Tennessee Slider Research Articles

Are Suture Tape Knots as Secure as Standard Suture? A Biomechanical Study.

Background:Few studies have investigated the biomechanical performance of flat-braided suture tapes versus round-braided sutures after being knotted.Purpose:To compare the loop security and knot strength of a standard round-braided suture with 3 commercially available flat-braided suture tapes using 2 types of arthroscopic knots.Study Design:Controlled laboratory study.Methods:One standard suture (SS) and 3 suture tapes (T1, T2, and T3) were tied with the surgeon’s knot (SK) and the Tennessee slider (TS), 25 times each, by a single surgeon. Each combination of knots and sutures underwent a preload, cyclic loading, and load to failure. Outcomes were loop security (defined by loop stretch after a 5-N preload), load at clinical failure (3 mm of displacement), and load at ultimate failure (suture rupture or knot slippage). Two-way analysis of variance was used for analysis.Results:Overall, the SK group had greater overall loop security than that of the TS group (0.4 ± 0.3 vs 0.5 ± 0.3 mm of stretch, respectively; P = .020). The clinical failure load varied by suture type (P < .001) but not knot type (P = .106). For both knot types, the SS had the lowest mean ± SD clinical failure load (SK, 171 ± 49 N; TS, 176 ± 37 N), which was significantly less than that of T2 (247 ± 85 N; P < .001) and T3 (251 ± 96 N; P < .001) for the SK type and T2 (231 ± 67 N; P = .023) for the TS type. T2 sutures had the greatest ultimate failure load for both knot types (SK, 418 ± 45 N; TS, 461 ± 57 N), which was significantly greater than SS, T1, and T3 (P < .001 for all). The TS knot had greater overall ultimate failure load than the SK (375 ± 64 vs 350 ± 66 N; P < .001).Conclusion:Not all suture tape knots had the same biomechanical properties, although knot security and strength appeared to be adequate for all suture tapes as well as for SS. There was no evidence that suture tape knots are lower profile than SS knots.Clinical Relevance:Surgeons should not use suture tape based only on the assumption that it has superior biomechanical properties to a standard round-braided suture.

Learning and optimizing arthroscopic knot-tying by surgery residents using procedural simulation

IntroductionProcedural training of orthopedic surgery residents includes learning arthroscopic knot-tying. The models used comprise arthroscopy training modules of increasing complexity, although there is no procedural training guide for the acquisition of arthroscopic knot-tying skills. Few studies have focused on how residents learn arthroscopic knot-tying. The aim of our study was to determine the type of arthroscopic knot that is the easiest to perform and learn and that can be done the most successfully by orthopedic surgery residents. Materials and methodsEach participant had to learn five knots in a random order: Tennessee slider, Duncan loop, Revo knot (Surgeon's knot), Nicky knot, and the SMC (Samsung Medical Center) knot. The FAST Arthroscopy Workstation™ (Sawbones, Vashon Island, WA) was used for this study. Each participant could use a FAST Knot Tester™ (Sawbones®, Vashon Island, WA) to evaluate by themselves the biomechanical properties of the knots to optimize learning. Each participant had to rank how easy it was to learn this knot on a visual scale from 0 to 10. They also had to rank the reliability of the knots done on a visual scale from 0 to 10. Then, an independent rater assessed whether the knots were completed successfully; a knot was considered successful if it stretched by less than 3 mm when 60 N of load was applied. ResultsTen participants were included in the study; 250 knots were done and evaluated. When ranked from simplest to most complicated, the easiest knot to learn was the Surgeon's knot, followed by the Duncan loop, Tennessee slider, Nicky knot and SMC knot (p<0.0001). The overall success rate for the knots was 80%. There was a statistical trend for the Nicky being done better than the other arthroscopic knots (88% success rate). ConclusionFor orthopedics surgery residents, the surgeon's knot (Revo knot) was the easiest to learn, while the Nicky knot had the highest success rate. Level of evidenceII; prospective, randomized study with low power.

