PRE-OPERATIVE MRI IMAGING ACCURATELY DETECTS THE ARTHROSCOPIC COMMA SIGN IN SUBSCAPULARIS TEARS

Abstract Purpose The purpose of this study was to assess the accuracy and reliability of routine preoperative MR imaging in the detection of the comma sign, compared against the gold standard of arthroscopic findings. Methods and Materials Preoperative MRI exams in consecutive patients undergoing arthroscopic subscapularis tendon repair, over a 5 year timeframe, were retrospectively reviewed for: full thickness tears subscapularis (SC) and supraspinatus (SS) tendons, fatty atrophy SC and SS muscles, and status of the long head of biceps tendon (LHB). Each case was also evaluated for presence or absence of a comma sign on MRI. Surgical findings served as the diagnostic standard of reference in determination of a comma sign. Results Study cohort included 45 male, 10 female patients (mean age 56, range 32-80 yrs). Comma sign was present at arthroscopy in 19 patients (34.5%). Interclass and intra-rater correlation showed 100% agreement in pre-operative assessment of a comma sign on MRI. MRI showed an overall accuracy of 83.6% in diagnosis of a comma sign, (sensitivity 63.2%, specificity 94.4%, positive predictive value 85.7%, negative predictive value 82.9%, positive likelihood ratio 11.37 and negative likelihood ratio 0.39). No statistically significant association observed between an arthroscopic comma sign and patient demographics, or MRI findings of full thickness rotator cuff tears, muscle fatty atrophy or LHB pathology. Conclusions MR imaging illustrates excellent reliability, and good specificity and accuracy in detection of the arthroscopic comma sign in the setting of subscapularis tendon tearing. Detection of a comma sign on MRI, may be important preoperative planning information in the arthroscopic management of patients with subscapularis tendon tears.