The Invisible MGHL Test: Diagnostic Value and Benefits for the Repair of Retracted Subscapularis Tears

Abstract

Background: Some full-thickness subscapularis tendon tears and partial tears of the deep layer are difficult to characterize, leading to misdiagnosis. Purpose: To evaluate the association between displacement of the middle glenohumeral ligament (MGHL) and retracted tears of the subscapularis tendon as a possible test to improve diagnosis. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Videos (N = 100) recorded during arthroscopic rotator cuff repair involving a torn subscapularis tendon were analyzed retrospectively to assess the association between the MGHL test (nonvisibility of the MGHL) and other objective anatomic criteria. The invisible MGHL test was defined as positive if the MGHL was initially nonvisible in the beach-chair position and appeared only when the subscapularis tendon was pulled back into position by using a 30° arthroscope from the standard posterior portal. The parameters considered during the initial exploration were (1) visibility of the horizontal part of the subscapularis tendon; (2) visibility of the MGHL in its usual position, crossing the superior border of the subscapularis tendon; (3) exposure of the lateral border of the subscapularis tendon (full-thickness retracted tear); and (4) complete or partial exposure of the lesser tuberosity of the humerus. Tendon retraction was evaluated in 3 stages according to the Patte classification. Results: The invisible MGHL test result was positive in 45% of cases. It was positive in 6% of cases (2 of 31) when there was no subscapularis tendon retraction and in 62% of cases (43 of 69) when there was partial or complete retraction ( P < .001). The invisible MGHL test was significantly associated with the width of the tear ( P < .001) and exposure of the lateral border of the subscapularis tendon (full-thickness retracted tear, P = .0002). After repair, the MGHL was visible in its anatomic position in 96% of cases. Conclusion: A positive invisible MGHL test is an alternative indication of subscapularis tendon retraction, and the relocation of the MGHL can also be used after repair to assess the proper anatomic repositioning of the subscapularis tendon.