Validation of Improvement of Basic Competency in Arthroscopic Knot Tying Using a Bench Top Simulator in Orthopaedic Residency Education

To validate basic competency in arthroscopic knot tying using a unique simulator device to compare the level of training needed for learning and tying the arthroscopic knot by evaluating the tensile properties of the arthroscopic knots. Three groups of surgeons of various experience levels (postgraduate year [PGY] 1, PGY 3, and experienced surgeons) tied 2 different arthroscopic knots (Tennessee Slider, considered easier, and Weston, considered more difficult) over a 10-week period. Each group went through 3 separate stages of knot tying: stage 1, tying 8 knots without cannula or knot pusher; stage 2, tying 12 knots with knot pusher; and stage 3, tying 20 knots with knot pusher through a cannula that simulates knot tying during surgery. A single load-to-failure test was performed and ultimate clinical failure loads were recorded. Time needed to tie each knot was also recorded. At stages 1 and 2, the PGY 1 group had a significantly weak knot tensile strength (Tennessee Slider stage 1: 60 v 129N, P= .001; Tennessee Slider stage 2: 69 v 132N, P= .0029; Weston stage 1: 73 v 184N, P= .0000; Weston stage 2: 125 v 173N, P= .0045) and were slower (Weston: 56 v 30seconds, P= .0010) than the experienced surgeon group for both knots. At stage 3, only the initial 2weeks of Tennessee Slider showed a significant difference between groups 1 and 3 (week 6: 87 v 118N, P= .0492; week 7: 89 v 126, P= .01485). Even though the Tennessee Slider knot is one of the easier arthroscopic knots to learn to tie, the results showed a slow trend of improvement in this knot-tying skill for group 1 after each stage. The data validated an important learning effect in all trainees in arthroscopic knot tying over a 10-week period and showed that inexperienced trainees will be able to improve their knot-tying skill with training in 3 stages with a simulator environment. The findings of this study indicated the importance of hands-on experience in performing arthroscopic knot tying, as determined by both knot performance and ultimate suture loop strength. In addition, each orthopaedic resident learned and developed his or her arthroscopic knot-tying skills and provided a foundation for his or her future practice in orthopaedic medicine.

Biomechanical evaluation of the Nice knot.

Background:The Nice knot is a bulky double-stranded knot. Biomechanical data supporting its use as well as the number of half hitches required to ensure knot security is lacking.Materials and Methods:Nice knots with, one, two, or three half-hitches were compared with the surgeon's and Tennessee slider knots with three half hitches. Each knot was tied 10 times around a fixed diameter using four different sutures: FiberWire (Arthrex, Naples, FL), Ultrabraid (Smith and Nephew, Andover, MA), Hi-Fi (ConMed Linvatec, Largo, FL) and Force Fiber (Teleflex Medical OEM, Gurnee, IL). Cyclic testing was performed for 10 min between 10N and 45N, resulting in approximately 1000 cycles. Displacement from an initial 10N load was recorded. Knots surviving cyclic testing were subjected to a load to failure test at a rate of 60 mm/min. Load at clinical failure: 3 mm slippage or opening of the suture loop was recorded. Bulk, mode of ultimate failure, opening of the loop past clinical failure, was also recorded.Results:During cyclic testing, the Nice knots with one or more half-hitches performed the best, slipping significantly less than the surgeon's and Tennessee Slider (P < 0.002). After one half-hitch, the addition of half-hitches did not significantly improve Nice knot performance during cyclic testing (P > 0.06). The addition of half-hitches improved the strength of the Nice knot during the force to failure test, however after two half-hitches, increase of strength was not significant (P = 0.59). While FiberWire was the most bulky of the sutures tested, it also performed the best, slipping the least.Conclusion:The Nice knot, especially using FiberWire, is biomechanically superior to the surgeon's and Tennessee slider knots. Two half hitches are recommended to ensure adequate knot security.

