Tension of knotted surgical sutures shows tissue specific rapid loss in a rodent model

Impact of small-bite (5 mm) fascial closure on the incidence of incisional hernia following open colorectal cancer surgery: randomized clinical trial

BACKGROUND

Incisional hernia is frequently observed after open colorectal cancer surgery, and should be considered a serious short- and long-term health issue. The present study evaluated the efficacy of small-bite abdominal closure in reducing the incidence of incisional hernia in this patient group.

METHODS

An RCT was conducted between June 2019 and June 2022. A total of 173 patients who underwent open colorectal cancer surgery were assigned randomly to one of two groups to undergo fascial closure with either small bites (87) or conventional bites (86). The incisional hernia rate was accepted as the primary outcome, and surgical-site infection as the secondary outcome.

RESULTS

The incisional hernia rates at 1 year were 7 and 27% in the small- and conventional-bite groups respectively (P < 0.001). This rate increased to 9 and 31% at the end of the second year (P < 0.001). Surgical-site infections occurred in 18% of the small-bite group and 31% of the conventional-bite group (P = 0.03). Compared with the conventional-bite group, the small-bite group had higher suture/wound length ratios (mean(s.d.) 5.18(0.84) versus 3.67(0.57); P < 0.001) and a longer fascial closure time 14.1(4.64) versus 12.9(2.39) min; P = 0.03).

CONCLUSION

Small-bite closure with 5-mm tissue bites placed 5 mm apart reduced the incidence of incisional hernia and surgical-site infection after open colorectal cancer surgery.

Effects of Real Time Feedback on Novice's Laparoscopic Learning Curve

OBJECTIVE

Analyze the learning curve of medical students when they are trained with a laparoscopic box trainer and are presented with different modes of real-time feedback on their performance in the laparoscopic suturing procedure.

DESIGN

A prospective randomized controlled trial (RTC) was performed. Three groups were proposed: control, visual, and haptic. The block randomization technique was used to assign the participants to one of the three groups. Each group trained the intracorporeal square flat knot task in a standardized FLS box simulator. A total of 11 sessions were programmed for this study: a pre-training session, eight training sessions, a post-training session, and a follow-up session. Measurement of the generated reaction force during the task were taken weekly for the first 10 sessions (pre-training, training, and post-training); then, the follow-up measurement was taken a month after.

SETTING

This study was carried out in a single center at the Unidad de Simulación de Posgrado (USIP) of the postgraduate medicine program of the Universidad Nacional Autónoma de México (UNAM) between May and August 2023.

PARTICIPANTS

The eligible participants were medical students without experience in minimally invasive surgery. All social service intern medics doing their social service in the USIP were invited to participate. A total of 20 participants entered the study from which 18 of them finished all the programmed sessions.

RESULTS

A total of ten metrics were extracted from the reaction force signal measured at each session. All metrics are directly proportional to the reaction force and low magnitudes imply high tissue-handling proficiency. All groups improved their tissue handling skills, being the visual group the one who achieved better performance, followed by the haptic group and lastly the control group.

CONCLUSION

The use of real time feedback, especially visual feedback can help novices to shorten the learning process of tissue handling and achieve a better proficiency in advanced tasks in shorter training periods.

Early Experience with Mesh Suture for DIEP Flap Abdominal Site Closures

Background

The gold standard of microsurgical breast reconstruction is the deep inferior epigastric perforator (DIEP) free flap. As techniques have evolved, DIEP flaps have significantly reduced the morbidity previously caused by transverse rectus abdominis muscle (TRAM) and muscle-sparing TRAM flaps. However, abdominal wall complications continue to persist after DIEP flap surgery, with bulge rates reported as high as 33%.

Methods

The first 25 patients undergoing DIEP flap surgery with the use of Duramesh (MSI, Chicago, Ill.) by the senior author were identified. A retrospective chart review of patient and surgical details was performed. Charts were reviewed for outcomes, including surgical site infections, surgical site events, incisional hernia formation, and/or bulge. Standard descriptive summary statistics were used for patient characteristics, surgical details, and primary and secondary outcomes.

Results

Twenty-five patients were reviewed. Average follow-up duration was 216 ± 39 days. One patient (4%) developed a surgical site infection, and four patients (16%) developed a surgical site event. One patient developed a bulge, but no patients developed an incisional hernia.

Conclusions

Duramesh mesh suture provides a promising opportunity for DIEP surgeons to minimize both abdominal wall morbidity and mesh-related complications. Mesh suture can be used in a similar fashion as other sutures to perform primary closure of the anterior rectus sheath while also providing force-distribution benefits typically unique to planar mesh. This pilot study suggests that Duramesh is a safe, simple alternative to existing techniques in DIEP flap surgery and can be considered by microsurgeons to reduce fascial dehiscence, bulge, and/or hernia formation.

Suture Characteristics after Exposure to Amniotic Fluid from an in vitro Model of Fetal Surgery

INTRODUCTION

Suture tensile properties have only been tested in extrauterine environments. Amniotic fluid (AF) is a complex milieu of enzymes and inflammatory factors. This study tested the mechanical properties of sutures with a variety of inherent properties, after exposure to AF from patients with conditions prompting fetal intervention.

