Novel single-loop and double-loop knot stitch in comparison with the modified Mason-Allen stitch for rotator cuff repair

In rotator cuff repair, strong and long-lasting suturing techniques that do not require additional implants are needed. This study examines the ultimate load to failure and the Young’s modulus at the suture–tendon interface for a novel single-loop knot stitch and double-loop knot stitch. These values are compared to those of the modified Mason–Allen stitch. Twenty-four infraspinatus muscles with tendons were dissected from porcine shoulders (twelve Goettingen minipigs). The preparations were randomly allocated to three groups of eight samples. Load-to-failure testing of the single-loop knot stitch, the double-loop knot stitch and the mMAS were performed using a Zwick 1446 universal testing machine (Zwick-Roell AG, Ulm, Germany). The highest ultimate load to failure for the three techniques occurred with the double-loop knot stitch with a median value of 382.2 N (range 291.8–454.2 N). These values were significantly higher than those of the single-loop knot stitch, which had a median value of 259.5 N (range 139.6–366.3 N) and the modified Mason–Allen stitch, which had a median value of 309.3 N (range 84.55–382.9 N). The values of the single-loop knot stitch and the modified Mason–Allen stitch did not differ significantly. Regarding the Young’s modulus, no significant differences were found between the double-loop knot stitch with a median value of 496.02 N/mm² (range 400.4–572.6 N/mm²) and the modified Mason–Allen stitch with 498.5 N/mm² (range 375.5–749.2 N/mm²) with respect to the stiffness of the suture–tendon complex. The median value for the Young’s modulus of the single-loop knot stitch of 392.1 N/mm² (range 285.7–510.6 N/mm²) was significantly lower than those of the double-loop knot stitch and modified Mason–Allen stitch. This in vitro animal study demonstrated that both the single-loop knot stitch and the double-loop knot stitch have excellent ultimate load-to-failure properties when used for rotator cuff repair. The introduced single-loop knot stitch and double-loop knot stitch offer an alternative to other common used stitch techniques in rotator cuff repair.