Suture Breaking Research Articles

Poster 143: Patella Fixation Using All-Suture Versus Knotted and Knotless Solid Suture Anchors in Medial Patellofemoral Ligament Reconstruction: A Biomechanical Analysis

Objectives: Patients with recurrent patellofemoral instability are indicated for medial patellofemoral ligament (MPFL) reconstruction. Multiple different patellar graft fixation methods exist in MPFL reconstruction surgery, namely bone tunnels, interference screws, and suture anchors. Meta analysis has shown suture patellar fixation to have superior patient reported outcomes with no statistical difference in failure rates when compared to transpatellar tunnel fixation clinically. Amongst suture anchor designs, all-soft-suture anchors occupy a smaller volume than solid suture anchors, requiring a smaller diameter tunnel during placement and thus theoretically can reduce the risk of patella fracture and articular surface violation. However, there is concern that all-soft-suture anchors may be biomechanically inferior to their hard-bodied anchor counterparts. Additionally, there is a paucity of research comparing different anchor designs (knotted vs knotless) amongst hard-bodied anchors in the setting of MPFL reconstruction. The purpose of this study is to perform a biomechanical comparison of newer generation soft-bodied anchors and hard-bodied suture anchors with different fixation methods when performing an osseous-based MPFL reconstruction in a cadaveric model. Methods: Fourteen patellae were randomized into three groups: PEEK hard-body knotless (HB-knotless), PEEK hard-body knotted (HB-knotted), and soft-body knotless (SB-knotless) anchors placed at the anatomic MPFL insertions in the direct medial position and at the superomedial aspect of each patella. Prior to anchor placement, bone density at the sites of anatomic MPFL insertions was measured on standard radiographs. After anchor placement, patellae were potted, and anchors were tested in a materials test system in a cyclic regimen (10-30 N, 100 cycles) immediately followed by load-to-failure (6mm/sec). All testing was performed in line with the anchor alignment (Figure 1). Outcome measures included maximum load and cyclic creep, defined as the difference in segment length from the peak load of the first cycle to the peak load of the 100th cycle of testing. One-way ANOVA and Fisher exact tests were used to evaluate outcomes between groups. Statistical significance was set at p < 0.05. Results: Analysis included 6 SB-knotless, 14 HB-knotted, and 8 HB-knotless anchors. The groups were equivalent in age (range 30 years – 70 years; p = 0.657) and bone density (p = 0.134) in a 4:3 male-to- female ratio. There was no significant difference in cyclic creep detected between SB-knotless (3.00 ± 0.79 mm), HB- knotless (2.80 ± 0.42 mm), and HB-knotted (3.25mm ± 0.70 mm) groups (p = 0.301). HB-knotted exhibited a lower maximum load (111.30 ± 43.71 N) than HB-knotless (180.01 ± 58.87 N) (p = 0.017), but no significant difference to SB-knotless (149.34 ± 61.38 N) (p = 0.310) (Figure 2). HB- knotless and SB-knotless did not have a significant difference in maximum load (p = 0.529). When evaluating the influence of patellar anchor site on performance, there was no significant difference in cyclic creep or maximum load between direct medial and superomedial anchor positioning in SB-Knotless (p = 0.800, p = 0.800), HB-Knotted (p = 0.719, p = 0.219), or HB-Knotless (p = 0.886, p = 0.057) groups, respectively. There were 6 SB-knotless, 12 HB-knotted, and 7 HB-knotless anchors that failed by anchor pull-out, with 2 HB-knotted and 1 HB-knotless which failed either by the suture breaking within the anchor or the knot failing (Figure 3). This difference between failure mechanisms was not significant. Conclusions: Hard-body knotless anchors provide superior load to failure than traditional hardbody knotted anchors. Additionally, all-soft-suture anchors performed as well as their counterparts in both load to failure and resistance to cyclic creep. This work suggests surgeons should be comfortable using either hard-body or all-soft-suture anchors when performing osseous-based MPFL reconstructions and may consider opting for a knotless mechanism when utilizing a PEEK hard-bodied anchor for this purpose. A clinical study should take place next to validate these cadaveric findings.

