Knots Tied With High–Tensile Strength Tape Biomechanically Outperform Knots Tied With Round Suture

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 recorded. A 2-way analysis of variance was used to determine differences between the groups. Results: Both suture type and knot type significantly affected the clinical failure load, yield load, and stiffness ( P = .002). The high-strength tape resulted in a significantly greater clinical failure load than the high-strength suture in the case of the Roeder knot, Western knot, and SMC knot ( P = .027, .005, and .016, respectively). When the high-strength round suture was used, the Roeder knot, Western knot, and SMC knot resulted in significantly smaller clinical failure loads compared with the Tennessee knot ( P = .011, .003, and .035, respectively) and the static surgeon’s knot ( P < .001 for all). When the high-strength tape was used, the Roeder knot, Western knot, and SMC knot resulted in significantly smaller clinical failure loads compared with the static surgeon’s knot ( P = .001, .001, and .003, respectively). Conclusion: The results of this study indicated that arthroscopic knots tied using 1.3-mm high-strength tape biomechanically outperformed knots tied using a No. 2 high-strength suture. While the static surgeon’s knot exhibited the best biomechanical properties, the Tennessee knot resulted in generally better biomechanical properties among the arthroscopic sliding knots. Clinical Relevance: Elongation and loosening of tied knots possibly affects the clinical results of repaired constructs.

How to tie dangerous surgical knots - easily. Can we avoid this?

E H Drabble**, S Spanopoulou*, E. Sioka*, E Politaki*, I K Paraskeva*, E Palla*, L Stockley***, D Zacharoulis* (* University of Thessaly, Greece, **Clinical lead BSS course RCS England, Consultant Surgeon, University of Plymouth Hospitals NHS Trust***University of Plymouth, England) (Data statement: 'Technical appendix, statistical code, and dataset available from the Univrersity of Plymouth Data repositry Corresponding author: Eric Drabble, c/o 42 Skylark Rise, Plymouth PL6 7SN, Devon, UK [email protected] +44 7533 186772 Abstract Objective: Secure knots are essential. Previous publications have concentrated on security of different knot types, but could individual technique be important? Determine whether the technique of formation of each layer of a surgical knot is important to the security of the knot formed. Design study: Prospective analysis of technique on knot security Materials and methods: Senior and resident surgeons, and medical students, tied knots with three techniques, using four study materials, 2/0 polyglactin 910 (vicryl), 3/0 polydioxanone (PDS), 4/0 poliglecaprone 25 (monocryl) and 1 nylon (Ethilon); a standard flat reef knot (FRK), knots tied under tension (TK), and knots laid without appropriate hand crossing (NHCK). Each knot technique was performed reproducibly, and security determined by distraction with increasing force, till each material broke, or the knot separated completely. Results: 20% of flat reef knots (FRK) tied with all suture materials slipped; all knots tied with the other two techniques, with all materials, slipped, TK (100%) and NHCK (100%). The quantitative degree of slip, was significantly less for FRK (mean 6.3% 95%CI 2.2-10.4%) than for TK (mean 312% 95%CI 280.0-344.0%) and NHCK (mean 113.0% 95%CI 94.3-131.0%). The mean lengths of suture in loops held within knots, tied under tension (TK mean 17.0mm 95%CI 16.3-17.7mm), and tied without appropriate hand crossing (NHCK mean 16.3mm 95%CI 15.9-16.7mm) were significantly lower than for flat reef knots (FRK mean 25.1mm 95%CI 24.2-26.0mm). The first two types of knot may have tightened more than anticipated, in comparison to flat reef knots, with potential undue tissue tension. Conclusion: Meticulous technique of knot tying, is essential for secure knots, appropriate tissue tension, and the security of anastomoses and haemostasis effected

Polycaprolactone/ultra-high molecular weight polyethylene partially absorbable suture with improved mechanical performances for tendon and ligament repair

Orthopedic suture, as an implantable surgical device for skeletal and soft tissue connection, is vital in tendon or ligament injury repair. Resorbable therapy approaches exhibit excellent biocompatibility in the field of suture materials but lack a long-term fixation effect in orthopedic treatment. Herein, this study focused on a series of partially absorbable orthopedic sutures, which were composed of absorbable polycaprolactone (PCL) multifilament and non-absorbable ultra-high molecular weight polyethylene (UHMWPE) multifilament. Comprehensive in vitro mechanical evaluations were conducted to probe the relationship between material composition and mechanical properties of the sutures. The results showed that the partially absorbable sutures, especially P/U = 50/50 and P/U = 25/75, exhibited significant improvements in mechanical properties compared to single-material sutures. The tensile strength of P/U = 50/50 and P/U = 25/75 was 180.99 and 210.91 N, respectively, which was about two times higher than that of absorbable PCL suture P/U = 100/0 (62.42 N). Furthermore, their suture-to-suture friction force was 1.89 times and 2.51 times that of non-absorbable UHMWPE suture P/U = 0/100, respectively, which guaranteed good knot security. Compared with the clinically used orthopedic suture Ethibond (110 N), P/U = 50/50 and P/U = 25/75 also presented superior tensile properties. Notably, P/U = 50/50 and P/U = 25/75 had similar tensile curves to that of the native tendon/ligament, which might be beneficial to tissue healing. Moreover, the R2 of Eyring's model to simulate the creep curves of each suture was higher than 0.99, which indicated that Eyring's model could be used in predicting the long-term creep behavior of the sutures.

