An evaluation of knot integrity when tied robotically and conventionally (original) (raw)
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Knots Tied With High–Tensile Strength Tape Biomechanically Outperform Knots Tied With Round Suture
Orthopaedic Journal of Sports Medicine, 2021
Background: Tape-type suture material is well-accepted in arthroscopy surgery. Purpose: To compare the knot security of a high–tensile strength round suture and high–tensile strength tape with commonly used arthroscopic knots. Study Design: Controlled laboratory study. Methods: We compared the performance of No. 2 braided nonabsorbable high-strength suture with that of 1.3-mm braided nonabsorbable high-strength tape. Five commonly used arthroscopic knots were investigated: the Roeder knot; the Western knot; the Samsung Medical Center (SMC) knot; the Tennessee knot; and a static surgeon’s knot. Seven knots were tied for each combination of knots and suture types. Knots were tied on a 30-mm circumferential metal post, and the suture loops were transferred to a materials testing machine. After preloading to 5 N, all specimens were loaded to failure. The clinical failure load, defined as the maximal force to failure at 3 mm of crosshead displacement, yield load, and stiffness, were reco...
Veterinary Surgery, 2010
Objective-To evaluate the effect of 6 different knotting methods on the mechanical properties of 3 large absorbable suture materials used in large animal surgery. Study Design-In vitro mechanical study. Sample Population-Knotted suture loops (n=15 per group). Methods-Suture loops were created between two low-friction pulleys with either 2 polydioxanone, 2 polyglactin 910 or 3 polyglactin 910. Strands were tied using 1 of 6 knotting technique: square knot, surgeon knot, clamped surgeon's knot, sliding half-hitch knot (HH), Delimar knot and self-locking knot (SLK). A single cycle to failure test was performed on each suture loop with a distraction rate of 100 mm/min. Failure modes were evaluated and breaking strength, elongation to failure and stiffness were compared. Results-All loops except two HH failed at the knot by acute breaking. The double-stranded SLK was both stronger and stiffer than all other knots for each suture material. Clamping the first throw of the surgeon knot decreased load to failure significantly (143.11 AE 8.64 N) compared with not clamping (159.21 AE 6.14 N) for polydioxanone. Stiffness and elongation to failure were respectively lower and increased for 2 polydioxanone compared with both polyglactin 910 materials for all knotting techniques. Conclusions-Knotting techniques do influence structural properties of suture loops. The double strand loop conferred stiffer and stronger properties to the SLK Clinical Relevance-Clamping the first throw of polydioxanone should be avoided when tying a suture under tension even using large diameter suture materials. Using a SLK might be considered as a useful alternative when excessive tension is present.
Mechanical testing of different knot types using high-performance suture material
Knee Surgery, Sports Traumatology, Arthroscopy, 2013
Purpose This laboratory study aimed to evaluate the loop security, knot security, cyclic loading resistance and loadto-failure rate of three different knot types with establishing a new experimental setup. Additionally, the mode of failure of each knot was evaluated. Methods With the use of nonabsorbable, braided polyethylene sutures, USP size No. 2 [Hi-Fi Ò ; ConMed Linvatec], the arthroscopic knot types Dines, SMC as well as the surgeon's knot were tested using a material testing machine. The knots were tied openly as well as arthroscopically. The setup enables testing of knot configurations while eliminating friction between knot loop and its suspension points. Including all test procedures, a total of 216 knots were tested. Results All openly tied knot types and ten of each type of arthroscopically tied knots resisted against cyclic loading of 1,000 cycles. With subsequent load-to-failure testing, openly tied knot types achieved significantly higher values of tensile strength than arthroscopically tied knots. Regarding clinical failure, defined as an elongation of 3 mm, Dines knot reached highest loop as well as knot security. Knot slippage was the most common failure mechanism at an elongation of 3 mm, whereas suture breakage was evaluated most at an elongation of 6 mm. Conclusions The new experimental setup confirms the loop security of arthroscopic knot types. Using a knot pusher clinically is a key factor to attain this as compared to openly hand-tied techniques. The Dines knot presented the highest reliability. It may provide a secure tissue healing during rehabilitation and consequently can be recommended for clinical application.
Polymers, 2016
The aim of this study was to evaluate and compare the mechanical properties of five suture materials on three knot configurations when subjected to different physical conditions. Five 5-0 (silk, polyamide 6/66, polyglycolic acid, glycolide-e-caprolactone copolymer, polytetrafluoroethylene) suture materials were used. Ten samples per group of each material were used. Three knot configurations were compared A.2=1=1 (forward-forward-reverse), B.2=1=1 (forward-reverse-forward), C.1=2=1 (forward-forward-reverse). Mechanical properties (failure load, elongation, knot slippage/breakage) were measured using a universal testing machine. Samples were immersed in three different pH concentrations (4,7,9) at room temperature for 7 and 14 days. For the thermal cycle process, sutures were immersed in two water tanks at different temperatures (5 and 55˝C). Elongation and failure load were directly dependent on the suture material. Polyglycolic acid followed by glycolide-e-caprolactone copolymer showed the most knot failure load, while polytetrafluoroethylene showed the lowest (p < 0.001). Physical conditions had no effect on knot failure load (p = 0.494). Statistically significant differences were observed between knot configurations (p = 0.008). Additionally, individual assessment of suture material showed statistically significant results for combinations of particular knot configurations. Physical conditions, such as pH concentration and thermal cycle process, have no influence on suture mechanical properties. However, knot failure load depends on the suture material and knot configuration used. Consequently, specific suturing protocols might be recommended to obtain higher results of knot security.