The improved cortical button shows better breaking strength of sutures compared with 10 original cortical button after cyclic loading

BackgroundSuspensory cortical buttons are widely used for fixation of reconstructed ligaments during anterior cruciate ligament (ACL) reconstruction because they have high usability and a favorable fixing force. However, it is not always easy to fix a reconstructed ACL while maintaining appropriate ligament tension. Therefore, we developed an improved cortical button that provides temporary tension until suturing is completed.MethodsButton holes of our improved EndoButton are not perpendicular to the bone surface on which the button is placed, but have an angle of 45 degrees so that the button can be temporarily fixed by applying tension to the suture. The improved EndoButton and the original EndoButton (Smith & Nephew Inc., Andover, Massachusetts) were each tied to FiberWire 5/7 metric (5 M) (manufactured by Arthrex). Ten cycles of preliminary loading (0–50 N) were applied to each suture, followed by test loading (0–250 N) for 500 or 1000 cycles. Then, a tensile test was performed at a displacement velocity of 20 mm/min.ResultsThe breaking strength of the sutures of the improved EndoButton were tend to higher than those of the sutures of the original EndoButton after 1000 loading cycles (p = 0.067, d = 0.883). The moduli of rigidity of the sutures of the improved EndoButton were higher than those of the sutures of the original EndoButton after 500 loading cycles (p = 0.027) and remained almost the same regardless of the number of loading cycles.ConclusionWe found that compared with the original cortical button, the improved cortical button was better able to retain suture breaking strength and modulus of rigidity, regardless of the number of load cycles.

Closed Incisional Negative Pressure Wound Therapy Sponge Width and Tension Off-Loading: A Laboratory Model.

Closed incisional negative pressure wound therapy (ciNPWT) has become commonplace in surgery. One mechanism ciNPWT may prevent incision site complications is by off-loading tension. This study aimed to find what width sponge using ciNPWT provides the most tension off-loading.A model was designed to test tension off-loading of a wound using ciNPWT. An incision was made in an anatomy model and closed with single stitch at the central axis. Force was applied tangentially using a force gauge at a steady rate until the wound dehisced at a peak force indicated by the 5-0 suture breaking. This was repeated 10 times for the following 4 trials: no ciNPWT and ciNPWT sponges cut a 3-, 6-, and 9-cm widths with 125 mm Hg of negative pressure.The mean peak force to dehisce the wound without ciNPWT was the lowest, 28.7 N. The mean force for the ciNPWT trials was 43.0, 38.7, and 36.4 N for V.A.C. sponges of 3, 6, and 9 cm in width, respectively. There was a statically significant difference among all the trials using one-way analysis of variance with Tukey posttest analysis with a P value of less than 0.0001.Closed incisional negative pressure wound therapy was shown to increase peak force required to dehisce an incision of up to 49.7% compared with closure without. There is an inverse relationship with sponge width and tension off-loading. The smaller the sponge, the more tension is off-loaded across the incision. Closed incisional negative pressure wound therapy with a 3-cm-wide sponge required the greatest peak force for dehiscence.

A Biomechanical Comparison of Six Suture Configurations for Soft Tissue–Based Graft Traction and Fixation

