Objective: To determine whether axial twisting within an ending loop negatively impacts maximum load to failure and failure mode of suture knots.
Samples: 525 knots (15 samples each of 7 different suture types/sizes tested in 5 knot-twist configurations each).
Procedures: Each suture type (polydioxanone [PDO], Monoderm [polyglecaprone 25], and Nylon) and size (1, 0, 2-0, 3-0) were used to create a starting square knot, and each of the following ending square knot configurations: 0 twists, 1 twist, 4 twists, and 10 twists. Each suture was tested for failure using a universal testing machine (Instron, Instron Corp) with a 100 kg load cell at a speed of 100 mm/min. Each suture and knot was evaluated for a mode of failure using gross evaluation of the knots and video footage recorded during testing. Maximum load at failure (P-value set at .005) and failure mode (p-value set at 0.003) were recorded for each group.
Results: Maximum load at failure was decreased in knots tied within ending loops containing more twists for some types and sizes of the suture. With 4 twists, 0-PDO, 1 PDO, and 2-0 Nylon was more likely to fail at the knot than knots with 0 twists. All sutures containing 10 twists, except 3-0 Monoderm, were more likely to fail at the knot than knots with 0 twists.
Clinical relevance: The number of twists within the ending loop may not increase the risk of failure at the knot; however, it can decrease the maximum load to failure at a knot, particularly as the suture size increases.