Biomechanical analysis of four different medial row configurations of suture bridge rotator cuff repair

Background: Rotator cuff tendon rupture after suture bridge repair occasionally occurs at the medial row, with remnant tendon tissue remaining at the footprint. While concentrated medial row stress is suspected to be involved in such tears, the optimal suture bridge technique remains controversial. Methods: This study aimed to investigate the construct strength provided by suture bridge techniques having four different medial row configurations using artificial materials (n = 10 per group): Group 1, four-hole (two stitches per hole) knotless suture bridge; Group 2, eight-hole (one stitch per hole) parallel knotless suture bridge; Group 3, eight-hole non-parallel knotless suture bridge; and Group 4, eight-hole knot-tying suture bridge. Each construct underwent cyclic loading from 5 to 30 N for 20 cycles, followed by tensile testing to failure. The ultimate failure load and linear stiffness were measured. Findings: Group 2 had the highest ultimate failure load (mean 160.54 N, SD 6.40) [Group 4 (mean 150.21 N, SD 9.76, p = 0.0138), Group 3 (mean 138.80 N, SD 7.18, p < 0.0001), and Group 1 (mean 129.35 N, SD 4.25, p < 0.0001)]. The linear stiffness of Group 2 (mean 9.32 N/mm, SD 0.25) and Group 4 (mean 9.72 N/mm, SD 0.40) was significantly higher (p = 0.0032) than that of Group 1 (mean 8.44 N/mm, SD 0.29) and Group 3 (mean 8.61 N/mm, SD 0.31). Interpretation: In conclusion, increasing the number of suture-passed holes, arranging the holes in parallel, and a knotless technique improved the failure load following suture bridge repair.