Comparison of Clinical Examination, Ultrasonography, and Magnetic Resonance Imaging in the Diagnosis of Arthroscopically Confirmed Partial Subscapularis Tears

Abstract

Background: Partial-thickness subscapularis (SSC) tears are frequently underdiagnosed due to subtle clinical presentation and the limited sensitivity of routine imaging modalities, particularly magnetic resonance imaging (MRI). Dynamic ultrasonography (USG) and structured test combinations may improve early detection. Purpose/Hypothesis: The purpose of this study is to compare the diagnostic accuracy of individual SSC-specific clinical tests, systematic 3-test combinations, USG, and MRI in detecting partial-thickness SSC tears, using arthroscopy as the reference standard. It was hypothesized that structured 3-test combinations and dynamic USG would outperform MRI in detecting partial SSC tears. Study Design: Cohort Study (diagnosis); Level of evidence, 2. Methods: A total of 46 patients undergoing arthroscopy for rotator cuff pathology were prospectively assessed using 6 SSC-specific clinical tests, dynamic USG, and standardized MRI sequences. Two independent, blinded observers evaluated all diagnostic modalities. All clinically relevant 3-test combinations were systematically analyzed and considered positive when >= 2 tests were positive. Diagnostic performance metrics-including sensitivity, specificity, accuracy, area under the curve (AUC), and interobserver agreement-were compared with arthroscopic findings. Results: The triads of Bear Hug + Napoleon + internal rotation lag sign and Bear Hug + Belly Press + Napoleon demonstrated the highest clinical diagnostic accuracy (sensitivity, 83.9% [95% CI, 67.4-92.9]; specificity, 100% [95% CI, 79.6-100.0]; AUC, 0.92 [95% CI, 0.85-0.98]). USG outperformed MRI across all diagnostic metrics (sensitivity, <= 96.8% [95% CI, 83.8-99.4]; AUC, 0.92 [95% CI, 0.83-1.00]), whereas MRI showed limited sensitivity (ranging from 61.3% [95% CI, 43.8-76.3] to 67.7% [95% CI, 50.1-81.4]). Interobserver agreement was almost perfect for MRI (kappa approximate to 0.91) and substantial for USG (kappa approximate to 0.68). Diagnostic accuracy was higher for Lafosse type 2 tears, although USG and the top-performing clinical triad remained effective across both tear subtypes. Conclusion: Dynamic USG and structured SSC-specific clinical test combinations offer superior diagnostic accuracy compared with MRI for partial SSC tears.