METHODS: This retrospective diagnostic accuracy study included 104 patients who underwent shoulder ultrasonography to evaluate chronic shoulder pain and arthrosonography to assess a suspected supraspinatus tendon tear in the absence of definite ultrasonographic evidence of a full-thickness defect. Arthrosonographic leakage into the subacromial-subdeltoid bursa served as the reference standard. Diagnostic performance of the SPFS and four conventional indirect signs and inter-reader agreement were assessed. RESULTS: Forty-three patients had a positive leakage sign. The SPFS showed 88.4% sensitivity, 98.4% specificity, 97.4% positive predictive value, 92.3% negative predictive value, and 94.2% accuracy. Overall inter-reader agreement was fair (κ = 0.36), while agreement between the two more experienced readers was moderate (κ = 0.52). CONCLUSION: In chronic shoulder pain patients with inconclusive direct ultrasonographic findings, the SPFS was a highly specific adjunctive sign for detecting full-thickness supraspinatus tendon tears. Although inter-reader agreement between experienced readers was moderate, overall agreement was fair, suggesting that experience may be important for reliable SPFS recognition.