THE INFLUENCE OF VARIOUS MICROENVIRONMENTAL FACTORS ON BIOMECHANICAL FEATURES OF DIFFERENT SUTURE MATERIALS USED IN HEPATO-PANCREATO-BILIARY SURGERY

The key features of any suture material, such as its tensile strength, knot security, resorbability, handling characteristics and biological behavior must be taken into account during the selection process. These biomechanical features may be variable in different microenvironmental conditions in the human body in which the sutures are placed due to the influence of numerous local biohumoral factors. We have reviewed the data on the impact of pancreatic juice and bile, various pH conditions, chemotherapy and heat on different suture materials behavior. It is suggested that in pancreatic and biliary surgery polydioxanone sutures should be used. The review has also demonstrated that absorbable suture materials were more sensitive to pH than non-absorbable sutures. In addition, polyglyconate sutures were the strongest of all absorbable synthetic sutures when exposed to heat and cytotoxic drugs. This review provides a better basis for the selection of suture materials for specific applications.

The effect of pulsed lavage irrigation on suture knot security

Purpose: The purpose of this study was to determine the effect of low-pressure and pulsed lavage irrigation on suture knot security. Methods: Ninety-tied suture loops were measured for baseline circumference and then subjected to no irrigation, bulb syringe irrigation, or pulsed lavage irrigation. The sutures were placed under a load and then measured for final circumference. A larger circumference difference indicated poorer knot security. Results: There was a statistically significant difference in the knot security between all three groups ( p < 0.001). Pulsed lavage resulted in the greatest circumference increase (0.52 ± 0.19 mm), followed by bulb syringe (0.24 ± 0.18 mm), and lastly no irrigation (0.08 ± 0.00 mm). None of the groups had any catastrophic failures. No knots met the predetermined criteria for knot failure. Conclusion: Pulsed lavage irrigation resulted in a statistically significant decrease in suture knot security as compared to bulb syringe irrigation and no irrigation. None of the groups met the currently accepted criteria for clinical suture failure, which has a relatively arbitrary value. While the available literature does not discuss increases in loop circumference for specific orthopedic applications, this small difference suggests that pulse lavage is unlikely to have a clinically significant impact on the suture integrity for most orthopedic procedures.

Comparing the Influence of Different Overhand/Underhand Stacking Combinations of Reversing Half-Hitches on Alternating Posts on Arthroscopic Knot Security

Introduction Previous literature demonstrated the importanceof stacking at least three reversing half-hitches on alternating posts(RHAPs) following arthroscopic knot placement. However, RHAPsconstruction involves looping the suture in either an “overhand” or an“underhand” manner as it relates to the post, which may affect knotsecurity. This study investigated the presently unidentified influenceof different stacking combinations of three RHAPs and suture materialon arthroscopic knot security. Methods Four different RHAPs stacking combinations were tiedwith three different suture materials. Ten knots of each configurationwere tied using each suture material, resulting in 120 evaluated knots.A single load-to-failure test was performed. The mode of failure andmean ultimate clinical failure load were recorded. Results Different overhand/underhand stacking combinations ofthree RHAPs had a statistically significant effect on arthroscopicknot strength and security; however, all combinations surpassed theminimum ultimate clinical failure threshold. Knots constructed witheither Force Fiber® or braided fishing line had mean ultimate clinicalfailure loads of greater than 200 N and most commonly failed due tosuture material breakage (100%, 60 - 80% respectively). Conversely,FiberWire® demonstrated lower mean ultimate clinical failure loadsand had a higher incidence of elongated but intact failure (60 - 90%). Conclusion Different overhand/underhand stacking combinationsof three RHAPs yielded an arthroscopic knot capable of secure tissuefixation. A significant effect was observed for suture materials on theknot strength. This study increases our understanding of suitableRHAPs construction following arthroscopic knot placement that canlead to improving the ultimate clinical failure loads of constructedarthroscopic knots observed between orthopedic surgeons.

A biomechanical comparison of different tying techniques of a double-stranded looped suture

Purpose: This study aims to assess the biomechanical performance of different tying techniques of a double-stranded looped suture (DSLS). Methods: Loop and knot security of DSLS tying techniques (nice knot (NK), modified nice knot (MNK), double-twist knot (DTK), and double-barrel knot (DBK)) were compared. The square knot of DSLS (SKD) and the square knot of single-stranded suture (SKS) had been used as references. Twenty-four loops of each configuration were created using No. 2 Fiberwire (Arthrex, Naples, Florida, USA) and tested with a material testing machine. Samples were loaded with 10 N preloads for loop security assessment. Knot security was subsequently evaluated. Twelve loops of each knot were loaded to failure. The rest were subjected to cyclic load testing and the elongation at the 50th and 1000th cycles were measured. Knot bulkiness was determined by measuring knot height before testing. Data were compared with analysis of variance and post hoc tests. Statistical significance was p < 0.05. Results: All knots showed no statistically significant difference in displacement with preload. The load-to-failure was highest in NK, followed by MNK, DTK, DBK, SKD, and SKS. The cyclic loading test at the 50th cycle and the 1000th cycle demonstrated that NK has significantly less displacement than the others except MNK. DTK provided a minimal average knot height followed by NK, SKS, DBK, MNK, and SKD. Conclusion: The different tying techniques in DSLS provided the similar loop security but different knot security and knot bulkiness. NK and MNK are biomechanically superior to the other knots, whereas DTK is the least bulky. The findings in the present study may help set the guide for the surgeons to select the tying technique of DSLS to best suit their requirement.