Shortcuts in Arthroscopic Knot Tying

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.

Pretzel knot compared with standard suture knots

Aim of this paper is to compare the biomechanical properties of the Pretzel knot with the selected arthroscopic knots and to test the mechanical safety of this knot. The hypothesis was that the Pretzel knot may have equal or better mechanical properties than the arthroscopic knots tested in this study. SMC, Giant, Dines, Nicky's, Tennessee Slider knots were chosen for comparison. Original and backed configuration of knots were prepared with no. 2 braided polyester sutures. Cyclic loading and load to failure tests were performed. Parameters tested were loop security, maximum elongation and load at failure. Number of steps needed for preparation of each knot was also recorded. One-way ANOVA for repeated measures was performed for all knots. Steps needed for preparation were 2 for Pretzel and Tennessee Slider, 3 for Nicky's, SMC and Dines and 4 for Giant. The Pretzel knot in original configuration had significantly better loop security compared to SMC, Dines, Nicky's and Tennessee knots (P=0.01). Loads at failure were not significantly different between knots in their original configurations. Giant and Dines knots showed better maximum elongations in cyclic loading (P=0.0059) and load to failure tests (P=0.0001). Backing up the knots with 3-RHAPs eliminated most of these significant differences. Clinically, simplicity and safety are two important components in arthroscopic knot tying. Despite its simple configuration, Pretzel knot has some similar and increased mechanical properties compared to the tested knots that are widely used.

The Effect on Loop Elongation and Stress Relaxation During Longitudinal Loading of FiberWire in Shoulder Arthroscopic Knots

This study examined the viscoelastic properties of 6 common arthroscopic sliding knots (Tennessee slider, Roeder knot, SMC knot, Duncan loop, Weston knot, and Nicky's knot) with 3 reversing half-hitches on alternating posts, tied with No. 2 FiberWire (Arthrex, Naples, FL). Knot configuration was designed to simulate a double-row rotator cuff repair with suture bridges. Constructs were loaded in 20-N increments to 100 N and held for 2 minutes to monitor the viscoelastic behavior in tension. Suture was also tested without tying a knot. Stress relaxation increased with loading but did not differ between knot configurations. Initial elongation was highest during the first loading to 20 N. Relaxation was greater for the Roeder knot at 20 N and for the Roeder and SMC knots at 80 N (P < .05) when compared with the loop with no knot. Elongation was greatest for the Roeder knot throughout all loads. This difference was significant at 60 N compared with the knotless loop. At 100 N, all knots showed greater elongation than the knotless loop (P < .05). Testing of suture, without any knots, accounted for more than 75% of the overall stress relaxation and loop elongation of the suture-knot construct. In our in vitro evaluation of the Tennessee slider, Roeder knot, SMC knot, Duncan loop, Weston knot, and Nicky's knot in a simulated suture bridge construct, knot configuration was not a variable that influenced elongation or stress relaxation. Overall response was primarily due to the suture itself. With the exception of the Roeder knot, relaxation was similar provided that a secure knot was formed at the time of original tying. With the evolution of surgical devices, the reliance on knots is decreasing. The results of this study suggest that using knotless techniques for securing the rotator cuff will not change the stress relaxation characteristics of the suture bridge.

