The Diagnostic Challenges of the Digitation Sign for Subscapularis Tears: Impact of Observer Expertise

To investigate preoperative systematic magnetic resonance imaging (MRI) evaluation of subscapularis (SSC) lesions using the digitation sign by medical practitioners with various levels of experience.

A retrospective analysis was conducted on patients who underwent arthroscopy-assisted rotator cuff repair between April 2023 and September 2024. The inclusion criteria required preoperative 1.5 Tesla MRI scans with standardized protocols within 2 months of surgery. Patients were divided into SSC tears and intact groups based on intraoperative arthroscopic findings. Preoperative MRI images were independently evaluated by medical students, residents, orthopedic fellows, and attending doctors, blinded to arthroscopic findings. The sensitivity and specificity of SSC tear detection were analyzed for each group. Arthroscopic findings were assessed in real time by the single surgeon and documented in the operative reports.

Out of 152 patients, 73 (48.0%) had arthroscopically confirmed SSC tears. Sensitivities for detecting SSC tears via the digitation sign were 57.5%, 72.6%, 80.8%, and 82.1%, respectively. There was a statistically significant difference in medical students (57.5%) and residents (72.6%) (P = .035). The specificity was low across all groups (54.4%, 63.3%, 32.9%, and 50.0% for medical students, residents, fellows, and attending doctors). Higher training levels correlated with improved sensitivity but worsened specificity, suggesting overdiagnosis by more experienced practitioners.

The digitation sign is a valuable tool for SSC tear detection but has limitations. These findings highlight the need for enhanced observer training and a cautious approach to interpreting the digitation sign in isolation. Combining multiple imaging findings and contextual clinical information is essential for reducing diagnostic errors and improving patient outcomes.

Level III, retrospective case-control study.