Subscapularis (SSC) tendon tears: diagnostic performance and reliability of magnetic resonance arthrography (MRA)...

To evaluate the diagnostic performance and reliability of magnetic resonance of arthrography (MRA) in diagnosis of subscapularis (SSC) tendon tears between two reviewers with varying levels of experience, and compare the results with clinical tests.

SSC tendons were retrospectively evaluated in a total of 272 patients with arthroscopic confirmations. A total of 548 shoulder MRAs were evaluated by two musculoskeletal radiologists, and SSC tendon pathologies were classified into three groups: intact tendon (n = 149), partial-thickness tear (n = 92), or full-thickness tear (n = 31). Diagnostic performance was determined using arthroscopy as gold standard and compared with results of four clinical tests. Intra- and inter-observer reliabilities of two reviewers were evaluated using kappa statistics.

For full-thickness tears, mean values of sensitivity, specificity, and accuracy of reviewer 1/reviewer 2 were 71.0%/87.1%, 97.3%/98.3%, and 94.4%/95.5%, respectively. For partial-thickness tears, mean values of sensitivity, specificity, and accuracy were 72.8%/73.4%, 78.3%/81.2%, and 76.5%/78.5%, respectively. Intra- and inter-observer reliabilities for both reviewers were good to very good (k = 0.85/0.93, p < 0.001; k = 0.74-0.89, p < 0.001). For all clinical tests, while specificity was very high, sensitivity was very low and the overall accuracy was also low.

MRA showed high diagnostic performance for the diagnosis of SSC tendon tears, especially full-thickness tears, with good inter- and intra-observer reliabilities, regardless of the level of experience of the reviewer.