How many knots are necessary to achieve knot security of two high strength suture tapes? A biomechanical comparative analysis.

Introduction: According to current clinical practice, a minimum of 7 knots are required to provide secure hold in high-strength sutures. A new technology featuring a suture tape with a salt-infused silicon core has been recently developed, potentially reducing the number of needed knots.

Aims: to (1) assess the influence of number of knots on tape security, (2) evaluate the effect of different ambient conditions on knot security, and (3) compare the biomechanical competence of the novel versus a conventional suture tape.

Materials And Methods: A conventional suture tape (ST, SutureTape) was considered for knot tying together with the novel suture type (DT, Dynatape). Specimens were assigned to receive different number of knots, ranging from 3 to 7, and to be exposed to different media during tying-air (dry), saline solution (wet), and fat (fatty-wet). Seven specimens were considered for each suture type, knot number and ambient condition. With knotted sutures mounted between two roller bearings, quasi-static tensile ramp tests were performed to evaluate knot slippage, ultimate force at rupture, and minimum number of knots preventing suture unraveling for each suture tape and condition.

Results: Whereas the ST ruptured without unraveling with a minimum of 6 knots in all specimens and ambient conditions, the minimum number of knots for a DT rupture without unraveling was 6 in dry, 4 in wet, and 5 in fatty-wet condition. Ultimate force at rupture with a minimum number of needed knots did not differ significantly between ST and DT (p ≥ 0.067), in contrast to knot slippage that was significantly bigger for ST versus DT in wet and fatty-wet conditions(p ≤ 0.001).

Conclusions: In fatty-wet conditions-related to open surgery-the novel Dynatape suture tape requires 5 instead of 7 knots to achieve their security. In wet conditions-related to arthroscopic surgery-this number can be reduced to 4 knots. In contrast, the conventional SutureTape needs 6 knots to provide security in all conditions.