The purpose of this study was to compare 6 different graft fixation techniques to determine the preparation speed, fixation security, biomechanical strength, and resultant tissue trauma. Six different techniques (10 samples each): #2 OrthoCord Krackow stitch, #2 FiberWire Krackow stitch, SpeedTrap, WhipKnot, Loop-in-loop stitch were created in the distal 3cm of 9cm bovine flexor tendons. The proximal 3cm tendon segment was clamped in a testing machine and the distal suture ends secured by pneumatic grips. 3 preload cycles (10N-100N) and 50N static load was followed by 500 cycles (50N-200N) and then loaded to failure. Graft preparation times, 100 and 500 cycle displacement, maximum failure load, stiffness, and failure mode were recorded. Representative graft preparation times were: OrthoCord Krackow (247s), FiberWire Krackow (401s), FiberLoop (177s), SpeedTrap (42s), WhipKnot (39s), Loop-in-loop (45s). No WhipKnots survived cyclic loading. 100 cycle displacements were: OrthoCord Krackow (11.5 ± 3.9mm), FiberWire Krackow (8.9 ± 1.2mm), FiberLoop (14.2 ± 6.1mm), SpeedTrap (8.8 ± 2.5mm), Loop-in-loop (10.4 ± 2.9mm). FiberLoop displaced significantly more than all others (P= .016). Maximum failure loads were: OrthoCord Krackow (364 ± 24N), FiberWire Krackow (375 ± 45N), FiberLoop (413 ± 95N), SpeedTrap (437 ± 65N), WhipKnot (153 ± 42N), Loop-in-loop (329 ± 112N). The most common failure mode was suture breaking. FiberWire containing constructs (Krackow and FiberLoop) shredded or cut through ("cheese wiring") prior to failure in a majority. SpeedTrap, WhipKnot and Loop-in-loop were quickest to create (under 1minute). The Krackow, SpeedTrap, WhipKnot, and Loop-in-Loop did not damage the tendon during cyclic loading. SpeedTrap and Krackow had the least displacement. FiberLoop displaced more than all other groups (P= .016). No WhipKnot completed cyclic loading. The SpeedTrap (437N) and FiberLoop (413N) had the highest ultimate strength. While the SpeedTrap and FiberLoop are the strongest techniques, the FiberLoop shreds the tendon, displaced the most, and took longer to create. Based on these results, the SpeedTrap demonstrates the best overall performance.

All-Suture Anchors: Biomechanical Analysis of Pullout Strength, Displacement, and Failure Mode

To evaluate the biomechanical and design characteristics of all-suture anchors. All-suture anchors were tested in fresh porcine cortical bone and biphasic polyurethane foam blocks by cyclic loading (10-100N for 200 cycles), followed by destructive testing parallel to the insertion axis at 12.5mm/s. Endpoints included ultimate failure load, displacement at 100 and 200 cycles, stiffness, and failure mode. Anchors tested included JuggerKnot (1.4, 1.5, and 2.8), Iconix (1, 2, and 3), Y-knot (1.3, 1.8, and 2.8), Q-Fix (1.8 and 2.8), and Draw Tight (1.8 and 3.2). The mean ultimate failure strength of the triple-loaded anchors (564 ± 42N) was significantly greater than the mean ultimate failure strength of the double-loaded anchors (465 ± 33N)(P= .017), and the double-loaded anchors were stronger than the single-loaded anchors (256 ± 35N)(P < .0001). No difference was found between the results in porcine bone and biphasic polyurethane foam. None of these anchors demonstrated 5mm or 10mm of displacement during cyclic loading. The Y-Knot demonstrated greater displacement than the JuggerKnot and Q-Fix (P= .025) but not the Iconix and Draw Tight (P > .05). The most common failure mode varied and was suture breaking for the Q-Fix (97%), JuggerKnot (81%), and Iconix anchors (58%), anchor pullout with the Draw Tight (76%), whereas the Y-Knot was 50% suture breaking and 50% anchor pullout. The ultimate failure load of an all-suture anchor is correlated directly with its number of sutures. With cyclic loading, the Y-Knot demonstrated greater displacement than the JuggerKnot and Q-Fix but not the Iconix and Draw Tight. JuggerKnot (81%) and Q-Fix (97%) anchors failed by suture breaking, whereas the Draw Tight anchor failed by anchor pullout (76%). All-suture anchors vary in strength and performance, and these factors may influence clinical success. Biphasic polyurethane foam is a validated model for suture anchor testing.

