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 fixationrestore insertion site anatomy,with excellent results.We compared the biomechanical properties of double-row andtranstendon 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 repairedwith a double-row suture anchor technique.This comprised placement of 2 medial anchors with horizontal mattresssutures at an angle of ≤45° into the medial margin of the infraspinatus footprint,just lateral to the articular surface,and 2lateral anchors with horizontal mattress sutures.Standardized,50% partial,articular-sided infraspinatus lesions werecreated in the contralateral shoulder.The infraspinatus tendon from the contralateral shoulder was repaired using twoanchors with transtendon single-row mattress sutures.Each specimen underwent cyclic loading from 10 to 100 N for 50cycles,followed by tensile testing to failure.Gap formation and strain over the footprint area were measured using amotion 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 withthe 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 wassignificantly smaller (P<0.05) when compared with the double-row repair.Also,it had a higher mean ultimate tensile loadand stiffness.Conclusions For grade Ⅲ partial articular-sided rotator cuff tears,transtendon single-row fixation exhibited superiorbiomechanical properties when compared with double-row fixation.