Biomechanical evaluation of 3 arthroscopic self-cinching stitches for shoulder arthroscopy: the lasso-loop, lasso-mattress, and double-cinch stitches.

Abstract

The tissue-suture interface remains the most common site of failure in rotator cuff repairs. Improving stitch strengths may lead to lower failure rates. To compare biomechanical properties of 3 self-cinching stitches to the simple, mattress, modified Mason-Allen, and massive cuff stitches. Controlled laboratory study. In sum, 336 sheep infraspinatus tendon grafts were randomized among 7 stitches. Each graft was cyclically loaded on a mechanical testing system from 5 to 30 N for 20 cycles and then loaded to failure. A mixed-effect multivariate regression model was used to test significance of suture type on cyclic elongation, peak-to-peak displacement, and ultimate load. Estimated means and standard deviations are reported from the regression model. Ultimate load for the simple stitch was significantly lower than for the other stitches. The lasso-loop and mattress stitch demonstrated similar ultimate loads. The double-cinch had a higher ultimate load than the lasso-loop or mattress stitch, although it was significantly weaker than the modified Mason-Allen, lasso-mattress, and massive cuff. The lasso-mattress had a superior ultimate load to the modified Mason-Allen and a similar ultimate load to the massive cuff stitch. One significant difference was found in cyclic elongation (1.42 mm for the simple to 1.80 mm for the double-cinch), and the cinching mechanism accounted for 0.2-mm higher elongation. Self-cinching stitches lead to superior tissue-holding strength at the tissue-suture interface when compared with equivalent non-self-cinching stitches. Self-cinching stitches have greater elongation values. How these differences in cyclic elongation clinically influence gap formation at the repair site is unknown. The greater displacement seen in the self-cinching stitches is a potential concern because minimal gap formation is desired for a strong repair. The lasso-loop stitch is a stronger alternative to a simple stitch, and the double-cinch and lasso-mattress stitches are stronger alternatives to a mattress stitch.