The lasso-loop, lasso-mattress and simple-cinch stitch for arthroscopic rotator cuff repair: are there biomechanical differences?

Abstract

Various stitching techniques have been described to facilitate arthroscopic repair of rotator cuff tears. The aim of the present study was to compare the biomechanical properties of the lasso-loop, lasso-mattress and simple-cinch stitch for rotator cuff repair. Twelve infraspinatus tendons were harvested from sheep and split in half. The tendons were randomized into three different stitch configuration groups for biomechanical testing: lasso-loop, lasso-mattress and simple-cinch stitch. Each specimen was first cyclically loaded on a universal materials testing machine under force control from 5 to 30N at 0.25Hz for twenty cycles. Then, each specimen was loaded to failure under displacement control at a rate of 1mm/s. Cyclic elongation, peak-to-peak displacement and ultimate tensile load were reported as mean±standard error and compared using one way analysis of variance. The type of failure was recorded. No differences in cyclic elongation (1.31±0.09mm for the simple-cinch vs. 1.49±0.07mm for the lasso-mattress vs. 1.61±0.09mm for the lasso-loop stitch, p=0.063) or peak-to-peak displacement (0.58±0.04mm for the simple-cinch, 0.50±0.03mm for the lasso-mattress and 0.62±0.06mm for the lasso-loop stitch, p=0.141) were seen between all tested stitch configurations. In the load-to-failure test, the simple cinch stitch (149.38±11.89N) and the lasso-mattress (149.38±10.33N) stitch demonstrated significantly higher ultimate load than the lasso-loop stitch (65.88±4.75N, p<0.001). All stitch configurations failed with suture pull out. The lasso-mattress and the simple-cinch stitch showed similar biomechanical properties with significant higher tensile loads needed for failure than the lasso-loop stitch.