surgical suture surgical suture a surgical suture, also known as a stitch or stitches, is a medical device used to hold body tissues together and approximate wound edges after an injury or surgery. application generally involves using a needle with an attached length of thread. there are numerous types of suture which differ by needle shape and size as well as thread material and characteristics. selection of surgical suture should be determined by the characteristics and location of the wound or the specific body tissues being approximated. surgical suturesurgical suture and polypropylene thread on needle holder. packaging shown above. in selecting the needle, thread, and suturing technique to use for a specific patient, a medical care provider must consider the tensile strength of the specific suture thread needed to efficiently hold the tissues together depending on the mechanical and shear forces acting on the wound as well as the thickness of the tissue being approximated. one must also consider the elasticity of the thread and ability to adapt to different tissues, as well as the memory of the thread material which lends to ease of use for the operator. different suture characteristics lend way to differing degrees of tissue reaction and the operator must select a suture that minimizes the tissue reaction while still keeping with appropriate tensile strength. needles a surgeon suturing a wound in a person's thumb historically, surgeons used reusable needles with holes (called "eyes"), which are supplied separate from their suture thread. such suture must be threaded on site, as is done in embroidery sewing. the advantage of this is that any thread and needle combination is possible to suit the job at hand. swaged, or atraumatic, needles with sutures consist of a pre-packed eyeless needle attached to a specific length of suture thread. the suture manufacturer swages the suture thread to the eyeless atraumatic needle at the factory. the chief advantage of this is that the doctor or the nurse does not have to spend time threading the suture on the needle, which may be difficult for very fine needles and sutures. also, the suture end of a swaged needle is narrower than the needle body, eliminating drag from the thread attachment site. in eyed needles, the thread protrudes from the needle body on both sides, and at best causes drag. when passing through friable tissues, the eye needle and suture combination may thus traumatise tissues more than a swaged needle, hence the designation of the latter as "atraumatic". there are several shapes of surgical needles. these include: straight 1/4 circle 3/8 circle 1/2 circle. subtypes of this needle shape include, from larger to smaller size, ct, ct-1, ct-2 and ct-3. 5/8 circle compound curve half curved (also known as ski) half curved at both ends of a straight segment (also known as canoe) the ski and canoe needle design allows curved needles to be straight enough to be used in laparoscopic surgery, where instruments are inserted into the abdominal cavity through narrow cannulas. needles may also be classified by their point geometry; examples include: taper (needle body is round and tapers smoothly to a point) cutting (needle body is triangular and has a sharpened cutting edge on the inside curve) reverse cutting (cutting edge on the outside) trocar point or tapercut (needle body is round and tapered, but ends in a small triangular cutting point) blunt points for sewing friable tissues side cutting or spatula points (flat on top and bottom with a cutting edge along the front to one side) for eye surgery finally, atraumatic needles may be permanently swaged to the suture or may be designed to come off the suture with a sharp straight tug. these "pop-offs" are commonly used for interrupted sutures, where each suture is only passed once and then tied. sutures can withstand different amounts of force based on their size; this is quantified by the u.s.p. needles pull specifications. thread materials micrograph of a h&e stained tissue section showing a non-absorbable multi-filament surgical suture with a surrounding foreign-body giant cell reaction further information: suture materials comparison chart suture material is often broken down into absorbable thread versus non-absorbable thread, which is further delineated into synthetic fibers versus natural fibers. another important distinction among suture material is whether it is monofilament or polyfilament (braided) monofilament versus polyfilament: monofilament fibers have less tensile strength, but create less tissue trauma and are more appropriate with delicate tissues where tissue trauma can be more significant such as small blood vessels. polyfilament (braided) sutures are composed of multiple fibers and are generally greater in diameter with greater tensile strength, however, they tend to have greater tissue reaction and theoretically have more propensity to harbor bacteria. other properties to consider: tensile strength: the ability of the suture to hold tissues in place without breaking. elasticity: the ability of the suture material to adapt to changing tissues such as in cases of edema. tissue reactivity: inflammatory response of the surrounding tissue that can cause materials to break down quicker and lose tensile strength. non absorbable synthetic suture have the lowest of tissue reactivity, while the absorbable natural fibers have the highest rates of tissue reactivity. knot security: the