METHODS

AF was obtained from 3 patients with twin-twin transfusion syndrome (TTTS), and 3 patients with neural tube defects. Six types of 2-0 sutures were placed on 1.2 N of tension to mimic placement in vivo, and incubated in AF at 37°C (98.6°F). These included ethylene terephthalate (Ethibond), glycomer 631 (V-Loc), poliglecaprone 25 (Monocryl), poly-4-hydroxybutyrate (Monomax), polydioxanone (PDS), and polyglactin 910 (Vicryl). Failure load, stress, strain, and initial modulus were tested after 24 h of incubation and after 4 weeks, and compared with control (unincubated) sutures using t tests, Kruskal-Wallis tests, and stress-strain curves.

RESULTS

Poliglecaprone 25 and polyglactin 910 dissolve more quickly in AF compared to outside the uterus, disintegrating at 4 weeks. Ethylene terephthalate and PDS experienced little change across 4 weeks of incubation. Glycomer 631 and poly-4-hydroxybutyrate exhibited interesting behavior in AF: glycomer 631 became more deformable at 24 h but later regained toughness by 4 weeks, while poly-4-hydroxybutyrate became tougher and in some cases stronger with time in AF. As a class, braided sutures act more like rigid materials, and monofilaments act like deformable plastics.

CONCLUSION

These findings along with other suture characteristics such as ease of handling and availability may inform fetal intervention teams as they optimize procedures in a relatively new surgical field.

Developing and validating an implantable suture tension sensor

Introduction

Suture tension has a direct influence on the sutured tissue. For abdominal wall closure, suture tension should be optimal without causing tissue necrosis, which can result in surgical site infection or incisional hernia. The purpose of the present study is to evaluate a device that can measure suture tension in-situ and in real-time.

Materials and methods

A cheap, commercially available analog-to-digital converter was used, in conjunction with a force sensing resistor. A sensor probe housing was designed and 3D-printed. In order to test the sensor, a mechanical, computer controlled human abdominal wall model called the AbdoMAN was used.

Results

An implantable suture tension sensor was developed, keeping cost-effectiveness in mind. This sensor can translate tension in the suture into a downward force, applied to the force sensing resistor. The sensor's raw readout was characterized using a set of weights, from which a formula correlating the readout to a specific force, was derived. Preliminary validation was successfully performed using the AbdoMANmodel, which showed a progressive rise in suture tension when the intra-abdominal pressure was artificially increased over time.

Conclusion

The implantable suture tension sensor appeared to be capable of recording real time changes in suture tension, and the. validation process of this sensor has been initiated. With the information from devices like this, a much better understanding of the issues at play in the development of incisional hernia can be gained.

Duramesh registry study: short-term outcomes using mesh suture for abdominal wall closure

Introduction

Sutures are flexible linear elements that join tissue and maintain their hold with a surgeon-created knot. Tension at the suture/tissue interface can cut the very tissues that sutures are designed to hold, leading to dehiscence and incisional hernia formation. A new suture design (Duramesh, Mesh Suture Inc., Chicago, IL) was approved for marketing by the United States Food and Drug Administration in September 2022. The multiple filaments of the mesh suture are designed to diffuse tension at the suture/tissue interface thereby limiting pull-through. The macroporosity and hollow core of the mesh suture encourage fibrovascular incorporation for a durable repair. We created the first registry and clinical report of patients undergoing mesh suture implantation to assess its real-world effectiveness.

Methods

A patient registry was created based on institutional implant logs from January to August 2023 at an integrated health-care system. Operative reports were reviewed by the study team to verify use of "Duramesh" by dictation. Retrospective chart review was conducted to evaluate patient and surgical characteristics, follow-up, and short-term outcomes of interest. Results were analyzed using descriptive statistics and Chi-squared analysis with Microsoft Excel and GraphPad Prism.

Results

Three hundred seventy-nine separate implantations by 56 surgeons across 12 (sub) specialties at a university hospital and two community hospitals were performed. Mesh suture was used for treatment of the abdominal wall in 314 cases. Follow-up averaged 80.8 ± 52.4 days. The most common abdominal wall indications were ventral hernia repair (N = 97), fascial closure (N = 93), abdominal donor site closure from autologous breast reconstruction (N = 51), and umbilical hernia repair (N = 41). Mesh suture was used in all Centers for Disease Control (CDC) wound classifications, including 92 CDC class 2 or 3 abdominal operations. There were 19 surgical site infections (6.1%) and 37 surgical site events (11.8%).

Conclusions

Short-term registry data demonstrates the wide diversity of surgical disciplines and scenarios in which mesh suture has been used to date. The early adoption of mesh suture into practice highlights that consequences of suture pull-through influence operative decision making. As this is the first interim report of the Duramesh mesh suture registry, follow-up is too short for characterization of long-term durability of abdominal wall closures.

