Feasibility of lower trapezius transfer extended by the infraspinatus fascia for restoration of external rotation in irreparable posterosuperior rotator cuff tears: an anatomical study.

Abstract

Lower trapezius (LT) transfer using Achilles tendon allograft or semitendinosus autograft is effective in restoring external rotation in massive irreparable posterosuperior rotator cuff tears (RCT). The purpose of this study was to evaluate if the infraspinatus fascia (IF) could be used in LT transfer to extend the LT tendon. Eight fresh-frozen whole-body cadavers were dissected using both shoulders, beach chair position. A 2.5-3cm wide bundle of the IF was dissected, from the inferior angle of the scapula up to the insertion of the LT which was then detached subperiosteally in continuity with the fascia. The extended tendon was reinforced with sutures and brought to the center of the footprint of the supraspinatus on the humerus. We measured: (a) the distance between the insertion of the LT on the scapula and the inferior angle of the scapula, estimating the length of the IF that can be harvested, (b) the distance between the insertion of the LT on the scapula and the center of footprint of the infrastinatus on the humerus, estimating the distance needed to be covered by the graft (c) the length of the extended tendon between the center of footprint of the infrastinatus on the humerus (fixation point) and its free end, estimating the length available for fixation. The mean length of the fascia that can be harvested is 125.56mm. The mean distance that needs to be covered by the graft is 100mm. The extended tendon is long enough leaving 24.69mm for fixation. The transfer of the LT extended with the IF on the footprint of the infraspinatus is feasible. It could be a viable alternative to the currently used grafts in LT transfer in irreparable posterosuperior RCT.