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Surgical knot tightening: how much pull is necessary?

Neuhofer, Stefan ; Wieser, Karl ; Lajtai, Georg ; Müller, Daniel ; Gerber, Christian ; Meyer, Dominik

In: Knee Surgery, Sports Traumatology, Arthroscopy, 2014, vol. 22, no. 11, p. 2849-2855

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    Titre
    • Surgical knot tightening: how much pull is necessary?
    Auteur
    • Neuhofer, Stefan. Orthopaedic Department, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland
    • Wieser, Karl. Orthopaedic Department, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland
    • Lajtai, Georg. Orthopaedic Department, Private Hospital Maria Hilf, Klagenfurt, Carinthia, Austria
    • Müller, Daniel. Orthopaedic Department, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland
    • Gerber, Christian. Orthopaedic Department, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland
    • Meyer, Dominik. Orthopaedic Department, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Knee Surgery, Sports Traumatology, Arthroscopy, 2014, vol. 22, no. 11, p. 2849-2855. Springer Berlin Heidelberg
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:325259
    Summary
    Purpose: High-strength sutures allow tightening of a suture knot beyond the strength of the surgeon, possibly inflicting skin damage through the gloves. This study was undertaken to evaluate whether such effort is useful and how much tensioning on a surgical knot is necessary. Methods: Three different suture materials were tested: No. 2 Vicryl™, FibreWire™, and PDS™. First, the force spontaneously applied on sutures during experimental knot tightening ("tying load”) was measured in fifteen experienced surgeons. Second, with each suture material, surgical square knots were tied with increasing, standardized loads (range 0.5-50N) using a custom-made apparatus. Thereby, knot seating after tying was evaluated, and by loading the knots to failure, evaluation for failure mode and failure load was performed. Results: FibreWire™ 5-throw square knots always failed by complete slipping of all knots (resolving), independent on the tying load. A nonlinear decrease of knot slippage and increased failure load were seen with increasing tying loads for all sutures. Major differences were seen between 0.5 and 10 N for FibreWire™ (slippage: 25mm) and PDS™ (99.6mm), whereas Vicryl™ showed major differences (22.7mm) between 0.5 and 2N. Increasing the tying load from 10 to 50N decreased the mean knot slippage from 12 (FibreWire™, ±2.6 SD), 9 (PDS™, ±1.8 SD) and 8 (Vicryl™, ±1.3 SD) mm to 6 (±2.9 SD), 3 (±1.5 SD) and 4mm (±0.9 SD), respectively. Conclusion: Slippage and self-seating of the knots under load is unavoidable even with highest tying loads. Relatively minor but possibly important differences can be seen for tying loads exceeding 2N (Vicryl™) and 10N (PDS™ and FibreWire™) for failure load and knot slippage. But also with a tying load of 50N, a minimal slippage of approximately 3mm seems unavoidable for all suture types. However, it is important to state that intense tightening does not prevent knot resolution and is only necessary in clinical situations that demand very tight sutures. Numbers and proper appliance of throws are more relevant than tying strength to reach the maximum failure load.