What is the Best Surgeon's Knot? Evaluation of the Security of the Different Laparoscopic Knot Combinations

Knot Security 101: A Comprehensive Practical Review to Optimal Knot Configuration, Pulling Direction, Throw Count, and Tail Length

Background

Knots are the weakest structural point in a suture line and inevitably weaken almost all suture materials. This practical review critically evaluates the factors, such as suture material properties, gauge, configuration, throw count, and tail length, that affect knot security.

Methods

A PubMed search between the years 1934 and 2023 identified relevant studies that addressed factors relating to knot security. Studies that investigated knots and sutures solely used in laparoscopic and arthroscopic surgery were excluded. Knot configurations assessed were the Aberdeen, sliding, square, and surgeon's.

Results

Eighty-six articles were included in this review article and demonstrated that knot security varies greatly between suture materials and gauge. Knot security also varies by configuration, throw count, conditions, tail length, and stitch type. Throw count differs by knot configuration, with the Aberdeen knot being most secure with three throws and one to two turns compared with three to five throws for surgeon's and square knots. The optimal tail length was 3 mm.

Conclusions

This practical review demonstrates that there are significant differences in knot security based on a variety of factors. It is challenging to propose an ideal knot because most studies did not evaluate knot security using a broad variety of suture materials, gauges, and throws for each of the most common knots. Although this review article demonstrated several applicable findings, additional robust studies are needed to simplify proposals.

The importance of rotation to teach secure half-hitch sequences in surgery

Background

Knot security of half-knot (H) sequences varies with rotation, but half-knots risk destabilisation.

Objectives

To investigate the rotation of half-hitch (S) sequences on knot security.

Materials and Methods

The loop and knot security of symmetrical and asymmetrical sliding and blocking half-hitch sequences was measured using a tensiometer.

Results

Loop security of symmetrical sliding half-hitch sequences is much higher than asymmetrical sequences, increasing from 6+2 to 21+2 and from 27+6 to 48+5 Newton (N) for 2 and 4 half-hitches respectively (both P<0.0001). Symmetrical sliding sequences are more compact and remain in the same plane, squeezing the passive thread, while asymmetrical sequences rotate loosely around the passive end. Blocking sequences are superior when asymmetrical since changing the passive end acts like changing rotation, transforming the asymmetrical sliding into a symmetrical blocking half-hitch on the new passive thread. The knot security of 2 sliding and 1 blocking half-hitch doubles from 52+3 to 98+2 N for the worst (asymmetric sliding and symmetric blocking, SSaSsb) or best rotation sequences (SSsSab). Adding a second asymmetric blocking half-hitch (Sab) increases security further to 105+3 N. The overall knot security of four-throw, correctly rotated, half-hitch (SSsSabSab) or half-knot (H2H1sH1s, H2H2a and H2H2s) sequences is similar for four suture diameters.

Conclusion

Rotation affects the security of half-hitch sequences, which should be symmetrical when sliding, and asymmetrical when blocking.

What is new?

Half-hitch sequences are clinically superior to half-knot sequences. They do not risk destabilisation, and loop security improves approximation of tissues under traction, permitting tight knots.

Assessing Endoscopic Suture Performance of Gynecology and Obstetrics Residents Following Methodic Training

OBJECTIVE

 To evaluate the performance of residents in gynecology and obstetrics before and after practicing laparoscopic sutures, to establish when the training shows the best results, in addition to comparing whether being in different years of residency influences this progression.

METHODS

 A prospective cohort study involving 32 medical residents evaluated with a pretest to establish their previous knowledge in laparoscopic suture. This test consisted of knotting two wires, one made of polypropylene and the other of polyglactin, with a blocking sequence of five semi-knots. We set a 30-minute limit to complete the task. Then, the residents held four training meetings, focusing on suture, Gladiator rule, knot, and symmetries, in addition to executing blocking sequences. A second test to establish progress was performed.