Biomechanical Characteristics of 9 Arthroscopic Knots

To determine the optimal arthroscopic slipknot through comparison of ease of placement, loop security, knot security, and amount of suture material needed using a new suture material. Nine commonly used arthroscopic knots (Dines, Field, Nicky, Hu, San Diego, Snyder, Tennessee slider, Triad, and Tuckahoe) were tested by use of modern suture material, FiberWire (Arthrex, Naples, FL), with the Instron materials testing machine (Instron, Norwood, MA) for ease of knot placement (forward and backward sliding), loop security, and knot security. The amount of suture material needed to create the knot was compared by use of the knot weight. Analysis of variance with Kruskal-Wallis analysis and Bonferroni correction (alpha < .01) was used to compare different knots. The Tennessee slider knot sustained the greatest force at failure (269 N), the greatest knot resistance (32 N), and the smallest mass (8.5 mg). The Dines was the only knot superior in all 3 knot placement categories. The Nicky held the most loop force (66 N), and the Tuckahoe had the greatest loop resistance (20 N) (P < .01 for all except mass [P < .05]). Our study comprehensively presents ease-of-placement and security characteristics of 9 common and new arthroscopic knots using modern FiberWire suture. The Tennessee slider knot showed superior characteristics in knot security and knot mass. The Dines knot was the most ideal knot to place. However, the surgeon will need to review the individual knot characteristics and select the knot most suited to application. This study analyzed 9 arthroscopic knots with modern suture material and identified those with superior characteristics.

Cyclic Load and Failure Behavior of Arthroscopic Knots and High Strength Sutures

To compare the biomechanical performance of several different sutures by evaluating knot security and load to failure strength using different arthroscopic knots. Eight different No. 2 sutures (Ethibond [Ethicon, Somerville, NJ], FiberWire [Arthrex, Naples, FL], Orthocord [DePuy-Mitek, Norwood, MA], Hi-Fi [ConMed Linvatec, Largo, FL], Ultrabraid [Smith & Nephew, Andover, MA], ForceFiber [Stryker Endoscopy, San Jose, CA], MagnumWire [ArthroCare, Sunnyvale, CA], and MaxBraid PE [Arthrotek, Warsaw, IN]) were tied arthroscopically into standardized loops using 6 different knots (Weston, Tennessee slider, Duncan, SMC, Revo, and San Diego knot) 10 times each. The suture loops were pretensioned to 10N, cycled between 10N and 45N for 1,000 cycles, and loaded to failure. The failure load for each suture, each knot, and slippage trend during cyclic loading was recorded. The Revo and SMC knots (group A) were stronger than the Tennessee and San Diego knots (group B), which were stronger than the Weston knot, which was stronger than the Duncan loop (P < .05). This pattern also coincided with the loads at which these knots slipped. Evaluating the sutures showed that Ethibond had lower failure loads than all other sutures and FiberWire showed statistically higher loads (P < .05). Duncan loops (97.5%) and Weston knots (86.3%) slipped more than other knots (P < .001), while the SMC and Revo knots slipped least. Ethibond sutures were least likely to slip. The Duncan loop and Weston knot were more likely to slip than all other knots, and caution should be exercised when tying them with high-strength sutures. The Revo, Tennessee slider, San Diego, and SMC knots were least likely to slip (P < .001). While stronger than braided polyester sutures, newer sutures containing ultra-high molecular weight polyethylene have a greater tendency to slip. Backing up knots with 4 reversed half hitches with switched posts does not guarantee knot security.

Initial Loop and Knot Security of Arthroscopic Knots Using High-Strength Sutures

There are many options for arthroscopic knots including the type of knot and suture material used. The current investigation evaluated knot properties using 3 high-strength suture materials tied in 5 common arthroscopic knot configurations. Four arthroscopic sliding knots including the Roeder, Weston, SMC, and Tennessee Slider and an arthroscopic nonsliding Surgeon's knot were evaluated. Each knot was tied with each of 3 No. 2 polyblended suture types (Fiberwire [Arthrex, Naples, FL], Ultrabraid [Smith & Nephew, Andover, MA], and Orthocord [Mitek, Raynham, MA]). Each configuration was tied 8 times, for a total of 120 samples. Loop security and knot security were then evaluated by using a previously described protocol comparing the different knot types and suture material. With respect to loop security, Orthocord performed better than the other tested suture materials, producing on average smaller knot loops. For the nonsliding Surgeon's knot, there was no difference in loop security observed between suture types. For the Roeder knot, Fiberwire had superior knot security compared with Ultrabraid and Orthocord (P < .001). For the Weston knot, Ultrabraid showed superior knot security compared with Orthocord (P < .02). Knot security for the Tenessee slider knot was better for both Fiberwire and Ultrabraid compared with Orthocord (P < .001, respectively). Similar results were seen with the SMC knot, with Fiberwire and Ultrabraid outperforming Orthocord (P < .001, respectively). The nonsliding Surgeon's knot had significantly lower mean loads to failure compared with arthroscopic sliding knots for each tested suture material (P < .02 for all comparisons). Loop security and knot security varied depending on the type of knot tied and suture material used. Arthroscopic sliding knots performed better than the nonsliding Surgeon's knot. Surgeons should try to use sliding knots instead of Surgeon's knots when using polyblend suture material. Differences between the brands in this suture category will change the characteristics of the knots thrown and may ultimately affect tissue fixation.