The Best Closure Technique Without Mesh in Elective Midline Laparotomy Closure

Introduction: The risk of developing an incisional hernia after primary elective median laparotomy is reported in the literature as being between 5 and 20 percent. The basic of an optimal outcome after midline incision is the appropriate closure technique with or without a prophylactic mesh. The objective of this paper is to critically examine the various closure techniques and, in particular, to present a detailed comparison of the long stitch and short stitch techniques. Method: Based on the available literature, the characteristics of the different closure techniques are described in detail, advantages and disadvantages are compared, and the current status of a practicable recommendation is discussed. Special attention is paid to the criteria of the short stitch technique, such as the suture to incision length ratio, number of stitches and distances, as well as suture material. Results: For elective midline closures, the use of a continuous closure using a slowly absorbable suture material in the small-bites technique with suture to wound ratio of at least 5:1 result in significantly lower risk of complications such as bursting abdomen and less incisional hernia rates compared to the large-bites technique. Conclusion: Based on the present evidence in midline closure after elective laparotomy the small bites technique can be recommended to significantly reduce the rate of incisional hernia.

Novel Elastic Threads for Intestinal Anastomoses: Feasibility and Mechanical Evaluation in a Porcine and Rabbit Model

Gastrointestinal anastomoses are an important source of postoperative complications. In particular, the ideal suturing material is still the subject of investigation. Therefore, this study aimed to evaluate a newly developed suturing material with elastic properties made from thermoplastic polyurethane (TPU); Polyvinylidene fluoride (PVDF) and TPU were tested in two different textures (round and a modified, “snowflake” structure) in 32 minipigs, with two anastomoses of the small intestine sutured 2 m apart. After 90 days, the anastomoses were evaluated for inflammation, the healing process, and foreign body reactions. A computer-assisted immunohistological analysis of staining for Ki67, CD68, smooth muscle actin (SMA), and Sirius red was performed using TissueFAXS. Additionally, the in vivo elastic properties of the material were assessed by measuring the suture tension in a rabbit model. Each suture was tested twice in three rabbits; No major surgical complications were observed and all anastomoses showed adequate wound healing. The Ki67+ count and SMA area differed between the groups (F (3, 66) = 5.884, p = 0.0013 and F (3, 56) = 6.880, p = 0.0005, respectively). In the TPU-snowflake material, the Ki67+ count was the lowest, while the SMA area provided the highest values. The CD68+ count and collagen I/III ratio did not differ between the groups (F (3, 69) = 2.646, p = 0.0558 and F (3, 54) = 0.496, p = 0.686, respectively). The suture tension measurements showed a significant reduction in suture tension loss for both the TPU threads; Suturing material made from TPU with elastic properties proved applicable for intestinal anastomoses in a porcine model. In addition, our results suggest a successful reduction in tissue incision and an overall suture tension homogenization.

Construct validity of the SurgForce system for objective assessment of laparoscopic suturing skills

BACKGROUND

Laparoscopic surgery requires a new set of skill to be learned by the surgeons, of which the most relevant is tissue manipulation. Excessive forces applied to the tissue can cause rupture during manipulation or ischemia when confronting both sides of the tissue. The aim of this study is to establish the construct validity of the SurgForce system for objective assessment of advanced laparoscopic skills, based on the force signal generated during suture tasks, and the development of force parameters for evaluating tissue handling interaction.

METHODS

The SurgForce system, a tissue handling training device that measures dynamic force, was used to capture the force generated by surgeons with different levels of laparoscopic experience. For construct validity, 37 participants were enrolled in this study: 19 medical students, 12 residents of surgical specialties and 6 expert surgeons. All participants performed an intracorporeal knotting suture task over a synthetic tissue pad with a laparoscopic box-trainer. The force performance of the participants was analyzed using 11 force-based parameters with the application of the SurgForce system. Statistical analysis was performed between novice, intermediate, and expert groups using a Kruskal-Wallis test, and between the pairs of groups using a Mann-Whitney U-test.

RESULTS

Overall, 9 of the 11 force-related parameters showed significant differences between the three study groups. Results between the pairs of groups presented significant differences in 5 force parameters proposed. Construct validity results demonstrated that the SurgForce system was able to differentiate force performance between surgeons with different levels of laparoscopic experience.

CONCLUSION

The SurgForce system was successfully validated. This force system showed its potential to measure the force exerted on tissue for objective assessment of tissue handling skills in suturing tasks. Furthermore, its compact design allows the use of this device in conventional laparoscopic box-trainers.

Design of a loading system for cyclic test on sutured organs

The design of loading systems to test biologic samples is often challenging, due to shape variability and non-conventional loading set-ups. In addition to this, large economic investments would not be justified since the loading set up is usually designed for one single or for a limited range of applications.

The object of this work is the development of a loading set-up finalised to on-site testing of sutures whose main function is applying a localised tensile load. The main challenges of this design process can be so summarized:•

Applying cyclic tensile loads on the suture wire, mimicking the physiologic condition where both suture anchorage points have a certain compliance;

•

Designing a loading system as versatile as possible, in order to be able to accommodate organs with different geometries and sizes;

•

Keeping low both the complexity and costs of realization.

All these considerations and the design calculi are here reported in detail, discussing the novelty of the system, and its main advantages.

Quantifying fascial tension in ventral hernia repair and component separation

BACKGROUND

Excessive fascial tension is a major cause of ventral hernia recurrence. Although hernias are commonly characterized by area, the tension experienced by fascia is directly proportional to the surrounding tissue stiffness. We demonstrate an accurate and simple technique for intra-operative measurement of fascial closing tension and quantify the decrease in tension following Component Separation (CS).

