A biomechanical study of the medial row tightening on stability of single stitch suture-bridge construct

Purpose To define the more stable knot tightening of a suture bridge when a single limb is preserved. Methods Five different sutures were tested: No. 2 Ethibond (Ethicon), Hi-Fi (ConMed Linvatec), Sutblue (SBM), SingleFlat (SBM), Hi-Fi Ribbon (ConMed Linvatec). A Surgeon's Knot was tied around a 30-mm circumference device, 6 times for each experiment. A single limb was kept to analyze failure modes of the knot. First step was to analyze which of pulling or sliding suture of the construct must be kept preventing failure of the knot. The cutting distance from the knot was evaluated at 1 mm and 4 mm with the suture loops pre-tensioned to 10 N and fixed to a second row after a 50 N tension load. The more stable construct was found: a single-pull load to 100 N and cyclic load (to 50 N for 30 cycles) experiments were conducted to evaluate the impact of cycling on knot loosening. Results The more stable construct was obtained when the non-post limb was tensioned, and the post limb was cut at 4 mm (p < 0.01). Loop circumference increased after each experiment for all tested sutures, independently of the preserved limb and the cutting distance. Elongation was significant for all tested sutures in all groups. Knot failure mostly occurred by slippage, only with tapes. Conclusions A suture-bridge construct with the non-post limb preserved and the post limb cut at a 4 mm distance from the knot provides with the best security. Sutures are safer than tapes in suture bridge. Keywords: Suture-bridge, Biomechanics, Limb, Knot, Sutures, Tapes, Rotator cuff