A comparison of lateral ankle ligament suture anchor strength

Lateral ankle ligament repairs increasingly use suture anchors instead of bone tunnels. Our purpose was to compare the biomechanical properties of a knotted and knotless suture anchor appropriate for a lateral ankle ligament reconstruction. In porcine distal fibulae, 10 samples of 2 different PEEK anchors were inserted. The attached sutures were cyclically loaded between 10N and 60N for 200 cycles. A destructive pull was performed and failure loads, cyclic displacement, stiffness, and failure mode recorded. PushLock 2.5 anchors failed before 200 cycles. PushLock 100 cycle displacement was less than Morphix 2.5 displacement (p<0.001). Ultimate failure load for anchors completing 200 cycles was 86.5N (PushLock) and 252.1N (Morphix) (p<0.05). The failure mode was suture breaking for all PushLocks while the Morphix failed equally by anchor breaking and suture breakage. The knotted Morphix demonstrated more displacement and greater failure strength than the knotless PushLock. The PushLock failed consistently with suture breaking. The Morphix anchor failed both by anchor breaking and by suture breaking.

Impact to Spinal Cord Stimulator Lead Integrity with Direct Suture Loop Ties

Lead migration of spinal cord stimulators (SCS) is a significant problem, and experience suggests that anchoring sutures directly around the SCS lead may reduce migration. Such practices have been limited by concerns about potential damage to the lead and impairment of performance. This study sought to determine the extent of overt damage following maximal tension from tying sutures directly around SCS leads. Twenty-eight SCS leads were prospectively exposed to 56 suture knots that were tightened under controlled conditions to the suture's breaking point. Lead damage was evaluated by high power microscopy and assessment of lead impedance. None of the leads had evidence of substantial physical damage or electrical impairment. This small study suggests that anchoring directly to the lead appears to produce minimal damage, but these preliminary data must be confirmed and expanded.

The Effect of Saliva and Oral Intake on the Tensile Properties of Sutures

The plastic surgeon often operates in the oral cavity. Little or no information exists regarding the effect of saliva and oral intake upon the tensile properties of suture. Polyglactin 910 (Vicryl) and chromic gut were studied. Five sutures of each type were subjected to saline, saliva, milk, or soy milk over different durations of exposure. Suture breaking strength was tested. A 4-way interaction between suture type, size, liquid, and time was significant (P = 0.0046). Sutures soaked in saliva were significantly weaker. No significant difference was observed between sutures soaked in milk or soy. Saliva appears to enhance degradation rates in both sutures. Suture selection in the oral cavity should be predicated upon the demands of the repair and surgeon's preference. Postoperative feeding instructions should limit tension across mucosal repairs, but the selection of formula should be based upon nutritional requirements and preferences of the child rather than concern over suture degradation.

An In Vitro Biomechanical Comparison of the Breaking Strength and Stiffness of Polydioxanone (Sizes 2, 7) and Polyglactin 910 (Sizes 3, 6) in the Equine Linea Alba

To determine failure strength, stiffness, and failure mode of 4 suture materials in equine linea alba. Randomized complete block design. Linea albas collected from 12 adult horses (mean weight, 475 kg; mean age, 10 years). The ventral abdominal fascia, including the linea alba, was collected and bisected along the linea alba into right and left halves. Each half was divided into four, 5-cm sections extending from the umbilicus cranially, and randomly assigned to 1 of 4 suture materials: 2 polydioxanone (2 PD), 3 polyglactin 910 (3 PG), 6 polyglactin 910 (6 PG), and 7 polydioxanone (7 PD). A single cycle to failure test was performed on each specimen at a distraction rate of 100 mm/min. Differences in failure strength and stiffness for the materials were evaluated using a mixed linear model with significance set at P<.05. In 94 of 96 test sections, constructs failed by suture failure. There were significant differences in failure strength (P<.0001) and stiffness (P<.001) among the suture/tissue constructs. 7 PD had the highest breaking strength (316.8 N) followed by 6 PG (281.3 N), 3 PG (229.9 N), and 2 PD (193.0 N). Six PG had the largest stiffness (14 N/mm) followed by 3 PG (12.7 N/mm), 7 PD (10.1 N/mm), and 2 PD (7.2 N/mm). Suture breaking strength and stiffness were not affected by linea or fascia thickness, individual horse, half of the linea alba, or abdominal wall position. Eighty-five (90.4%) suture loops failed adjacent the knot. When tested in single cycle to failure, suture material was more likely to fail than the linea alba. Larger suture materials had higher breaking strengths than smaller suture materials and stiffness was also affected by suture material and size. Given its high initial breaking strength and its relatively longer in vivo strength retention, 7 PD seems an appropriate choice of suture material for closure of the equine linea alba when maximal short-term failure strength is desired.

