Biomechanical comparison of double-row versus transtendon single-row suture anchor technique for repair of the grade III partial articular-sided rotator cuff tears

Background For partial-thickness tears of the rotator cuff, double-row fixation and transtendon single-row fixation restore insertion site anatomy, with excellent results. We compared the biomechanical properties of double-row and transtendon single-row suture anchor techniques for repair of grade III partial articular-sided rotator cuff tears. Methods In 10 matched pairs of fresh-frozen sheep shoulders, the infraspinatus tendon from 1 shoulder was repaired with a double-row suture anchor technique. This comprised placement of 2 medial anchors with horizontal mattress sutures at an angle of <= 45 degrees into the medial margin of the infraspinatus footprint, just lateral to the articular surface, and 2 lateral anchors with horizontal mattress sutures. Standardized, 50% partial, articular-sided infraspinatus lesions were created in the contralateral shoulder. The infraspinatus tendon from the contralateral shoulder was repaired using two anchors with transtendon single-row mattress sutures. Each specimen underwent cyclic loading from 10 to 100 N for 50 cycles, followed by tensile testing to failure. Gap formation and strain over the footprint area were measured using a motion capture system; stiffness and failure load were determined from testing data. Results Gap formation for the transtendon single-row repair was significantly smaller (P <0.05) when compared with the double-row repair for the first cycle ((1.74+/-0.38) mm vs. (2.86+/-0.46) mm, respectively) and the last cycle ((3.77+/-0.45) mm vs. (5.89+/-0.61) mm, respectively). The strain over the footprint area for the transtendon single-row repair was significantly smaller (P <0.05) when compared with the double-row repair. Also, it had a higher mean ultimate tensile load and stiffness. Conclusions For grade III partial articular-sided rotator cuff tears, transtendon single-row fixation exhibited superior biomechanical properties when compared with double-row fixation. Chin Med J 2010;123(21):3049-3054