METHODS

A tensiometer was created using a spring with a known recoil constant (k) and a surgical clamp. Using Hooke's law (Force = kX; X = spring displacement), fascial tension was calculated. This method was first validated on a bench-top model and then applied to the anterior fascia of 4 fresh cadavers (8 hemi-abdomens) over a range of simulated hernia defect sizes. When fascia could no longer reach midline, CS was performed and measures repeated. Tissue stiffness was calculated by plotting defect size versus resulting tension.

RESULTS

Fascial defects ranged from 1- to 18-cm wide with average midline closing tension prior to release 36.1 N (range 17-48) and 8.2 N (range 5-11) after CS, a mean 76% decrease (range 70%-85%). Mean R2 values between defect size and tension for the synthetic and cadaver models were 0.99 (p < 0.01) and 0.91 (p = 0.01; all hemi-abdomen measurements significant). Inter-rater Pearson's correlation consistently found R² values > 0.95 (p < 0.01) for each hemi-abdomen, showing high precision and reproducibility.

CONCLUSION

We have applied a cheap, simple, and precise method to sterilely assess fascial tension during herniorrhaphy and also quantified the decrease in tension following component separation. This technique may be rapidly translated into the operating room with minimal equipment to provide objective data critical for intraoperative decision-making.

Securing split-thickness skin grafts using negative-pressure wound therapy without suture fixation

OBJECTIVE

Negative-pressure wound therapy (NPWT) is generally applied as a bolster for split-thickness skin grafts (STSG) after the graft has been secured with sutures or skin staples. In this study, NPWT was applied to secure STSGs without any sutures or staples. Surgical outcomes of using NPWT without sutures was compared with a control group.

METHODS

Patients with STSGs were divided into two groups: a 'no suture' group using only NPWT, and a control group using conventional fixings. In the no suture group, the grafts were covered with meshed wound dressing and ointment. The NPWT foam was placed over the STSG and negative pressure applied. In the control group, grafts were fixed in place using tie-over bolster, securing with fibrin glue, or NPWT after sutures.

RESULTS

A total of 30 patients with 35 graft sites participated in the study. The mean rate of graft take in the no suture group was 95.1%, compared with 93.3% in the control group, with no significant difference between them. No graft shearing occurred in the no suture group. Although the difference did not reach statistical significance, mean surgical time in the no suture group (31.5 minutes) tended to be shorter than that in the control group (55.7 minutes).

CONCLUSION

By eliminating sutures, the operation time tended to be shorter, suturing was avoided and suture removal was not required meaning that patients could avoid the pain associated with this procedure. Furthermore, the potential for staple retention and its associated complications was avoided, making this method potentially beneficial for both medical staff and patients.

Evaluation of a new suture material (Duramesh™) by measuring suture tension in small and large bites techniques for laparotomy closure in a porcine model

PURPOSE

After closure of laparotomies, sutures may pull through tissue due to too high intra-abdominal pressure or suture tension, resulting in burst abdomen and incisional hernia. The objective of this study was to measure the suture tension in small and large bites with a new suture material.

METHODS

Closure of the linea alba was performed with small bites (i.e., 5 mm between two consecutive stitches and 5 mm distance from the incision) and large bites (i.e., 10 mm × 10 mm) with Duramesh™ size 0 (2 mm) and PDS II 2-0 in 24 experiments on six porcine abdominal walls. The abdominal wall was fixated on an artificial computer-controlled insufflatable abdomen, known as the 'AbdoMan'. A custom-made suture tension sensor was placed in the middle of the incision.

RESULTS

The suture tension was significantly lower with the small bites technique and Duramesh™ when compared with large bites (small bites 0.12 N (IQR 0.07-0.19) vs. large bites 0.57 N (IQR 0.23-0.92), p  < 0.025). This significant difference was also found in favour of the small bites with PDS II 2-0 (p  < 0.038). No macroscopic tissue failure was seen during or after the experiments.

CONCLUSION

Closure of the abdominal wall with the small bites technique and Duramesh^™ was more efficient in dividing suture tension across the incision when compared to large bites. However, suture tension compared to a conventional suture material was not significantly different, contradicting an advantage of the new suture material in the prevention of burst abdomen and incisional hernia during the acute, postoperative phase.

Suture-Based Debris Behavior in the Draining Lymph Nodes of a Porcine Knee: A Study of Silicone, Polyethylene and Carbon

Purpose

To determine whether debris from a silicone core suture has an observable intra-articular or extra-articular impact or can be shown to migrate into the lymphatic system.

Methods

Using a porcine stifle joint model, 2 study groups were created: 1 group used silicone-suture particles created by rupturing hand-tied knots of a nonabsorbable suture with an outer sheath of ultrahigh molecular-weight polyethylene, an inner polyester sheath and a medical-grade silicone/sodium chloride-filled core. The second group used a mixture of 3 vitreous carbon particles sizes. Twelve Yorkshire pigs were randomly assigned to each group. Only 1 type of study particle was used in a single animal to avoid cross-contamination. Half of the study materials were placed by arthrotomy into the joint and, after capsular closure, the remaining half were placed on the joint capsule before skin closure. Six weeks postimplantation, the stifle joints and regional lymph nodes were examined macroscopically and microscopically. The extracapsular and intra-articular tissue and the lymph nodes were examined.

