Sutures. I. Introduction Sutures are probably the largest group of devices implanted in humans. Although they seem to be of small concern to the medical.

SuturesSutures

I. IntroductionI. Introduction

Sutures are probably the largest group of devices implanted in humans. Although they seem to be of small concern to the medical community, few devices have been made of so many different materials. By definition, a suture is a thread that either approximates and maintains tissues until the natural healing process has provided a sufficient level of wound strength or compresses blood vessels in order to stop bleeding.

II. HistoryII. History

Since the beginning of surgical history (5000-3000 BC), sutures have been used as the means of repairing damaged tissues, cut vessels, and surgical incisions. As time has passed, a variety of suture materials have been used: flax, hair, linen strips, pig bristles, grasses, mandibles of pincher ants, cotton, silk, the gut of an animal, nylons, polyesters, and metals. The earliest use of gut can be traced back to the ancient Greek physician Galen. The eighteenth century brought the use of buckskin and silver wire, and the nineteenth brought the ability to chemically alter the properties of gut. By the twentieth century, cotton and treated natural materials have come to be the most widely used materials for suturing. After the invention of nylon and polyester propagated the popularity of cotton and treated natural materials, polyethylene, polypropylene, polyglycolic acid, polyglactin 910, and a large number of textile materials entered into the menu of choices for sutures.

III. RegulationIII. Regulation

The United States Pharmacopoeia (USP) is the official compendium for the suture industry. It sets standards and guidelines for suture manufacture. Suture sizes are given by a number representing diameter ranging in descending order from 10 to 1 and then 1-0 to 12-0, 10 being the largest and 12-0 being the smallest at a diameter smaller than a human hair.

IV. ClassificationIV. Classification

Sutures can be classified into one of two groups, absorbable and nonabsorbable. Absorbable sutures are, as the name implies, temporary due to their ability to be “absorbed” or decomposed by the natural reaction of the body to foreign substances. It is important to note that not all absorbable sutures have the same resistance level to absorption, but each can be formulated or treated in order to obtain a desired decomposition rate. Nonabsorbable sutures are, in like manner, sutures that are not dissolved or decomposed by the body’s natural action. Such sutures are generally not naturally occurring materials (with the exception of silk). Silk & nylon, while being classified as nonabsorbable, actually dissolve after a long period of time compared to that of the absorbable materials

V. ManufacturingV. Manufacturing

Sutures are manufactured with a wide variety of parameters. They can be monofilament or many filaments twisted together, spun together, or braided. They can also be dyed, un-dyed, coated, or not coated. With the goal of understanding the effects of so many variations of suture type, the properties and material of which they are composed are and have been studied in depth. The use of sutures is one of the most common practices in the medical field and thus has direct effect on a great majority of the world’s population.

VI. DesignVI. Design

Currently, sutures are designed to result in the most desirable effect for any given situation as determined by those administering the sutures. Taken into consideration in the manufacture and use of sutures are properties such as stress-strain relationship, tensile strength, rate of retention, flexibility, intrinsic viscosity, wettability, surface morphology, degradation, thermal properties, contact angle of knots, and elasticity. Properties such as stress-strain relationship and tensile strength have a direct effect on how much force at a given rate the closure will be able to withstand. For example, a cough would impose a fast rate of elongation whereas edema or hemorrhage would impose a slow rate of elongation. Knotting causes a severe decrease of strength in the suture material. Thus when there is a break in the suture, it occurs most frequently at the site of the knot. As you can see, there are several factors biomedical engineers must consider when designing sutures.

VII. ApplicationVII. Application

Patient safety, as in every other area of the medical field, is one of the major determining factors of suture manufacture and use. As mentioned before, the composition and properties of a suture are the crucial elements in the decision of what type to use. For example,an incision into the lung would need to be closed using a suture with a high elasticity level, slow degradation rate, and high tension strength level. If a suture is applied in a situation in which it is not suitable, the patient’s safety is endangered. In short, a surgery is never successful if the wound, insertion point, or incision is not sutured or closed in a proper manner as to promote healing in a timely and safe fashion.

Another factor to be taken into consideration is the effect of inserting the suture into the tissue. If the suture is of a rough morphology (e.g. braided), the tissue will swell more and is more susceptible to infection than if a smooth suture (e.g. monofilament) is used. A failure of a suture is simply its breaking or not meeting the requirements for which it was intended.

VIII. TestingVIII. Testing

As technology advances, testing techniques improve and become more specific for the application of sutures. The greatest percentage of testing is done on those suture materials already existing in practice. This is due to the virtual newness of the application of testing techniques to the suture product although, a fairly small, yet increasingly important number of tests are done on possible new suture materials.

The USP determines the procedures and parameters for standard suture tests. Sutures are tested immediately after removal from their sterile packages without drying or conditioning. Sutures are tested in a variety of areas including accurate measurements, knot pull breaking strength, needle attachment, viscoelastic properties, tissue reaction and cell response, allergenicity and more. In all strength tests, it is important to keep in mind that the breaking strength retention of absorbable and nonabsorbable sutures should be considered separately because the strength retention of the absorbable sutures will be quite different than that of the nonabsorbable suture.