RESULTS

 Regarding the time spent to make the stiches using polyglactin wire, a statistically significant time improvement (p < 0.01) was observed, with a 10.67-minute pretraining median (mean 12.24 minutes) and a 2.53-minute posttraining median (mean 3.25 minutes). Regarding the stitches with polypropylene wire, a statistically significant time improvement (p < 0.05) was also observed, with a 9.38-minute pretraining median (mean 15.43 minutes) and a 3.65-minute posttraining median (mean 4.54 minutes). A total of 64.2% of the residents had been able to make the knot with polypropylene previously. One hundred percent were able to complete the task in the posttest.

CONCLUSION

 Model training using the Gladiator rule for laparoscopic suture improves the knotting time with statistically similar performance, regardless of the year of residency, after systematic training.

Laparoscopic Surgery: A Systematic Review of Loop and Knot Security, Varying with the Suture and Sequences, Throws, Rotation and Destabilization of Half-Knots or Half-Hitches

Surgical knots are sequences of half-knots (H) or half-hitches (S), defined by their number of throws, by an opposite or similar rotation compared with the previous one, and for half-hitches whether they are sliding (s) or blocking (b). Opposite rotation results in (more secure) symmetric (s) knots, similar rotation in asymmetric (a) knots, and changing the active and passive ends has the same effect as changing the rotation. Loop security is the force to keep tissue together after a first half-knot or sliding half-hitches. With polyfilament sutures, H2, H3, SSs, and SSsSsSs have a loop security of 10, 18, 28, and 48 Newton (N), respectively. With monofilament sutures, they are only 7, 16, 18, and 25 N. Since many knots can reorganize, the definition of knot security as the force at which the knot opens or the suture breaks should be replaced by the clinically more relevant percentage of clinically dangerous and insecure knots. Secure knots with polyfilament sutures require a minimum of four or five throws, but the risk of destabilization is high. With monofilament sutures, only two symmetric+4 asymmetric blocking half-hitches are secure. In conclusion, in gynecology and in open and laparoscopic surgery, half-hitch sequences are recommended because they are mandatory for monofilament sutures, adding flexibility for loop security with less risk of destabilization.

Does quality of novice hand-tied square knots improve with repetition during a single training session?

Background

Knot tying is a key surgical skill for novices, and repetition over several training sessions improves knot tying. This study examined the effects of repetition within a single training session on quality of knotted loops and compared results of novice trainees and experienced surgeons.

Methods

Using 0.55 mm nylon monofilament fishing line, novices and surgeons each hand-tied 20 knotted loops, using a 2=1=1=1 configuration (surgeon's throw and three square throws). Loops were mechanically tested with a single load to failure.

Results

All loops tolerated five newtons (N) preload. More than 70% of novice and surgeon knots failed by slipping or untying, and 8.8% of novice knots and 2.5% of surgeon's knots were considered dangerous. Surgeons' loops had less extension at preload, indicating better loop security. However, during single test to failure, there was no difference in mean extension or maximum load between surgeons and novices. There was no significant difference in results of mechanical testing or modes of failure for the first and last ten knotted loops, or the first, second, third, and fourth sets of knotted loops.

Discussion

With appropriate training, novices can construct knots as strong and secure as experienced surgeons. A large percentage of knotted loops are insecure under testing conditions; extra throws may be required when using large diameter monofilament nylon. Novices may require extra training in maintenance of loop security when constructing square knots. Tying more than five or 10 knotted loops within a single training session does not provide added benefits for novices.

Technical features, perioperative and anatomical outcomes of a standardized suturing pattern for robotic sacrocolpopexy

INTRODUCTION AND HYPOTHESIS

Several technical alternatives to repair mesh using laparoscopic sacrocolpopexy exist. We aim to describe the outcomes and surgical technique of robotic-assisted colpo-/cervicosacropexy using a standardized suturing scheme to repair the mesh.

METHODS

We retrospectively reported data of 60 consecutive cases of robotic-assisted colpo-/cervicosacropexy for advanced multicompartmental prolapse using a standardized suturing design. We placed three non-absorbable stitches on the cervix or three absorbable stitches on the apex of the vaginal vault, six long-term absorbable stitches on the anterior vaginal wall deep to the basis of the vesical trigone, six similar posterior stitches with the deeper row of sutures down to the levator ani plane and three non-absorbable stitches on the sacral promontory as the cranial support for Y-shaped polypropylene mesh.