Ease of tying arthroscopic knots

To date, there is no comprehensive study that determines which arthroscopic knots are easiest to learn to tie. In this study, 23 surgeons in training graded 10 arthroscopic knots with regard to ease of learning and tying using a 10-cm visual analog scale for No. 2 Ethibond and No. 1 polydioxanone (PDS) II suture. Statistical analysis was performed with analysis of variance and the Tukey Studentized range (HSD) test for post hoc analysis with a significant value of P < .05. The Tennessee slider, Duncan loop, Revo knot, and Nicky's knot were the easiest knots to tie by use of both Ethibond and PDS suture. The Field knot and double-twist knot were consistently the hardest knots to tie. Knots tied with Ethibond were easier to tie than knots tied with PDS. Novice surgeons should consider using the Revo knot when developing their arthroscopic knot-tying skills. Once they have mastered this knot, they can consider adding more difficult knots to their repertoire.

Biomechanical Characteristics of 10 Arthroscopic Knots

To determine the optimal arthroscopic slip knot through comparison of ease of placement, loop security, knot security, and amount of suture material needed. Ten commonly used arthroscopic knots (Dines knot, Duncan loop, Field knot, Giant knot, Lieurance Modified Roeder knot, Nicky's knot, SMC knot, Snyder knot, Tennessee slider, Weston knot) were tested. Ten knots were tied with No. 2 Ethibond (Ethicon, Somerville, NJ) for each testing mode trial. Each knot was tested with the Instron materials testing machine (Instron, Norwood, MA) for (1) forward and backward sliding characteristics; (2) loop security prior to securing with half-hitches (by assessing load); (3) resistance to sliding; (4) knot security after securing with 3 alternating half-hitches on alternating posts (by assessing ultimate load); (5) resistance to sliding; (6) distance to failure; and (7) knot weight, to evaluate for amount of suture material needed. Analysis of variance (P < .05) was used to compare different knots, and the knot with superior characteristics in most categories was selected as the best knot. The Dines knot performed best, exhibiting superior biomechanical characteristics in 6 of 7 measured categories. The only category in which the Dines knot did not perform superiorly was forward sliding, indicating that the Dines knot can be rated as intermediate in ease of placement. Once in place, the Dines knot provides superior loop security and knot security, with use of less suture material. This study comprehensively analyzed 10 commonly used arthroscopic knots and identified the one that exhibited the best characteristics.

Simplified Arthroscopic Rotator Interval Capsule Closure: An Alternative Technique

The anatomy of the “coracoid eclipse” of the rotator cuff, the rotator interval, has been studied extensively. Its importance in shoulder stability with respect to inferior and posterior translation has been described. Historically, open repairs for instability indirectly addressed interval lesions and closure based simply on the definition of the deltopectoral approach with its subscapularis advancement and capsular shift in a “pants-over-vest” manner. With results of arthroscopic repairs of glenohumeral instability approaching those of open procedures, the importance of simplification without sacrificing outcome has become a forefront in arthroscopic shoulder surgery. We present an alternative technique for interval closure by means of a 3/32-inch smooth Steinmann pin modified at its proximal and distal ends. A standard 3-portal technique consisting of the anterior superior portal, anterior mid-glenoid portal, and the posterior superior portal is used. The technique does not require the use of a suture shuttle nor does it require the placement of the arthroscope in the subacromial space for suture tying. A Tennessee slider knot is tied intra-articularly, thus allowing for tension modification before definitive alternate locking half-hitch placement. Intra-articular knot tying also allows for added security because suture slack is eliminated, thus avoiding air knots.