Results

Macroscopically, none of the 12 silicone-suture particle group limbs had abnormal macroscopic observations. Of the 12 limbs in the carbon particle group, 8 demonstrated discoloration in the extracapsular, intra-articular and lymph node tissues; 6 limbs demonstrated joint discoloration (extracapsular and intra-articular). The silicone-suture particle group showed lymph node inflammation in 25% of the iliac lymph nodes and 42% of the inguinal lymph nodes but none in the popliteal lymph nodes. In the carbon particle group, 100% of the iliac lymph nodes, 75% of the inguinal lymph nodes and 8% of the popliteal nodes showed inflammation. No silicone-suture debris migration was observed microscopically. Visible carbon particle migration was present in 100% of the iliac lymph nodes and in 50% of the inguinal lymph nodes but in none (0) of the popliteal lymph nodes. The carbon particle group also showed inflammation in these areas.

Conclusions

Carbon particles in the porcine knee migrated into the lymph nodes (iliac 100%; inguinal 50%, popliteal 0); gross discoloration was observed in 8 of 12 specimens. Silicone-suture particles could not be found in the lymph nodes, and no macroscopic joint damage was observed.

Clinical Relevance

The clinical use of a suture containing a silicone/salt central core is common, and the porcine lymphatic model suggests that this type of suture material does not result in clinically significant silicone particulates.

Theoretic and Evidence-Based Laparotomy Closure with Sutures and Meshes

The ultimate tensile strength of newly apposed tissue is the sum of the strength of the physical construct holding the tissues and the strength of biologic healing. For successful incisional hernia repair, the total strength of the repair must remain greater than the forces applied. While much work has been done to understand the science of wound healing-the ability of an open defect to contract and close-far less has been done to understand the healing of 2 newly approximated previously nonwounded surfaces held together with sutures or other implants. In this article, the elements of ultimate tensile strength on laparotomy closure as well as their progression over time will be related to clinical studies of abdominal wall closure.

Influence of Elevated Intra-abdominal Pressure on Suture Tension Dynamics in a Porcine Model

BACKGROUND

Inadequate suture tension is a risk factor for the failure of laparotomy closure. Suture tension dynamics in the abdominal wall are still obscure due to the lack of measuring devices. To answer the questions if intra-abdominal hypertension (IAH) influences suture tension in midline laparotomies and if IAH leads to a permanent loss of suture tension, microsensors were applied in a porcine model of IAH.

MATERIAL AND METHODS

Microsensors measuring suture tension "on the thread" with a frequency of 1/s were developed and implanted in the suture lines of midline laparotomies in four pigs. During a 23-h experiment under general anesthesia, two intervals of IAH (30 mm Hg) were applied, interrupted by a 3-h interval without elevated intra-abdominal pressure.

RESULTS

All sensors showed an immediate and reproducible response to changes of intra-abdominal pressure. The two 9-h periods of IAH resulted in a significant elevation of suture tension (P = 0.003 and P = 0.0009, respectively). Reducing the IAH lead to a significant loss of suture tension (P = 0.0005 and P = 0.0001, respectively). After the second interval with IAH, a complete loss of mean suture tension was observed. A statistically significant "recovery" of suture tension in the interval between the two phases with IAH was not observed.

CONCLUSIONS

Intervals with elevated intra-abdominal pressure have a direct influence on suture tension in midline laparotomy wounds. Intervals with IAH lead to a significant loss of suture tension in the suture line and to a complete loss of mean suture tension at the end of this experiment. A subsequent gaping of the fascia might contribute to either acute or chronic failure of laparotomy closure.

Comparison of cosmetic appearances after facial lacerations repaired by junior residents and experts

PURPOSE

The technical factors which improve cosmetic outcomes and which need to be emphasized in education of junior residents have yet to be described. We compared cases in which suturing was performed by either junior emergency medicine residents or experts, in order to determine the focus of future education and training.

METHODS

Wound registry data was reviewed and retrospectively analyzed from September 2015 to February 2016. Only patients who visited the emergency room with facial lacerations were enrolled, and their wound registry data sheets were reviewed. Practitioners were divided into junior resident and expert groups. We assessed the progress using the Stony Brook Scar Evaluation Scale (SBSES) 5-10 days following suturing.

RESULTS

Sixty-six patients were enrolled; 43 (65.2%) were men. The median (interquartile range) cosmetic scores (SBSES scale) for suturing performed by junior residents or experts were 3 (2-4) and 5 (4-5), respectively (p = 0.001). The percentage of maximum scores for each SBSES category was significantly lower in the junior resident group than in the expert group for width (68% vs. 86%), hatch marks (68% vs. 93%), and overall appearance (41% vs. 80%) (all p < 0.001).