RESULTS

Median operative time was 188 ± 43 min. All the procedures were successfully performed using a Da Vinci Si platform in a three-arm configuration, and no conversion to open or traditional laparoscopic surgery was needed. The length of hospital stay was 1.2 ± 1.7 days, and no readmission within 30 postoperative days was reported. At a follow-up of 12 and 24 months, no case of extrusion or exposure of the mesh occurred, and the retreatment rate was 6.7%.

CONCLUSIONS

Our suturing technique is safe and effective, with negligible risk of complications and good medium-term results. It is plausible that robotic systems may facilitate precise, accurate and reproducible placement of the stitches, thereby favoring wider diffusion of minimally invasive treatment of advanced prolapse.

Optimization of the knot configuration for early accelerated rehabilitation after Achilles tendon rupture

Background Panda Rope Bridge Technique (PRBT) was an new minimally invasive technique consisted of two bridge anchors (proximal anchors at calcaneus and distal anchors at myotendinous junction) and strong ropes (threads of the suture anchors) stretched between them, which was suitable for early accelerated rehabilitation of Achilles tendon rupture. However, the optimal knot configuration with PRBT was unknow. The purpose of this study was identify minimum number of half hitches necessary to maintain knot security for PRBT. Methods Using an Instron device we tested the effect of different knot configuration in two kinds of suture threads (Ethibond™ #5 and Ultrabraid™ #2). According to the result of it, we put the optimal knot configuration into Part 1 with PRBT test model and Part 2 with modified PRBT test model, to evaluate whether the optimal knot configuration could complete the cyclic loading test simulated early rehabilitation. Findings In the first part of the study, the optimal knot configuration of Ethibond™ #5 suture thread was the combination of three half hitches and one double throw half knot, and the optimal knot configuration of Ultrabraid™ #2 suture thread was the combination of five half hitches and one double throw half knot. In the second part of the study, only Ultrabraid™ #2 suture thread with optimal knot configuration had finished all test in Part 1. Interpretation The Ultrabraid™ #2 suture thread with optimal knot configuration was suitable for PRBT with early accelerated rehabilitation after Achilles tendon repair.

In vitro holding strength of the laparoscopic Miller's knot compared with open Miller's knot, open surgeon's throw, and laparoscopic surgeon's throw in a vascular pedicle model

OBJECTIVE

To compare in vitro knot holding strength of the laparoscopic Miller's knot (LMK), open Miller's knot (MK), open surgeon's throw (Sx), and laparoscopic surgeon's throw (LSx) in a vascular pedicle model when used as the first throw for vascular ligation.

STUDY DESIGN

Experimental study.

SAMPLE POPULATION

Ten constructs each of the Miller's knot and surgeon's throw performed openly and laparoscopically with 2-0 polyglyconate suture.

METHODS

Knot holding strengths of the LMK, MK, LSx, and Sx knots were evaluated on balloon dilation catheters used as vascular pedicle models. Laparoscopic knots were tied in a laparoscopic box trainer. Knot constructs were pressure tested to failure. Results were compared by Kruskal-Wallis and Steel-Dwass comparisons.

RESULTS

Both MK and LMK had mean leakage pressures above 300 mm Hg. The MK leaked at higher pressure than all other knots, including the LMK (P < .001). The LMK leaked at greater pressures compared with the Sx and the LSx (P < .001). No difference was detected between leaking pressures of the Sx and the LSx (P = .226), with both leaking at pressures below 40 mm Hg.

CONCLUSION

The LMK created a more secure first throw compared with the Sx and leaked at supraphysiologic pressures.

CLINICAL SIGNIFICANCE

The LMK has excellent knot holding strength on a vascular pedicle model and may be further evaluated for clinical application.

Combined Laparoscopic-Hysteroscopic Isthmoplasty Using the Rendez-vous Technique Guided Step by Step

OBJECTIVE

To demonstrate the surgical technique of Rendez-vous isthmoplasty for the treatment of symptomatic cesarean scar defect. In this video, the authors show the complete procedure in a step-by-step manner to standardize and facilitate the comprehension and performance of the procedure in a simple and safe way.

DESIGN

Step-by-step video demonstration of the surgical technique.

SETTING

Private hospital in Curitiba, Paraná, Brazil.