Arthroscopic knots: Determining the optimal balance of loop security and knot security

Purpose: The purpose of this study was to determine the optimal knot configuration that maximized both knot and loop security when tied with 2 different types of nonabsorbable, braided suture. Type of Study: In vitro biomechanical study. Methods: Six commonly used arthroscopic sliding knots (Duncan loop, Nicky’s knot, Tennessee slider, Roeder knot, SMC knot, Weston knot) with and without a series of 3 reversing half-hitches on alternating posts (RHAPs) as well as a static surgeon’s knot were tied. Two different nonabsorbable, braided sutures were used, and a total of 7 knots were tied for each possible combination of knots and sutures, for a total of 182 knots. Each knot was tied around a 30-mm circumference post to assure a consistent loop circumference of 30 mm before “locking” the complex sliding knots by tensioning the wrapping limb of the suture. Each loop was mounted on a Material Testing System machine, and its circumference was measured at a 5-N preload to assess each knot’s ability to maintain a tight suture loop without slippage (loop security). Knot security was measured as the maximum force to failure at 3 mm of crosshead displacement or suture breakage during single-pull load testing. Results: The surgeon’s knot provided the highest force to failure and the tightest loop circumference whether tied with No. 2 Ethibond (Ethicon, Somerville, NJ) or No. 2 Fiberwire (Arthrex, Naples, FL) suture. Among the sliding knots, the Roeder knot with 3 RHAPs showed the best balance of loop security and knot security when tied with No. 2 Ethibond or No. 2 Fiberwire. Sliding knots tied without RHAPs showed low force to failure and loose suture loops whether tied with Ethibond or Fiberwire. The addition of 3 RHAPs improved knot security and, in most cases, loop security of all the sliding knots. When tying a static surgeon’s knot or a sliding knot with RHAPs, using No. 2 Fiberwire increased the force to failure over comparable knots tied with No. 2 Ethibond. All knots failed by a combination of knot slippage and suture stretch. When using No. 2 Ethibond, securing most sliding knots with 3 RHAPs or tying a surgeon’s knot changed the failure mechanism from knot slippage to suture stretch, suggesting that the maximum knot holding capacity of No. 2 Ethibond had been achieved when tying these knot configurations. However, even at failure forces twice that achieved with No. 2 Ethibond, suture slippage continued to occur with sliding knots with 3 RHAPs using No. 2 Fiberwire. This indicates that the maximum knot-holding capacity of No. 2 Fiberwire had not been achieved, and that further knot configurations should be tested. Conclusions: (1) A static surgeon’s knot provides the best balance of loop security and knot security within the knot configurations tested in this study. (2) A sliding knot without RHAPs has both poor loop security and knot security and should not be tied. (3) The addition of 3 RHAPs improves knot security of all sliding knots tested and improves loop security of most of the sliding knots tested. (4) The addition of 3 RHAPs improves the knot security of all sliding knots to adequately resist predicted in vivo loads. (5) The Roeder knot with 3 RHAPs provides the best balance of loop security and knot security within the sliding knot configurations tested in this study regardless of suture type. (6) Tying a surgeon’s knot or a sliding knot with 3 RHAPS using No. 2 Fiberwire increases knot security over the same knot tied with No. 2 Ethibond. Clinical Relevance: This study identifies the static and sliding configurations of commonly used arthroscopic knots in order to aid the surgeon in choosing the most biomechanically effective knot for use in arthroscopic surgery.