Knot Integrity as a Function of Suture Expiration
Journal of Surgical Education, 2011
To test the integrity of knots tied with expired suture and non-expired suture, using 5 different suture materials.Knots were tied using expired and non-expired chromic catgut, polyglactin 910, polydioxanone, silk, or coated polyester. Expired sutures were a mean of 10.5 years past the date of expiration stamped on the packaging. Suture packaging was inspected for any flaws or humidity. There were 116 knots with expired suture and 109 non-expired knots. All knots were tied by hand. Suture was soaked in 0.9% sodium chloride for 60 seconds and subsequently transferred to a tensiometer where the tails of the knots were cut to 3 mm length. We compared the tensile strength of knots using a tensiometer to pull the knots until the suture broke or untied. A minimum of 30 knots were needed in order to detect a statistically significant main effect for expired and non-expired sutures with 80% power and a 5% chance of type I error.A total of 225 knots were tied. Overall, we found no difference in mean tension between expired suture (77.5 ± 31.7 N) and non-expired suture at failure (81.9 ± 30.2 N). All the sutures broke at the knot and none untied. Expired chromic and polydioxanone were significantly weaker than the non-expired suture of the same material (p = 0.002 and p = 0.001, respectively). There was no statistically significant difference in tensile strength between expired absorbable or permanent suture materials. Based on a univariate analysis of variance ([SCAP]ANOVA)[R] there was no difference in the tension at failure between expired and non-expired sutures with suture packet as a covariate. No suture untied when knotted with expired suture.Under laboratory conditions, expired chromic and polydioxanone sutures broke at lower tensile strength than non-expired sutures of the same material.
Canadian journal of veterinary research = Revue canadienne de recherche vétérinaire, 2016
The influence of the type of material used, knot configuration, and use of an additional throw on the tensile force at failure, the elongation, and the mode of failure of different configurations of linear sutures and knotted suture loops was evaluated in this in-vitro mechanical study. We hypothesized that all types of knots would significantly influence the initial force and elongation of suture materials and would influence the force and elongation at which the knotted loops break, but not their mode of failure. A total of 432 samples of 4 types of size 3-0 suture material (polydioxanone, polyglecaprone 25, polyglactin 910, and nylon), representing 9 configurations, were tested in a tensiometer. The configurations were 1 linear suture without a knot and the following loops: square (SQ) knot; surgeon's (SU) knot; granny (GR) knot; and sliding half-hitch (SHH) knot using either 4 and 5 or 3 and 4 throws, depending on the material. For polydioxanone, SQ and SU knots did not decr...
2021
In this study, the objective was to compare the knot integrity and efficiency between the two most commonly utilized surgical knots – the two double throws (2DT) and three single throws (3ST) knots via experimental testing and computational modelling. A single suture material Polyglactin 910 (Vicryl; Ethicon, Inc) was selected for this study and all sutures were of a 4-0-gauge size. 12 knotted suture samples (n=12) were prepared for each of the two surgical knot configurations. A tensile testing machine a load cell of 100N was utilized. The knots were loaded via a crosshead movement rate of 1mm/s throughout the test until knot failure, either by suture rupture at the knot or knot slippage. To test knot strength, assuming slippage does not occur, 3D scaled computational models of the 2DT and 3ST knots were created in SOLIDWORKS, and exported to a finite element analysis (FEA) software ABAQUS. The sutures were subjected to increasing static forces until the yield stress within the sut...
Suture End Length as a Function of Knot Integrity
Journal of Surgical …, 2009
To evaluate tension at the failure of 3 commonly used sutures when suture ends were cut to 3 lengths. STUDY DESIGN: Knots were tied using U.S. Pharmacopeia Size 0 -0 polyglactin 910, silk, or polydioxanone sutures. The knots were tied randomly on a jig by the same surgeon. End lengths were then cut to random lengths of 0, 3, and 10 mm. We compared the individual knot strength when subjected to tensile forces via tensiometer with the point of knot failure, which was defined as untying and/or breaking of the knot.
Assessment of Four Tissue Models on Knot Tensile Strength
Journal of Surgical Education, 2012
OBJECTIVE: To determine whether the tissue model onto which a knot is tied influences the knot's tensile strength. STUDY DESIGN: Zero-gauge, nonexpired, silk, polyglactin 910, polydioxanone, and polypropylene sutures were tied on 4 different mock tissue models. The tissue models were standard metal hex head screw, uncooked chicken breast, a tube of packaged "string" cheese, and a cylinder of bubble wrap. The knots were tied without a surgeon's knot and with 4 additional square knots (1 ϭ 1 ϭ 1 ϭ 1 ϭ 1). The knots were tied by a single obstetrician/gynecologist investigator (J.M.D.) over the period of 1 week to minimize fatigue. We compared the knots when subjected to a tensiometer until the suture broke or untied. A minimum of 20 knots per group were needed to detect a moderate effect size with a power of 85% and a type I error rate of 5%. RESULTS: A total of 407 knots were tied with 4 types of material (silk, polyglactin 910, polydioxanone, and polypropylene), using 4 different models (chicken, bubble wrap, cheese, and metal). Among the knot failures, 113 of 407 untied rather than broke (28%). No differences in the likelihood of knots coming untied between the different models (p ϭ 0.34) or tension at failure (p ϭ 0.81) were noted. A 4 ϫ 4 factorial analysis of variance (ANOVA) was conducted to determine the effects of the suture material and model type on tension at failure and whether there was any interaction between the 2 factors. No significant difference was observed in the interaction between suture material and model type (p ϭ 0.35), and no effect for model type was found (p ϭ 0.22). CONCLUSIONS: Tissue models that use materials more similar to human tissue do not seem to influence knot strength when compared with standard metal models. We propose that it is possible to have an accurate understanding of how knots withstand force and to simulate an in vivo environment by using low-cost, easily accessible natural and synthetic materials for the mechanism onto which the knot is tied.