Load to failure testing of new meniscal repair devices

Purpose: New all-inside meniscal repair devices include those combining sutures with anchors and that allow for an “adjustable” repair. This study’s purpose was to compare the failure strength of new meniscal repair devices with suture repairs. Type of Study: Experimental laboratory biomechanical study. Methods: A single repair was placed in a vertical longitudinal peripheral tear made in fresh adult porcine menisci. Group 1 had a vertically oriented suture using the FasT-Fix (Smith & Nephew Endoscopy, Andover, MA) device. Group 2 had a horizontally oriented mattress suture using the FasT-Fix device. Group 3 had a repair using 2 Arthrex (Naples, FL) meniscal darts. The Group 4 repair used a RapidLoc (Mitek Surgical Products, Westwood, MA) device. The Group 5 repair used the Arthrotek meniscal screw (Biomet, Warsaw, IN). Group 6 had a single vertical suture, and group 7 a single horizontal suture, both of 2-0 Mersilene (Ethicon, Somerville, NJ). Load to failure testing was performed. Results: The vertical FasT-Fix suture had a mean load to failure of 70.9 N (1 SD ± 33). The horizontal FasT-Fix suture had a mean load to failure of 72.1 N (± 23.5). The double Dart repair had a mean load to failure of 61.7 N (± 19). The RapidLoc repair had a mean load to failure of 43.28 N (± 3.98). The Arthrotek meniscal screw repair had a mean load to failure of 28.09 N (± 7.93). Failure occurred with device pullout of the inner rim (9 of 10) for the Darts, device pullout of the inner rim (6 of 10) and pullout of the outer rim (4 of 10) for the Arthrotek screw, and suture breakage for the FasT-Fix and the RapidLoc devices. The vertical sutures’ mean load to failure was 80.43 N (± 8.5), and all 13 failed by suture breaking. The horizontal sutures’ mean failure load was 55.9 N (± 18.8), and failure was by both suture breaking (6 of 10) and pulling through the meniscal tissue (4 of 10). Conclusions: Some of the newer meniscal repair devices show improved loads to failure over earlier generations.

Controlling the mechanical properties of poly(L‐lactide– ε‐caprolactone) monofilament sutures by an acetone/water treatment

AbstractFor monofilament biodegradable sutures fabricated from the L‐lactide–ε‐caprolactone (75/25) copolymer [P(LLA/CL)], there have been some concerns regarding their mechanical properties, such as the knot‐pull strength and stiffness. This article demonstrates the further potentiality of these sutures through improvements in those properties. With the aim of diminishing the molecular orientation, particularly in the suture surface region, we adopted an expedient method to treat P(LLA/CL) sutures with an acetone/water mixture, using different times and time patterns. The changes in the molecular orientation distributions across the suture cross sections were characterized by the specific index of birefringence measured with an interference microscope. The crystal orientations, knot‐pull strengths, tensile strengths, and bending rigidity were measured. The conformational changes in suture breaking during knot‐pull tests were analyzed with high‐speed‐video observations. Morphological analyses of the fractural surfaces were performed with scanning electron microscopy. The knot‐pull strength tended to rise, in comparison with that of untreated samples, up to a certain treatment time and was accompanied by a minimal decrement of the tensile strength. The knot‐pull strength did not show an increasing trend with further treatment, whereas the tensile strength declined remarkably. The birefringence, crystal orientation, bending rigidity, fractured surface analysis, and high‐speed‐video observations revealed molecular disorientation mainly in the filament outer layers for that particular treatment causing the sutures to be considerably softer. The suture softness played a role in changing the deformation behavior of the knot when a load was applied and caused the knot‐pull strength to rise. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2449–2462, 2002

