Physical, biological and handling characteristics of surgical suture material: a comparison of four different multifilament absorbable sutures

OBJECTIVE

Four different braided absorbable surgical materials (Dexon, Dexon II Bicolor, Vicryl and Polysorb) 2/0 USP, which basically share the same indications, were studied in vitro and in vivo with regard to their physical properties as well as tissue compatibility and surgical handling. Analyzing the results the authors tried to determine the most useful suture in surgical practice.

METHOD

Physical tests to determine tensile strength, knot-breaking strength and knot security were carried out. Additionally an in vivo model (Wistar rat) was used to compare histocompatibility and loss of function due to hydrolytic resorption. Furthermore, a handling test was carried out by trained surgeons.

RESULTS

Polysorb had the highest linear tensile strength but also the fastest loss of function following tissue implantation, whereas Vicryl showed the slowest loss of function. Similar results were obtained with regard to the knot-breaking strength. After pulsatile stressing Dexon II Bicolor and Dexon showed the highest irreversible elongation followed by Vicryl and Polysorb. Polysorb had the best knotting characteristics, scoring highest also in the handling study.

CONCLUSIONS

The authors conclude that with Polysorb all features and properties of braided suture material have reached a high level of quality. This suture combines the positive characteristics of monofilament with those of multifilament materials, thus coming closest to being the 'optimal suture'.

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

OBJECTIVE

To determine failure strength, stiffness, and failure mode of 4 suture materials in equine linea alba.

STUDY DESIGN

Randomized complete block design.

SAMPLE POPULATION

Linea albas collected from 12 adult horses (mean weight, 475 kg; mean age, 10 years).

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

CLINICAL RELEVANCE

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.

Impact of chromic catgut versus polyglactin 910 versus fast-absorbing polyglactin 910 sutures for perineal repair: a randomized, controlled trial

OBJECTIVE

The goal of our study was to compare the impact of 3 suture materials on perineal pain and on resumption of sexual intercourse.

STUDY DESIGN

This randomized, controlled trial compared 3 types of suture materials (chromic catgut, polyglactin 910, fast-absorbing polyglactin 910) for second-degree perineal laceration or uncomplicated episiotomy. Patients were enrolled in early labor and assigned randomly to 1 of the 3 suture materials. Pain was evaluated at 48 hours, 6 weeks, and 3 months. The study subjects were questioned about residual perineal pain, resumption of sexual activity, and pain-free sexual intercourse. Logistic regression analyses were undertaken.

RESULTS

Of the 192 patients who were assigned randomly to groups, 66 patients had their perineal laceration repaired with chromic catgut; 60 patients had repair with polyglactin 910, and 66 patients had repair with fast-absorbing polyglactin 910. At 48 hours, there was no significant difference according to the pain measurement scores, but the median consumption of analgesics was significantly lower with fast-absorbing polyglactin 910 than with standard polyglactin 910. There was no difference in the resumption of sexual intercourse at 6 weeks after the delivery between chromic catgut (42%) compared with standard polyglactin 910 group (56%; P = .23). However, it was more frequent for women in the fast-absorbing polyglactin 910 group (66%; P = .02). After adjustment for confounding variables, perineal repair with fast-absorbing polyglactin 910 was associated with a higher rate of sexual intercourse (odds ratio, 2.55; 95% CI, 1.07-6.10) and a higher rate of pain-free sexual intercourse (odds ratio, 2.51; 95% CI, 1.03-6.10) at 6 weeks after delivery.

CONCLUSION

Fast-absorbing polyglactin 910 for perineal repair is associated with earlier resumption of sexual intercourse when compared with chromic catgut.

In Vitro Bursting Pressures of Jejunal Enterotomy Closures in Llamas

OBJECTIVE

To evaluate closure strength (in vitro bursting pressure) of jejunal enterotomies in llamas.

STUDY DESIGN

In vitro experimental study.

SAMPLE POPULATION

Jejunal specimens (n=72) from 6 llamas.

METHODS

Differences in bursting pressures and luminal diameters were compared between 2 layer enterotomy closures with an initial full thickness simple continuous pattern oversewn with either a continuous Lembert or Cushing suture pattern using 3 sizes (2-0, 3-0, 4-0) of polyglactin 910 and polydioxanone.

