Shortcuts in Arthroscopic Knot Tying

Abstract

Background: Shortcuts for throwing 3 alternating reversed half-hitches on alternating posts (RHAPs), in which the post is switched by alternating strand tension to “flip” the knot, have been advocated but never validated in a biomechanical study. Hypothesis: Shortcut tying techniques will affect knot security or loop security. Study Design: Controlled laboratory study. Methods: A single surgeon tied 90 knots using No. 2 FiberWire through an arthroscopic cannula. Half had a static “surgeon’s base,” and half had a Tennessee slider base. Three techniques were used to create 3 RHAPs: (1) rethreading, (2) knot “flipping” where half-hitches were tensioned by past-pointing, and (3) knot “flipping” where half-hitches were tensioned by alternating past-pointing and over-pointing. Each knot was subjected to a preload of 5 N, followed by 1000 cycles of 5 N to 45 N at 1 Hz, and a single load to failure. Results: When compared with Tennessee knots, surgeon’s knots had a lower incidence of knot slippage and catastrophic failure as well as higher loads to clinical and ultimate failure. Shortcut techniques did not affect the properties of surgeon’s knots. However, when used to secure Tennessee knots, past-pointing decreased load to clinical failure and ultimate load to failure. Over-pointing increased the incidence of knot slippage and catastrophic failure and decreased load to clinical failure and ultimate load to failure. Loop security was marginally increased by both past-pointing and over-pointing. Conclusion: When all tying techniques are considered, surgeon’s knots outperform Tennessee sliding knots. Shortcut techniques do not alter the properties of surgeon’s knots. However, when used to secure Tennessee sliding knots, shortcuts lead to unacceptably high rates of knot slippage and catastrophic failure as well as decreased knot security. Clinical Relevance: The outcomes of arthroscopic rotator cuff or labral repairs can be compromised when using shortcut tying methods to secure sliding Tennessee knots.