Summary

Suture tapes show increased elongation when using a surgical knot compared to round sutures

Abstract

Introduction

Different suture materials are available for fixation of soft tissue structures in orthopedic sports medicine. Depending on the use-case, suture materials can be used either knotted, or knotless. The aim of the present study was to test different suture materials regarding their biomechanical primary stability in knotted and knotless condition. It was hypothesized that tape material displays increased elongation, in comparison to round sutures, when used in a knotted configuration.

Methods

4 suture materials (FiberWire #2 [FW2, Arthrex], SutureTape [ST, Arthrex], FiberTape [FT, Arthrex], No. 6 Ethibond [EB6, Ethicon]) of 15 cm length were knotted to a loop with 2 co-rotating and 5 counter-rotating surgical knots (n = 10 each). The loops were inserted into a testing machine (ZwickRoell) and subjected to a load of 50 N for 500 cycles, then 100 N for 500 cycles, followed by loading to failure. Furthermore, suture loops of the same length (n = 10 each) were tested in a knotless configuration, in which the suture loops were fixed to the machine using a metal clamp, without a knot. The elongation after cyclic loading to 50 N, and 100 N, as well as the failure load were compared using a one-way ANOVA.

Results

After cyclic loading to 50 N, ST showed a significantly higher elongation of 1.9 ± 0.8 mm than all other groups (p < 0.01 in each case). There were no significant differences between FW2 with an elongation of 0.5 ± 0.1 mm, FT with 0.7 ± 0.2 mm and EB6 with 0.4 ± 0.1 mm. After cyclic loading to 100 N, FW2 with 7.0 ± 0.9 mm and ST with 8.4 ± 1.7 mm showed less elongation in comparison to FT with 11 ± 1.7 mm and EB6 with 12 ± 0.8 mm (both p < 0.01). Compared to the knotless testing, all suture materials in the knotted state showed an increased elongation (knot elongation) after cyclic loading up to 100 N (p < 0.01 in each case). ST with 4.2 mm (95% confidence interval [CI]: 3.1-5.5 mm) and FT with 5.7 mm (95% CI: 4.4-7.0 mm) showed significantly higher knot elongations in comparison to FW2 with 2.0 mm (95% CI: 1.0-2.9 mm) and EB6 with 2.2 mm (95% CI: 0.4-2.2 mm) (p < 0.01). FT showed a significantly higher load to failure in comparison to all other suture materials at 785 ± 62.5 N (p < 0.01 in each case). Between FW2 with 319 ± 11 N, ST with 320 ± 22 N and EB6 with 331 ± 13 N, there were no significant differences in the failure load.

Conclusion

It was shown that ST elongated more at 50 N in the knotted structure than the other suture materials. After loading up to 100 N, increased elongation was observed for all suture materials. All materials elongated more in the knotted state, in comparison to the knotless, which can be explained by knot setting. The knot elongation was found to be higher for the tapes (FT, ST) than for the round suture materials (FW2, EB6). Despite the higher failure loads for tape materials, this could argue in favor of using round sutures, or knotless fixations for soft tissue sutures and reconstructions.