TENSILE STRENGTH OF CADAVERIC FASCIA LATA COMPARED TO SMALL INTESTINAL SUBMUCOSA USING SUTURE PULL THROUGH ANALYSIS

The modified pubovaginal sling has become popular as first line treatment for stress urinary incontinence. With the increasing use of cadaveric fascia as a sling material, widespread shortages are prevalent, hence limiting its availability. The increased morbidity with the use of synthetic sling materials and autologous fascia has stimulated investigation of other sling materials. We evaluated the tensile strength of 4 suture types, and compared tensile strength of cadaveric fascia lata to porcine small intestinal submucosa using suture pull through analysis to assess their efficacy and durability for use in anti-incontinence procedures. Suture breaking load was determined using 2 and 1-zero polypropylene suture, and 2 and 1-zero polyglactin suture. Freeze dried gamma irradiated human fascia lata and freeze-dried small intestinal submucosa were evaluated. Suture was fixed to sling material using the cross fold technique. Mean suture breakage and suture pull through were determined using a tensionometer by measuring the load applied to the sling/suture system. Statistical analysis was performed. Mean suture breakage load was greatest with 1-zero polyglactin (8.10 pounds) and least with 2-zero polypropylene (3.68 pounds). Mean suture breakage strength was similar for 1-zero polypropylene and 2-zero polyglactin at 5.26 and 5.40 pounds, respectively. Mean suture pull through load using 1-zero polypropylene suture and the cross fold technique was 5.64 pounds for cadaveric fascia and 2.74 pounds for small intestinal submucosa (p <0.0001). Maximum load was limited by the suture strength when using cadaveric fascia, whereas, maximum load was limited in small intestinal submucosa by its inherent tensile strength. However, using a new technique for suture fixation to the small intestinal submucosa, we were able to increase significantly mean suture pull through load to 3.36 pounds (p = 0.008). Additionally, with this new technique small intestinal submucosa allowed gross stretching before suture pull through that was not seen with cadaveric fascia. Despite the current standard use of 1-zero polypropylene suture for pubovaginal sling fixation, our data suggest that 1-zero polyglactin suture is the strongest, and its use with pubovaginal sling fixation warrants further investigation. Using the cross fold technique and 1-zero polypropylene suture, tensile strength was greatest with cadaveric fascia compared to small intestinal submucosa. Although small intestinal submucosa was not as strong as cadaveric fascia, our persuasive preliminary data suggest that further investigation is warranted in the use of small intestinal submucosa and other suture fixation techniques, and its observed stretch capacity. Hence, with further studies small intestinal submucosa may remain a viable option for pubovaginal sling material.

New atraumatic rounded-edge surgical needle holder jaws

A new atraumatic smooth needle holder jaw with rounded edges that does not damage synthetic monofilament sutures is described herein. These rounded edges were created by mechanical filing of the sharp edges of smooth needle jaws. Compression of the monofilament suture between the needle holder jaw with sharp edges reduces the suture breaking strength compared with that of control sutures. A quality control method has been devised to detect the potentially damaging sharp edges of smooth needle jaws that can be easily implemented by needle holder manufacturers.

The burst abdominal wound: a mechanical approach.

The burst abdominal wound has a mechanical cause. It is the results of suture breaking, knot slipping, the intact suture cutting out of the tissues or protrusion of gut or omentum between stitches. Measurements of abdominal girth and the xiphoid-pubis distance before and during abdominal distension show that a wound may lengthen by 30 per cent if distension occurs. An adequate reserve of suture length in the wound is necessary to allow this lengthening to occur and to ensure a minimal resulting rise in tension between the sutures and the tissues. Three variables present in every continuous wound closure--the suture length inserted, the wound fasical length and the number of stitches--determine the stitch interval and the size of the tissue bite, which are the two vital factors in wound strength under the surgeon's control. These variables may be expressed by the ratio of the length of suture (SL) inserted to the wound length (WL), the ratio SL:WL. Analytical and clinical evidence is presented to show that: 1. Deep wound disruption (evisceration and ventral hernia) is associated with the use of an SL: WL ratio of 2: 1 or less-the lower the ratio, the greater is the risk of a burst wound. 2. Wound disruption because of cutting out of sutures can be prevented by the use of non-absorbable continuous sutures at 1-cm intervals and an SL:WL ratio of 4:1 or more.