The aim of this study is to understand the relation between long head of the biceps tendon (LHBT) subluxation and full-thickness tears of the subscapularis.

Magnetic resonance imaging (MRI) scans of 94 patients undergoing shoulder arthroscopy were evaluated preoperatively for the presence or absence of LHBT subluxation. Intraoperative pathology of the biceps and subscapularis tendons was recorded. The diagnostic accuracy of LHBT subluxation on preoperative MRI in determining full-thickness subscapularis tendon tears was calculated.

Of the 94 patients in this study, 26 were diagnosed with LHBT subluxation preoperatively. Of these 26 patients, 9 were confirmed to have full-thickness tears of the subscapularis tendon (Lafosse grade 2 or higher). Of the remaining 68 patients who did not appear to have LHBT subluxation preoperatively, 2 were confirmed to have full-thickness tears of the subscapularis tendon. Thus LHBT subluxation on MRI as a predictor for full-thickness subscapularis tears had a sensitivity of 82%, specificity of 80%, positive predictive value of 35%, and negative predictive value of 97%. LHBT subluxation was directly correlated with the severity of the subscapularis tendon tear (P < .001).

The diagnostic value of subluxation of the LHBT, as seen on an axial MRI scan, lies primarily in its negative predictive value. If the LHBT is not subluxated, it is unlikely that a full-thickness tear of the subscapularis tendon is present. Surgeons should be cautious about relying on biceps subluxation as a primary diagnostic tool in predicting subscapularis tears.

Level IV, study of diagnostic test.