Subscapularis Tendon Slip Number and Coracoid Overlap Are More Related Parameters for Subcoracoid Impingement in Subscapularis Tears: A Magnetic Resonance Imaging Comparison Study.

PURPOSE: To investigate the effects of the subscapularis tendon slip number (STSN) and coracoid morphology by magnetic resonance imaging in patients with and without subscapularis tears.

METHODS: Patients who underwent shoulder arthroscopy between February 2004 and June 2015 were re-evaluated. Those with a subscapularis tear (study group) and those with other pathologies (control group) were compared with each other. Magnetic resonance imaging scans and surgery videos of the patients were reassessed. Transverse and sagittal coracohumeral distance (CHD), coracoid overlap (CO), coraco-coracoid base angle (CBA), coracoglenoid distance (CGD), and STSN were measured.

RESULTS: The study and control groups comprised 141 and 78 patients, respectively. The mean age was 57.01 ± 10.95 (similar in both the groups). The mean transverse CHD and sagittal CHD were not different between the groups and also between female and male patients. For the study and control groups, the mean CBA and CGD values were also similar. The mean CO was 24.01 ± 4.9 and 21.29 ± 4.58 for the study and control groups, respectively (P < .001). With the receiver operating characteristic curve of the CO, the sensitivity was 62% and the specificity was 64% at the cutoff value of 22.85 mm. The STSN was in the range between 1 and 6; the STSN was 3 or less in 61.5% of the study group and in 38.5% of the control group (P = .005).

CONCLUSIONS: The CO was the most valuable parameter predicting any potential subcoracoid impingement, and the STSN was inversely correlated with subscapularis tears. However, in predicting a potential subcoracoid impingement, the CHD measurements were not significant, as well the CGD and CBA.

LEVEL OF EVIDENCE: Level III, retrospective comparative study.