IX. Technological IX. Technological AdvancesAdvances

The use and need for a suture is clearly not a problem that needs a solution, but a solution that needs improvement. Currently there are many efforts to improve almost every aspect of the suture and its use. Also, new techniques for testing make it possible to gain a clearer understanding of the properties of sutures. This is necessary so that the most efficient and best suited suture will be applied in every case where a suture is needed. If it were not for the technological advances that have occurred in society, modern suture production and use would not exist and sutures would not be dependable.

ABSORBABLE SUTURESABSORBABLE SUTURES

NaturalNatural Natural suture are catgut of biological origin and are

protein in nature, their absorption and digestion is by proteolytic enzymes present in tissue fluid. The source is submueosa of sheep or serosa of intestine. Their fibres are then chrome tanned to delay absorption and twisted under tension and polished to achieve monofilament profile. Chrome tanning also reduces inflam matory response to tissue.

Serilization is achieved by Gamma radiation or ethylene oxide. Packing is done in fluid which retains its ideal handling characteristics, the fluid is 89% Isopropanol, 10% water and 1% Triethanolamine.

ABSORBABLABSORBABLE SUTURESE SUTURES

Uses: - Rapidly healing tissue - Hysterectomy- Caesarian Section- General Surgery- Ophthalmology

ABSORBABLE SUTURESABSORBABLE SUTURES NaturalNatural

Collagen is also of biological origin from ox Achilles tendom; rolled monofilament, undyed and uncoted.

Fascia Lata

ABSORBABLE SUTURESABSORBABLE SUTURES

SyntheticSynthetic

Polyglycolic acid (PGA) is available in two forms, the braided form is “Dexon” while the monofilament is “Maxon”. It is mane made homopolymer of glycolide. In monofilament form the flexibility in insufficient, therefore, braided form is used for general surgical use. Recently special coating of monofilament with polycaprolacton and glycolide has provided sufficient flexibility.

ABSORBABLE ABSORBABLE SUTURESSUTURES

Uses: OrthopaedicsSurgical OncologyDebilitated PatientsGen/Gyn (Fascia)Plastics

ABSORBABLE SUTURESABSORBABLE SUTURES SyntheticSynthetic

Polygalactin 910 “Vicryl”. A man-made copolymer of glycolide and lactate, is available in braided form. To reduce the tissue drag, the braided filaments are coated with calcium stearate, glycolide and lactate. Absorption is uniform and predictable, commencing at 40 days and complete between 60 and 90 days after implantation. Strength is greater than P.G.A. especially after 14 days. The inflammatory response is mild to moderate. Sterilization is by ethylene oxide.

ABSORBABLE ABSORBABLE SUTURESSUTURES

Uses: - Rapidly healing tissue- Episiotomy Repair- Skin Closure (except face)- Scalp- Under casts- Intra-oral mucosa

ABSORBABLE SUTURESABSORBABLE SUTURES SyntheticSynthetic Polydioxanone “PDS”: PDS is man-made

new copolymer, a polyester of paradioxanone, which is melt and a monofilament profile is achieved. It is the only suture which retains unique flexibility in mono filament form. Its strength is greater than that of all commonly used monofilament sutures other than steel.

Its monofilament profile makes it particularly useful in potentially infected tissues like colon, biliary system, stomach etc. Sterilization is by ethylene oxide.

ABSORBABLE ABSORBABLE SUTURESSUTURES

Uses: - long term healing applications (diabetics / oncology)- Plastics- Orthopaedics

ABSORBABLE SUTURESABSORBABLE SUTURES SyntheticSynthetic Polyglyconate – “Monocryl”:Polyglyconate – “Monocryl”: it is a it is a

man-made copolymer of glycolide and man-made copolymer of glycolide and caprolactone, in ratio of 72:25; it has clear, caprolactone, in ratio of 72:25; it has clear, undyed monofilament.undyed monofilament.

Uses: - Skin / Ob-Gyn / General / UrologyUses: - Skin / Ob-Gyn / General / Urology Polyglyconate – “Maxon”:Polyglyconate – “Maxon”: it ia man- it ia man-

made copolymer of 1,4-dioxane 2,5-dione made copolymer of 1,4-dioxane 2,5-dione and trimethylene carbonate; and trimethylene carbonate; monofilament, dyed or undyed.monofilament, dyed or undyed.

NONABSORBABLE NONABSORBABLE SUTURESSUTURES

NaturalNatural Silk: It is derived from thread spun by larva of silk

worm by degumming of surface albumin layer. The braided multifilament, dyed or undyed, coated or uncoated silk is known for excellent handling properties and knot security. Marked inflammatory reac tion, tissue drag and braiding are its main disabilities as braiding induces capillary attraction and hence harbor the infective agent in interstices. Tissue drag is over come by waxing or silicon coating reducing knot security, a third throw is always necessary. Fragmentation occurs and all tensile strength is lost by 9 months Sterilization is by Gamma radiation, however boiling and autoclaving may also be used.