RESULTS

Bursting pressures were significantly higher for enterotomies closed with polydioxanone than polyglactin 910, independent of suture size, but there was no difference between Lembert and Cushing oversew patterns. Use of a Lembert pattern reduced intestinal diameter more than a Cushing pattern regardless of suture material or size.

CONCLUSIONS

Although polydioxanone resisted higher bursting pressures than polyglactin 910, both suture materials should be considered satisfactory for jejunal enterotomy closure in llamas based on typical intraluminal pressures expected in clinical patients. The optimal oversew pattern may be continuous Cushing to maximize the luminal diameter in small intestinal enterotomy closures.

CLINICAL RELEVANCE

In vitro bursting pressures may help to predict which enterotomy sites would leak post-operatively, although further studies are necessary to determine the outcome in clinical patients.

A comparative study of polydioxanone (PDS) and polyglactin 910 (Vicryl) in colonic anastomoses in rats

The use of polyglactin 910 (Vicryl) in colonic anastomoses is theoretically undesirable because its short dissolution time and multifilament structure may lead to local sepsis and anastomotic leakage. We have compared Vicryl with a newly introduced monofilament absorbable suture which has a longer dissolution time than Vicryl. In a study of 98 rat colonic anastomoses no difference was found in complication rates or cellular reaction to the suture material between Vicryl and polydioxanone (PDS). The use of monofilament suture with longer dissolution time does not necessarily imply added security for colonic anastomoses.

Operative Standardisierung bei randomisiert kontrollierten Studien in der Chirurgie

BACKGROUND

INSECT is an internationally registered, three-armed, multicentre, intraoperatively randomised model trial of the Study Centre of the German Surgical Society. The interventions being compared are running suture technique with slowly absorbable monofilament suture material (PDS vs MonoPlus) and interrupted technique with a braided, rapidly absorbable suture material (Vicryl). The primary endpoint is the rate of incisional hernias 1 year postoperatively.

MATERIAL AND METHODS

A total of 25 surgeons from 24 different institutions at all levels of care evaluated the theoretical and practical sessions of the surgical investigator meeting using 25 criteria, including course organisation, content, and speaker evaluation, and a categorical grading system from 1 (very good) to 6 (insufficient).

RESULTS

Distribution of the 625 grades was: very good (1) n=367, good (2) n=207, satisfactory (3) n=39, adequate (4) n=2, and "No statement" n=10. The average score for the investigator meeting was 1.5.

CONCLUSION

The participants felt they were successfully prepared theoretically and practically for trial interventions and conduct by attending the meeting. Clear explanation of the measures for treatment equivalence before and during trials is mandatory in randomised controlled surgical trials.

Knot integrity as a function of suture expiration

OBJECTIVE

To test the integrity of knots tied with expired suture and non-expired suture, using 5 different suture materials.

STUDY DESIGN

Knots were tied using expired and non-expired chromic catgut, polyglactin 910, polydioxanone, silk, or coated polyester. Expired sutures were a mean of 10.5 years past the date of expiration stamped on the packaging. Suture packaging was inspected for any flaws or humidity. There were 116 knots with expired suture and 109 non-expired knots. All knots were tied by hand. Suture was soaked in 0.9% sodium chloride for 60 seconds and subsequently transferred to a tensiometer where the tails of the knots were cut to 3 mm length. We compared the tensile strength of knots using a tensiometer to pull the knots until the suture broke or untied. A minimum of 30 knots were needed in order to detect a statistically significant main effect for expired and non-expired sutures with 80% power and a 5% chance of type I error.

RESULTS

A total of 225 knots were tied. Overall, we found no difference in mean tension between expired suture (77.5 ± 31.7 N) and non-expired suture at failure (81.9 ± 30.2 N). All the sutures broke at the knot and none untied. Expired chromic and polydioxanone were significantly weaker than the non-expired suture of the same material (p = 0.002 and p = 0.001, respectively). There was no statistically significant difference in tensile strength between expired absorbable or permanent suture materials. Based on a univariate analysis of variance ([SCAP]ANOVA)[R] there was no difference in the tension at failure between expired and non-expired sutures with suture packet as a covariate. No suture untied when knotted with expired suture.