CONCLUSIONS

There were significant differences in scar widths and hatch marks, which were attributable to the skill level of the practitioner who performed the suturing of facial lacerations. Junior residents should be educated about maintenance of proper tension, atraumatic technique, and performing appropriate trimming or debridement.

Miniaturized Sensors Registering the Long-Term Course of Suture Tension In Vivo under Varying Intra-Abdominal Pressure

BACKGROUND

Failure of laparotomy closure develops after up to 20% of abdominal operations. Suture tension has an influence on the quality of tissue regeneration. No sensors are available to register suture tension dynamics in vivo.

METHODS

In a series of animal experiments, the effect of suture tension on the ultrastructure of the healing incision was examined. Surgeons' ability to suture with target tension was tested. An implantable sensor and data logger were developed and tested experimentally in sutures closing midline laparotomies in pigs both under normal and elevated intra-abdominal pressure.

RESULTS

High suture tension has a negative influence on the regeneration of laparotomy incisions. Running sutures for laparotomy closure lose 45% of their initial tension over periods of 23 h. Intermittent elevation of intra-abdominal pressure to 30 mm Hg leads to a near total loss of suture tension after 23 h.

CONCLUSION

Surgeons are not able to control and reproduce suture tension. Suture tension dynamics can be measured in vivo by the sensor developed. Further research is needed to define a tissue-specific suture tension optimum to reduce the incidence of complications after laparotomy. Techniques for laparotomy closure need to be modified.

Surgical sutures: coincidence or experience?

BACKGROUND

Knotting sutures by hand is still important in daily surgical routine, especially laparotomy closure. The expectation is that hand suturing relies on the experience and subjective estimation of the surgeon. The aim of this study was to investigate whether hand suturing tension is reproducible and if surgical experience influences reproducibility.

METHODS

At the annual Congress of the German Association of Surgery, 118 surgeons performed repetitive sutures on a standardized and certified measuring device simulating the final knot of a fascial closure. Each surgeon was asked to perform five identical single knots in a row using the suture tension that each considered ideal. Tension during knotting was measured in Newtons. The surgeons were divided into five subgroups based on surgical experience: group 1, <1 year; group 2, 2-5 years; group 3, 6-10 years; group 4, 11-20 years; and group 5, >30 years.

RESULTS

The tension measured at the end of knotting ranged from 0.19 to 10 N. The mean suture tension at endpoint was 3.88 N for group 1 and slightly higher in the other groups, but not significantly different. The overall mean suture tension was 5.43 N and did not correlate with surgical experience. Suture tension was not reproducible.

CONCLUSION

Sequential suture tension varied, even among experienced surgeons. The ideal tissue-dependent suture tension has not been defined. Measured values appear to be intuitive, relying on individual feeling rather than the level of experience.

Development of incisional herniation after midline laparotomy

BACKGROUND

Incisional herniation is a common complication after abdominal surgery associated with considerable morbidity. The aim of this study was to determine whether incisional hernia is an early complication, in order to understand better the aetiology of incisional hernia formation.

METHODS

This study involved the secondary analysis of a subset of patients included in a large RCT comparing small and large tissue bites (5 mm every 5 mm, or 1 cm every 1 cm) in patients scheduled to undergo elective abdominal surgery by midline laparotomy. The distance between the rectus abdominis muscles (RAM distance) was measured by standardized ultrasound imaging 1 month and 1 year after surgery. The relationship between the 1-year incidence of incisional hernia and the RAM distance at 1 month was investigated.

RESULTS

Some 219 patients were investigated, 113 in the small-bites and 106 in the large-bites group. At 1 month after surgery the RAM distance was smaller for small bites than for large bites (mean(s.d.) 1·90(1·18) versus 2·39(1·34) cm respectively; P = 0·005). At 1 year, patients with incisional hernia had a longer RAM distance at 1 month than those with no incisional hernia (mean(s.d.) 2·43(1·48) versus 2·03(1·19) cm respectively; relative risk 1·14, 95 per cent c.i. 1·03 to 1·26, P = 0·015).

CONCLUSION

A RAM distance greater than 2 cm at 1 month after midline laparotomy is associated with incisional hernia. Closure with small bites results in a smaller distance between the muscles.

[Do we need to relearn abdominal wall closure? : Small stitches]

The 1‑year incisional hernia rate of 9-30 % has been tolerated for decades. Even in the 1970s and 1980s there was evidence that supported reducing suture tension. Recently, the traditional 4:1 relationship between suture and wound length, which has been passed on for years, has been questioned. After first experimental and clinical data suggested an advantage by reducing the width and interval of stitches by 50 %, the prospective randomized STITCH study has now provided evidence by significantly lowering the 1‑year hernia rate from 21 % to 13 %. For surgeons this means less of a revolution and more of an innovative evolution of a long-established technique. Before introduction of the technique quality assurance must be carried out with documentation of performance indicators (e.g. number of stitches, length of thread incorporated and wound length).

