Influence of prolonged immersion on the resistance of arthroscopy knots in biological media

SummaryIntroductionBiomechanical studies of arthroscopic knots have been performed on sutures that were tied manually and tested immediately after tying. We performed this study to evaluate the knot and the suture during the healing phase, which was not evaluated in these previous studies. Our hypothesis was that the biomechanics features of arthroscopic knots may change in relation to the duration of incubation in biological media simulating synovial fluid. Thus our goal was to study the influence of incubation for 30 days in biological media simulating body fluid using a device to standardize knot tying and allow comparison of arthroscopic sutures.Materials and methodsThree Ultra-High Molecular Weight PolyEthylene (UHMPWE) sutures (Fiberwire, Orthocord and Maxbraid) were tested with a self-locking slip knot (SMC knot). Sixty identical knots were tied using a standardized device, and divided into two groups: the control group « D0 » and the group « D30 » where the knots were soaked in biological media simulating body fluid for 30 days. Cyclic loading tests were then performed on the knots in each group using a machine to define four variables: clinical failure, ultimate failure, knot slippage and the characteristics of failure.ResultsThere was no significant difference between the two groups for knot resistance at clinical failure or ultimate failure, without regard to the suture, (P < 0.05). After cyclic loading, the most slippage occurred in the Orthocord (≈5.6 mm) then the Maxbraid (≈3.55 mm) and the Fiberwire (≈2.51 mm). The only suture whose slippage was influenced by the duration of incubation was Orthocord. At clinical failure, the loop that slipped the most was the Orthocord suture (≈5.45 mm) then the Fiberwire (≈4.8 mm) and the Maxbraid (≈4.1 mm). In the Orthocord and Maxbraid sutures, knot slippage after clinical failure significantly increased with the duration of suture incubation (P < 0.05). The reason for failure was breakage from tearing of suture fibers in all cases.ConclusionProlonged incubation of arthroscopic suture knots influences slippage, which could result in unsuccessful primary attachment of the tendon during the healing phase.Level of evidenceLevel IV. Biomechanical study.