Abstract
BACKGROUND: Reverse total shoulder arthroplasty (rTSA) with the modified L'Episcopo procedure is useful for rotator cuff tear arthropathy with combined loss of elevation and external rotation. However, depending on the location of the tendon graft transfer, external rotation may improve but cause a limitation of internal rotation. The purpose of this study was to investigate the optimal position of tendon transfer in rTSA with the modified L'Episcopo procedure for better range of motion in rotation using fresh frozen cadavers. METHODS: Eight fresh frozen cadaveric shoulders underwent rTSA with the modified L'Episcopo procedure. To investigate the location of tendon transfer that obtains better internal and external rotation, 6 tendon transfer locations were set and the internal and external rotation at each location was measured with the arm at the side position. The 6 locations were divided horizontally into 3 locations of 225°, 270°, and 315° medial to the bicipital groove. In the lateral view, the height was divided into 2 locations which were the lower end level of the insertion of the teres minor muscle and the middle of the original insertion of the latissimus dorsi muscle. RESULTS: Three positions were significantly better for external rotation: the height of the lower edge of the teres minor insertion at 270° and 315° from the bicipital groove and the middle of the latissimus dorsi insertion at 315° from the bicipital groove compared to the height of the middle of the latissimus dorsi insertion at 225° from the bicipital groove. On the other hand, for internal rotation, the lower edge of the teres minor insertion and middle of the latissimus dorsi insertion at 315° from the bicipital groove significantly limited internal rotation compared to the other transition positions. CONCLUSION: The position of tendon transfer 270° from the bicipital groove at the height of the lower end of the teres minor insertion allowed both relatively good external rotation and internal rotation. Significant limitation of internal rotation was found with transfer 315° from the bicipital groove.