Characterisation of a novel light activated adhesive scaffold: Potential for device attachment

The most common methods for attaching a device to the internal tissues of the human body are via sutures, clips or staples. These attachment techniques require penetration and manipulation of the tissue. Tears and leaks can often be a complication post-attachment, and scarring usually occurs around the attachment sites. To resolve these issues, it is proposed to develop a soft tissue scaffold impregnated with Rose Bengal/Chitosan solution (RBC-scaffold, 0.01% w/v Rose Bengal, 1.7% w/v Medium Molecular Weight Chitosan). This scaffold will initially attach to the tissue via a light activation method. The light activates the dye in the scaffold which causes cross-links to form between the scaffold and tissue, thus adhering them together. This is done without mechanically manipulating the surrounding tissue, thus avoiding the issues associated with current techniques. Eventually, the scaffold will be resorbed and tissue will integrate for long-term attachment. A variety of tests were performed to characterise the RBC-scaffold. Porosity, interconnectivity, and mechanical strength were measured. Light activation was performed with a broad spectrum (380-780nm) 10W LED lamp exposed to various time lengths (2-15min, Fluence range 0.4-3J/cm(2) ). Adhesive strength of the light-activated bond was measured with lap-shear tests performed on porcine stomach tissue. Cell culture viability was also assessed to confirm tissue integration potential. These properties were compared to Variotis™, an aliphatic polyester soft tissue scaffold which has proven to be viable for soft tissue regeneration. The RBC-scaffolds were found to have high porosity (86.46±2.95%) and connectivity, showing rapid fluid movement. The elastic modulus of the RBC-scaffolds (3.55±1.28MPa) was found to be significantly higher than the controls (0.15±0.058MPa, p<0.01) and approached reported values for human gastrointestinal tissue (2.3MPa). The maximum adhesion strength achieved of the RBC-scaffolds was 8.61±2.81kPa after 15min of light activation, this is comparable to the adhesion strength of fibrin glue on scaffolds. Cell attachment was seen to be similar to the controls, but cells appeared to have better cell survivability. In conclusion, the RBC-scaffolds show promise for use as a novel light activated attachment device with potential applications in attaching an anti-reflux valve in the lower oesophagus and also in wound healing applications for stomach ulcers.

An implantable sensor device measuring suture tension dynamics: results of developmental and experimental work

PURPOSE

Knowledge about suture tension dynamics after laparotomy closure is limited due to the lack of adequate measurement tools. As a consequence, a miniaturized implantable sensor and data logger were developed and applied experimentally in a porcine model to measure suture tension dynamics after laparotomy closure.

MATERIAL AND METHODS

We developed an implantable device (6 × 3 × 1 mm) fitted with silicon strain gauges and an implantable data logger allowing long-term registration. In nine domestic pigs, sensors and loggers were implanted along the suture closing a median laparotomy registering suture tension over a period of 23 h.

RESULTS

Fascial closure was achieved by a mean suture tension of 1.07 N. After 30 minutes, suture tension was reduced to 0.81N (-24.3 %, p = 0.0003). After 12 h, tension showed a further decrease to 0.69 N (-35.5 %, n.s.), after 23 h mean suture tension reached 0.56 N, (-47.7 %, p = 0.014).

CONCLUSIONS

The aim to develop an implantable miniaturized sensor device registering long-term suture tension dynamics was achieved. The use in the animal experiment was feasible and safe. We observed a loss of almost 50 % of suture tension 23 h after fascial closure. This could mean that up to 50 % of initial suture tension may be an unnecessary surplus not contributing to tissue stability but to the risk of suture failure.

Small bites versus large bites for closure of abdominal midline incisions (STITCH): a double-blind, multicentre, randomised controlled trial

BACKGROUND

Incisional hernia is a frequent complication of midline laparotomy and is associated with high morbidity, decreased quality of life, and high costs. We aimed to compare the large bites suture technique with the small bites technique for fascial closure of midline laparotomy incisions.

METHODS

We did this prospective, multicentre, double-blind, randomised controlled trial at surgical and gynaecological departments in ten hospitals in the Netherlands. Patients aged 18 years or older who were scheduled to undergo elective abdominal surgery with midline laparotomy were randomly assigned (1:1), via a computer-generated randomisation sequence, to receive small tissue bites of 5 mm every 5 mm or large bites of 1 cm every 1 cm. Randomisation was stratified by centre and between surgeons and residents with a minimisation procedure to ensure balanced allocation. Patients and study investigators were masked to group allocation. The primary outcome was the occurrence of incisional hernia; we postulated a reduced incidence in the small bites group. We analysed patients by intention to treat. This trial is registered at Clinicaltrials.gov, number NCT01132209 and with the Nederlands Trial Register, number NTR2052.

FINDINGS

Between Oct 20, 2009, and March 12, 2012, we randomly assigned 560 patients to the large bites group (n=284) or the small bites group (n=276). Follow-up ended on Aug 30, 2013; 545 (97%) patients completed follow-up and were included in the primary outcome analysis. Patients in the small bites group had fascial closures sutured with more stitches than those in the large bites group (mean number of stitches 45 [SD 12] vs 25 [10]; p<0·0001), a higher ratio of suture length to wound length (5·0 [1·5] vs 4·3 [1·4]; p<0·0001) and a longer closure time (14 [6] vs 10 [4] min; p<0·0001). At 1 year follow-up, 57 (21%) of 277 patients in the large bites group and 35 (13%) of 268 patients in the small bites group had incisional hernia (p=0·0220, covariate adjusted odds ratio 0·52, 95% CI 0·31-0·87; p=0·0131). Rates of adverse events did not differ significantly between groups.

