Biomechanical analysis of anterior capsule reconstruction and latissimus dorsi transfer for irreparable subscapularis tears

Abstract

Background: Anterior capsule reconstruction (ACR) and latissimus dorsi transfers (LTs) have been proposed as solutions for irreparable subscapularis tears. The purpose of this study was to biomechanically assess the effects of ACR and LT separately and together for treatment of irreparable subscapularis tears. Materials and method: Eight cadaveric shoulders underwent 5 testing conditions: (1) intact, (2) irreparable subscapularis tear, (3) ACR, (4) ACR+LT, and (5) LT alone. Anteroinferior translation loads of 20, 30, and 40 N were applied. Range of motion and magnitudes of glenohumeral anterior and inferior translation at 0°, 30°, and 60° of abduction and at 30° and 60° of external rotation were measured for each testing condition. Results: At 30° of abduction and 60° of external rotation, ACR and ACR+LT restored anterior and inferior translation to intact (P > .702) for 30 and 40 N of anteroinferiorly directed force. LT alone did not restore anteroinferior stability at 30 N of distraction force at 30° of glenohumeral abduction and 60° of external rotation (P < .001). However, ACR and ACR+LT led to significant decreases in total range of motion compared to intact at 0° and 30° of abduction (P < .007). Conclusions: ACR with dermal allograft was able to restore anteroinferior stability in the setting of irreparable subscapularis tears but resulted in decreased total range of motion. LT alone was less effective than ACR in restoring glenohumeral stability. The addition of LT as a dynamic restraint did not increase the efficacy of ACR.