CONCLUSIONS

Under laboratory conditions, expired chromic and polydioxanone sutures broke at lower tensile strength than non-expired sutures of the same material.

Mechanical performance of polyglycolic acid and polyglactin 910 synthetic absorbable sutures

The mechanical performance of polyglycolic acid and polyglactin 910 sutures has been assessed using standardized reproducible tests. The results of these studies demonstrated distinct differences in their performance that can be related, in part, to their structural configuration. The size of the 4-0 polyglactin suture was significantly larger than that of the 4-0 polyglycolic acid suture. Since the strength of any suture is proportional to its cross sectional area, the strength of unknotted and knotted polyglactin 910 sutures was signficantly greater than that of the polyglycolic acid sutures. The strength of both sutures was similarly diminished by the formation of the knot. When these sutures were added to tissue, the breaking strength was even further reduced. The rate of decline in breaking strength of the two absorbable sutures in healing skin wounds was comparable. These absorbable sutures displayed knot security with a two throw square knot, 1 = 1. The ability of these sutures to reach knot break with this knot configuration is characteristic of sutures in which the surface exhibits a high coefficient of friction. Their rough surface also caused them to drag through tissue, making difficult to adjust tension on a continuous running suture.

Medical devices; reclassification and codification of absorbable poly(glycolide/L-lactide) surgical suture--FDA. Final rule

The Food and Drug Administration (FDA) is announcing the reclassification and codification of the absorbable poly(glycolide/L-lactide) surgical suture (PGL suture). FDA issued an order in the form of a letter to the manufacturer reclassifying the PGL suture from class III into class II.

[Behavior of modern suture materials in infected urine]

The recently developed absorbable materials demonstrate a constant and reproducible high quality when compared with the resorbable suture materials. However, based on in vitro studies by different authors the use of these materials in infected urine is not recommended. We investigated in vivo in infected urines the stability of the suture materials composed of polyglycolic acid, and compared the results obtained in vitro and in vivo. In a controlled study the stability of the absorbable suture materials polyglycolic acid, polyglactin 910 and polydioxanon 4/0 USP were tested in infected urine in vivo and in vitro. In 21 patients with infected urine the suture materials were placed into the bladder for 7 days. In another experiment these materials were incubated up to 7 days in culture flasks with infected urine. After that the suture materials were examined by densitometry and electrone microscopy. When using the results obtained in vitro in clinical work caution is recommended. However, the in vivo tests show that the stability of the newly developed absorbable materials is not influenced dramatically by the infected urine.

Histologic reactions to polyglactin-910, polyethylene and nylon microsuture

Three froms of 10-0 microsuture-monofilament polyglactin-910, polyethylene and nylon-were tested for histologic reaction. Polyglactin had the least long-lived reaction.

Breaking strength and diameter of absorbable sutures after in vivo exposure in the rat

Although absorbable sutures are commonly used in clinical practice, the rate of decay of strength in various tissues has not been studied. The purpose of this study was to assess breaking strength (BS) and diameter of monofilament (chromic gut, polydiaxanone, Maxon, Monocryl) and multifilament (Vicryl, Dexon, Polysorb) absorbable sutures implanted in various sites and measured at specific time intervals. A 15 cm length of 4-0 suture from a single lot of each material was implanted in the pleural space, rectus abdominus muscle, subcutaneous tissue, intravascular space, peritoneal cavity, and stomach lumen in the rat. A precipitous decrease in BS was noted in all multifilament sutures after 7 days, and in chromic gut and Monocryl sutures after 1 day. Polydiaxanone and Maxon sutures maintained the highest BS over the 28-day period, 71 per cent and 59 per cent of their initial BS, respectively. Suture diameter remained essentially unchanged except for chromic gut and the multifilament sutures which exhibited increased diameter. This increase was attributed to inflammatory tissue infiltration.

[Experimental and clinical study of conjunctivo-scleral tolerance of PTFE (Goretex) sutures compared to polyglactine (Vicryl)]

The authors report a study of the modifications observed with sutures of PTFE (Goretex) and polyglactin (Vicryl) at the level of the sclera and the conjunctival. Inflammatory cells are fewer with PTFE both in the rabbit eyes (14 cases) from 3 to 110 days and in the human eye in a clinical study of 28 cases.