Failure characteristics of various arthroscopically tied knots.

The current study evaluated multiple arthroscopic knot configurations and compared their properties with open, hand-tied square knots. This is an experimental study done on a material testing system. Number 2 Ethibond Extra and Number 1 Polydioxanone sutures were used. Four types of sliding knot configurations were tested: the Duncan loop, the Tennessee Slider, the Savoie-Modified Roeder, and the Lieurance-Modified Roeder. Two types of nonsliding knots were tested: the Revo knot and a knot consisting of alternating half-hitches tied with the Sixth Finger Knot Pusher. Ten knots were tied of each configuration, using strict arthroscopic technique. Each knot was backed-up with four half-hitches using post switching technique. Knots were tied around two rings and then transferred wet to a materials testing machine. The knots were tested until ultimate failure, with note of clinical failure at 3 mm. Ethibond suture using the Revo knot, the Lieurance-Modified Roeder knot, and the Savoie-Modified Roeder knot were similar in strength to the square knot with comparable failure modes. Polydioxanone suture was more variable; the Revo knot, the Savoie-Modified Roeder, the Tennessee Slider, and the Duncan loop were comparable with hand-tied square knots. All of the open and arthroscopic suture loops tested in this study failed by the suture loops expanding to greater than 3 mm before ultimate failure occurred. The surgeon choosing arthroscopic repair techniques should be aware of the differences in suture material and the variation in knot strength afforded by different knot configurations.

The double-twist knot: A new arthroscopic sliding knot

A safe and easy-to-tie sliding knot is necessary for arthroscopic repair of rotator cuff tears and glenoid labrum lesions. We describe the double-twist knot (DTK) technique, having tested the knot's tensile strength and compared it with other commonly used arthroscopic knots. The DTK is a modified Lark's head knot that can be tied only on a double suture. A No. 2 braided polyester suture was used to test the DKT against the Tennessee slider knot and Snyder's knot by means of a material testing system. Results showed a statistically significant (P < .001) higher tensile strength with the DTK than with the other 2 knots. The rationale for using a stitch with a double suture is to double the tensile strength while using the same number of surgical steps and operating time as with single-suture stitches.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 7 (September), 2002: pp 815–820

Significance of the internal locking mechanism for loop security enhancement in the arthroscopic knot

Purpose: Secure tissue fixation of an arthroscopic knot depends on the security of the initial loop and additional locking half-hitches. The purpose of this report is to evaluate the loop and knot security relative to the internal locking mechanism of arthroscopic slip knot. Type of Study: This is an experimental study designed for knot and loop security on a material testing system. The measurements were carried out in a blinded fashion in which the tester was not aware of the type of knot being tested. Methods: Five configurations of arthroscopic knots (overhand throw, Duncan loop, Revo knot, Tennessee slider, and SMC knot) were created around a 5-mm diameter metal bar using a No. 2 braided suture. For each knot configuration, 10 knots were tested for displacement at cyclic loading, load to clinical failure (3-mm displacement), ultimate failure load, and mode of failure on the servo-hydraulic material testing system (MTS 858 MiniBionix test system; NITS, Minneapolis, MN). A 1-way analysis of variance was used to determine the statistical difference in displacement at cyclic loading, load to clinical failure, and ultimate failure load between each knot configuration. Results: In the cyclic loading test, the average displacement of all knots was clinically insignificant, with the average being less than 0.24 mm. The overhand throw had the worst characteristic in the load to failure test. The other 4 knots had an optimal load to failure. The SMC knot, which has an internal locking mechanism, had good loop and knot security in the load to clinical failure and ultimate failure load (P < .05). The SMC and the Revo knots failed by knot breakage (material failure) whereas the other knots failed by knot slippage (loop failure). Conclusions: The internal locking mechanism flips the post strand to convert the loop strand into a new post strand while rerouting the original post strand around a new post. An arthroscopic knot with an internal locking mechanism can enhance loop security.