NONABSORBABLE NONABSORBABLE SUTURESSUTURES

NaturalNatural

NONABSORBABLE NONABSORBABLE SUTURESSUTURES

NaturalNatural Cotton. It is cellulose in nature and occurs as

multifilament. Most of the proper ties are similar to those of silk except that strength of cotton increases when wet, where as silk loses 20% of strength when wet. Cotton is cheaper than all other sutures. It is available as dyed or undyed and uncoated.

Linen, It derived from falx plant; twisted multifilament, dyed or undyed and uncoated.

NONABSORBABLE NONABSORBABLE SUTURESSUTURES

NaturalNatural

NONABSORBABLE NONABSORBABLE SUTURESSUTURES

SyntheticSynthetic Polyamide: "Nylon". It can be

monofilament or multifilament dyed or undyed, generic name Nylon 6 or Nylon 66; trade name Ethilon (Uses: - ophthalmology - Skin Closure) or Dermalon (monofilament) and Nurolon (braided) or Surgilon (braided nylon).

Sterilization is by Gamma radiation but can tolerate autoclaving up to three times.

NONABSORBABLE NONABSORBABLE SUTURESSUTURES

SyntheticSynthetic

NONABSORBABLE NONABSORBABLE SUTURESSUTURES

SyntheticSynthetic Polyester; monofilament or multifilament,

dyed or undyed, coated or uncoated; trade name Ethibond (polybutylate coating) or Tri. Cron (silicon coating), and Mersilene orDacron (uncoated).' Polyesters are known for having high and permanent tensile strength, inducing only modest tissue reac tion and having good knot security. They are widely used in cardiovascular surgery.

NONABSORBABLE NONABSORBABLE SUTURESSUTURES

SyntheticSynthetic

NONABSORBABLE NONABSORBABLE SUTURESSUTURES

SyntheticSynthetic Polybutylester: monofilament, dyed or un-dyed,

polybutylene terphthalate and polytetramethylent ether glycol; trade name Novafil. Its "Mesh" forms are used for pair of vascular defects and Hernias.

Polyethylene: It is available in monofilament form as a strong suture, induces minima] tissue reaction, excellent knotting and handling due to its soft surface. Mesh form is also available. Progressive loss of strength occurs by fragmentation. Steriliza tion is done by Ethylene oxide or Gamma radiation. It melts at 132 С so autocaving can not be done.

NONABSORBABLE NONABSORBABLE SUTURESSUTURES

SyntheticSynthetic Polypropylene: monofilament dyed or

undyed; trade name is Prolene. It has a permanent high tensile strength, the most inert suture, better handling properties of knot security than Nylon. It has no memory to untie. Fragmentation does not occur within tissues. Its mesh forms are used in the repair of prolapse rectum. When used to suture blood vessels the blood loss is much less. Available in vivid blue colour which facilitates visualization during sur gery. Sterilization is by Ethylene oxide.

NONABSORBABLE NONABSORBABLE SUTURESSUTURES

SyntheticSynthetic

NONABSORBABLE NONABSORBABLE SUTURESSUTURES

SyntheticSynthetic PVDF. (Polyvinylidene fluoride)

monofilament, dyed or undyed. Its trade name is Trofilene.

Uses: Peripheral VascularCoronary Artery Bypass(Skin stage two)

NON ABSORBABLE NON ABSORBABLE METAL SUTURES.METAL SUTURES.

Stainless steel. Maintain tensile strength indefinitely- Monofilament or muftifilament.

i. Vitadium ii. Tantalum iii. Silver D. SURGICAL STAPLES AND CLIPS i. Absorbable. The concept of

Viscerosynthesis. ii. Non-Absorbable

SURGICAL SURGICAL NEEDLESNEEDLES

Requirements to Requirements to surgical needles: surgical needles: Minimal tissue traumaMinimal tissue traumaHigh sharpness (acuity)High sharpness (acuity)Corrosion resistanceCorrosion resistanceHigh strengthHigh strengthStable shapeStable shapeAbrasion resistanceAbrasion resistanceSmooth profileSmooth profile

Surgical needles are divided in two groups:

Traumatic needles Atraumatic needles

Traumatic needles - are needles with holes or eyes which are supplied to the hospital separate from their suture thread. In traumatic needles with eyes, the thread comes out of the needle's hole on both sides. When passing through the tissues, this type of suture rips the tissue to a certain extent, thus the name traumatic.

Atraumatic needles with sutures - comprise an eyeless needle attached to a specific length of suture thread. Important thing is that the suture end of a swaged needle is smaller than the needle body.

Atraumatic needle with attached suture thread

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