INTERVENTIONS

The patient is a 36-year-old woman without any comorbidities, G3 C3, and with radiologic transvaginal ultrasound diagnosis of isthmocele grade 3 (over 25 mm) identified in the superior third of the cervical canal. The main steps of combined laparoscopic-hysteroscopic isthmoplasty using the Rendez-vous technique are described in detail. A combined laparoscopic-hysteroscopic approach was performed. Under general anesthesia, the patient was placed in 0° supine decubitus, with her arms alongside her body. Operative setup included 15 mm Hg pneumoperitoneum, created using the closed Veress technique, and 4 trocars: a 10-mm trocar at the umbilicus for a 0° laparoscope, a 5-mm trocar in the right iliac fossa, a 5-mm trocar in the left iliac fossa, and a 5-mm trocar in the suprapubic area. The procedure begins after a systematic exploration of the pelvic and abdominal cavities. Step 1: Identification of key anatomic landmarks and exposure of the operation field. Step 2: By carrying out blunt and sharp dissection with cold scissors or a harmonic scalpel, the visceral peritoneal layer over the isthmus area is opened, a vesicouterine space is developed, and the bladder is pushed down at least 2 cm from the lower edge of the isthmocele. Step 3: Final Phrase: By hysteroscopic exploration of the cervical canal using the vaginoscopic approach, identification and delimitation of the isthmocele its performed by recognizing the diverticular mucosal hyperplasia, and then the hysteroscopic light is pointed directly toward the cephalic limit of the scar defect. Step 4: Laparoscopic lights are decreased in intensity and the "Halloween sign" is identified (hysteroscopic transillumination). The light of the hysteroscope is pointed to the top of the cesarean scar defect allowing the laparoscopist to identify the upper and lower edges of the scar. Step 5: Laparoscopic resection of all scar tissue, excision of all the edges of the pseudo cavity. Step 6: Adequate intracorporeal suturing technique, with a 2-layer myometrial repair using intracorporeal running and interrupted stitches of polydioxanone 2-0, is done, while ensuring preservation of the cavity by not including the endometrial tissue in the myometrial suture [1-3]. Step 7: Installation of the methylene blue dye to locate any leakage. The surgery ended without any intraoperative complications and within 60 minutes. The patient was discharged on the first day postoperatively and became pregnant 6 months after surgery, with a final C-section delivery of a healthy term newborn at 39-weeks gestational age.

CONCLUSION

Combined Rendez-vous isthmoplasty is feasible, safe, and effective in experienced hands, giving the surgeon a comprehensive evaluation of the anatomy of the isthmocele, and increasing the odds of a complete resection and restoration of the anatomy [4-7]. In this patient, the procedure was uneventful, without any intra- or postoperative complications, and the symptoms were completely controlled.

The Role of Deconstructive Teaching in the Training of Laparoscopy

Background and Objectives

Skills-lab training is crucial for the development of advanced laparoscopic skills. In this study, we examined whether a systematic deconstructive and comprehensive tutoring approach improves training results in laparoscopic suturing and intracorporeal knot tying.

Methods

Sixteen residents in obstetrics and gynecology participating in structured skills-lab laparoscopy training were randomized in 2 equal-sized groups receiving 1-on-1 tutoring either in the traditional method or according to the Peyton's 4-step approach, involving an additional training step, with the trainees instructing the tutor to perform the exercises. A validated assessment tool (revised Objective Structured Assessment of Technical Skills) and the number of completed square knots per training session and the mean time per knot were used to assess the efficacy of training in both groups.

Results

Trainees in Peyton's group achieved significantly higher revised Objective Structured Assessment of Technical Skills scores (28.6 vs 23.9 points; P = .05) and were able to improve their scores during autonomous training repetitions, in contrast to the trainees not in Peyton's group (difference +4.75 vs -4.29 points, P = .02). Additionally, they seemed to be able to perform a greater number of successful knots during the exercise and to complete each knot quicker with the later observations failing to reach the threshold of statistical significance.

Conclusion

Peyton's 4-step approach seemed to be superior for teaching laparoscopic skills to obstetrics and gynecology residents in the skills-lab setting and can be therefore proposed for training curricula.