Optimizing arthroscopic knots using braided or monofilament suture.

Surgeons need to know how the material properties of a suture affect the security of a surgical knot. The purpose of this study was to compare the security of some clinically important arthroscopic knots when tied using a braided multifilament suture and to draw comparisons with results of similar knots tied with monofilament suture. Permanent braided polyester suture was used to test 10 knot configurations. Eight of the knots included (1) two types of initial cinching knots followed by (2) one of four combinations of half-hitches. We also tested the taut-line hitch locked with half-hitches and the original Revo knot. Each knot was subjected to cyclic loading followed by an ultimate load to failure. Clinical failure was defined as the maximum force that resulted in 3 mm of loop displacement. Force versus displacement data were obtained, and the maximal loop holding capacities were compared statistically. The Duncan loop with switched-post half-hitches and the Revo knot (Linvatec, Largo, FL) showed the highest knot-holding capacities (mean, 87N and 92N, respectively) when compared with all other configurations (P < .0001) for braided suture. A similar knot-holding capacity was described for monofilament suture using the Duncan loop locked with switched-post, reversed-direction half-hitches (mean, 81 N). All knots without post switching slipped completely at significantly lower loads than knots with post switching (monofilament, P < .001; braided, P < .0001). When compared with results of knots tied with monofilament suture, the braided switched-post configurations had smaller cyclic displacements (braided, 0.7 mm; monofilament, 1.7 mm). Although the Revo knot showed good strength for braided suture, it was significantly weaker than other configurations when tied with monofilament suture. Therefore, it is important to test the knot strength for a given suture material before applying it clinically.

Optimizing arthroscopic knots.

Arthroscopic repairs, such as those for shoulder instability, are commonly performed. However, the failure rate after arthroscopic repair appears to be higher than with open surgery. These failures may relate to the challenge of tying secure knots arthroscopically. Many knots tied arthroscopically commonly consist of an initial slip knot to remove slack, and a series of half-hitches. Half-hitches, instead of square throws, are difficult to avoid and result when asymmetrical tension is applied to the strands. For this reason, the security of knots tied arthroscopically may not be equivalent to square knots and a greater rate of failure may occur. The purpose of this study was to determine (1) the security of various arthroscopic knots under cyclic and peak loading conditions, (2) how the surgeon can modify the method or sequence of half-hitch throws to minimize knot slippage or breakage, and (3) whether using an arthroscopic knot pusher affects the security of the same knot tied by hand. The most secure knot configurations were achieved by reversing the half-hitch throws and alternating the posts. These knots performed significantly better than all other knots tested (P < .002). Thus the surgeon can control the holding capacity and minimize suture loop displacement by proper alternation of the tying strands and reversal of the loop when placing the hitches.(ABSTRACT TRUNCATED AT 250 WORDS)