INTERPRETATION

Our findings show that the small bites suture technique is more effective than the traditional large bites technique for prevention of incisional hernia in midline incisions and is not associated with a higher rate of adverse events. The small bites technique should become the standard closure technique for midline incisions.

FUNDING

Erasmus University Medical Center and Ethicon.

Polyvinylidene Fluoride as a Suture Material: Evaluation of Comet Tail-Like Infiltrate and Foreign Body Granuloma

Background: Biocompatibility and tissue integration of a surgical suture are decisive factors for wound healing and therefore for the success of sutures. The optimal suture material is still under discussion. Polyvinylidene fluoride (PVDF) is described to have superior properties of biocompatibility and is therefore frequently used as a mesh component. Only little information is available about its use as a suture material. The aim of this study was to evaluate the biocompatibility of PVDF as a suture material in comparison to 5 different established sutures in a rat model. Methods: In 30 male rats, a monofilamental PVDF suture (Resopren®) and 5 established control suture materials [polyester (Miralene®), polytetrafluoroethylene (Gore®), poliglecaprone (Monocryl®), polydioxanone (Monoplus®), polyglactin 910 (Vicryl®), USP size 3-0] were placed in the subcutaneous layer of the abdominal wall without knot or tension. After 3, 7 or 21 days, the abdominal walls were explanted for histopathological and immunohistochemical investigation with special regard to the size and quality of foreign body granuloma and the length of the comet tail-like infiltrate (CTI). Results: The PVDF sutures showed the smallest size of foreign body granuloma (60 ± 14 µm) and the smallest CTI length (343 ± 60 µm) of all polymers after 21 days. Only PVDF (Resopren) and polydioxanone (Monoplus) showed a significant collagen I/III ratio increase between days 3 and 21 (p = 0.009 and p = 0.016). The quality of foreign body reaction regarding inflammation, proliferation and fibrotic remodeling was similar between all suture materials. Conclusions: Our data indicate that monofilamental PVDF sutures show a favorable foreign body reaction with small granuloma sizes and CTI length in comparison to established sutures. Its use as a suture material in general surgery could therefore be extended in the future. To reinforce these findings, further clinical studies need to be conducted.

Force sensing in surgical sutures

The tension in a suture is an important factor in the process of wound healing. If there is too much tension in the suture, the blood flow is restricted and necrosis can occur. If the tension is too low, the incision opens up and cannot heal properly. The purpose of this paper is to describe the design and evaluation of the Stitch Force (SF) sensor and the Hook-In Force (HIF) sensor. These sensors were developed to measure the force on a tensioned suture inside a closed incision and to measure the pulling force used to close the incision. The accuracy of both sensors is high enough to determine the relation between the force in the thread of a stitch and the pulling force applied on the suture by the physician. In a pilot study, a continuous suture of 7 stitches was applied on the fascia of the abdominal wall of multiple pigs to study this relationship. The results show that the max force in the thread of the second stitch drops from 3 (SD 1.2) to 1 (SD 0.3) newton after the 4(th) stitch was placed. During placement of the 5(th), 6(th) and 7(th) stitch, the force in the 2(nd) stitch was not influenced anymore. This study indicates that in a continuous suture the force in the thread remains constant up to more than 3 stiches away from the pulled loose end of the suture. When a force feedback tool is developed specially for suturing in surgery on patients, the proposed sensors can be used to determine safety threshold for different types of tissue and sutures.

Comparison of intestinal microcirculation and wound healing in a rat model

PURPOSE

If a colonic or small bowel lesion is not accessible for endoscopic mucosal resection, enterotomy is a possible although rarely performed surgical technique. It has never been compared to circular anastomosis regarding leakage rate, bowel wall perfusion, and wound healing. Thus, the aim of this basic experimental scientific study was to investigate perianastomotic microcirculation and wound healing.

METHODS

Forty rats were divided into four groups (1 jejunal anastomosis, 2 jejunal enterotomy, 3 colonic anastomosis, and 4 colonic enterotomy). Following anastomosis and enterotomy, the intestinal perfusion was measured using laser fluorescence angiography (IC-View). On postoperative day 7, the surface of the mucosal villi, expression of matrix metalloproteinases (MMP) 2, 8, 9, and 13, and the number of proliferating cells (Ki67) as well as the collagen types I/III ratio were analyzed.

RESULTS

The perianastomotic microperfusion was significantly reduced in all groups compared to the reference region. The perianastomotic perfusion index was significantly reduced in group 1 compared with group 2, whereas the perfusion index in group 3 was slightly but not significantly reduced in comparison to group 4. Ki67 was elevated in both circular anastomosis groups. Surface of the mucosal villi, MMP expression, and collagen type I/III ratio revealed no significant differences.

CONCLUSIONS

Our study affirms the theoretical consideration of a better microperfusion of the bowel wall following an antimesenterial enterotomy and demonstrates that enterotomy is not inferior compared to circular anastomosis. Even though enterotomy is a rarely used surgical technique, it should be regarded as a possible alternative in particular situations.