ability of the suture to maintain a knot that holds the thread in place. absorbable absorbable sutures are either degraded via proteolysis or hydrolysis and should not be utilized on body tissue that would require greater than two months of tensile strength. it is generally used internally during surgery or to avoid further procedures for individuals with low likelihood of returning for suture removal. to-date the available data indicates that the objective short-term wound outcomes are equivalent for absorbable and non-absorbable sutures, and there is equipose amongst surgeons. natural absorbable: includes plain catgut, chromic catgut and fast catgut which are all produced from the collagen extracted from bovine intestines. they are all polyfilaments which have different degradations times ranging from 3–28 days. this material is often used for body tissue with low mechanical or shearing force and rapid healing time. plain gut – polyfilament. description: maintains original strength for 7–10 days and full degradation occurs in 10 weeks. advantages/disadvantages: excellent elasticity allowing for adaptation to tissue swelling. passes through the skin with very little tissue trauma occurrence. poor handling and high tissue reactivity causing quick loss of tensile strength. common use: best used in rapidly healing tissues with good blood supply i.e. mucosal tissues. chromic gut – polyfilament description: maintains original strength for 21–28 days and full degradation occurs in 16–18 weeks. advantages/disadvantages: excellent elasticity allowing for adaptation to tissue swelling. passes through the skin with very little tissue trauma occurrence. improved handling and decreased tissue reactivity due to chromic salt coating. common use: skin closure (face), mucosa, genitalia. fast gut – polyfilament description: treated with heat to further break down protein and allow for more rapid absorption in bodily tissues. tensile strength less than a week (3–5 days). advantages/disadvantages: excellent elasticity allowing for adaptation to tissue swelling. passes through the skin with very little tissue trauma occurrence. common use: advised for skin closure only generally on the mucosa or face. synthetic absorbable: includes polyglactic acid, polyglycolic acid, poliglecaprone, polydioxanone and polytrimethylene carbonate. among these are monofilaments, polyfilaments and braided sutures. in general synthetic materials will keep tensile strength for longer due to less local tissue inflammation. poliglecaprone – monofilament (monocryl, monocryl plus, suruglyde) description: copolymer of synthetic materials. loses tensile strength quickly; sixty percent lost in the first week. all strength lost within 3 weeks. advantages/disadvantages: high tensile strength, excellent elasticity, excellent cosmetic outcomes, decreased hypertrophic scarring, minimal tissue reaction, good knot security originally, however the material makes the security unreliable over time, thus it is important to keep ears of material long. common use: advised for subcutaneous and superficial tissue closure. polyglycolic acid - polyfilament (dexon) description: synthetic polymer that loses all tensile strength in by 25 days. either dyed green for visibility or undyed. advantages/disadvantages: minimal tissue reaction, good tensile strength, good handling, but poor knot security. common use: subcutaneous tissue. polyglactin 910 - polyfilament (vicryl) description: loss of all tensile strength in 28 days. advantages/disadvantages: minimal tissue reaction, good tensile strength, good knot security, common use: subcutaneous tissue, skin closure (avoid dyed vicryl on face), polyglactin 910 irradiated - polyfilament (vicryl rapid) description: sourced as vicryl is with irradiation to break down material for quicker absorption. loss of all tensile strength in 5–7 days. advantages/disadvantages: minimal tissue reaction, good tensile strength, fair good handling and good knot security. common use: scalp and facial laceration closure. polglyconate - monofilament (maxon) description: co polymer product of synthetic materials. loses 75% of the tensile strength after 40 days. advantages/disadvantages: minimal tissue reaction, excellent tensile strength, good handling. common use: subcutaneous use often an alternative to pds due to better handling and slightly superior tensile strength. polydioxanone closures (pds) - monofilament description: loss of tensile strength in 36–53 days. advantages/disadvantages: minimal tissue reaction, good tensile strength, but poor handling. common use: subcutaneous with need of high tensile strength (abdominal incision closure). non-absorbable these sutures hold greater tensile strength for longer periods of time and are not subject to degradation. they are appropriate for tissues with a high degree of mechanical or shear force (tendons, certain skin location). they also supply the operator with greater ease of use due to less thread memory. natural: silk - polyfilament (permahand, ethicon; sofsilk, covidien) description: surgical silk is a protein derived from silkworms that is coated to minimize friction and water absorption. advantages/disadvantages: this material has good tensile strength, is easy to handle and has excellent knot security. however, it is rarely used internally due to its significant tissue reaction which causes loss of tensile strength over months. common use: due to advancements in sutures, there is no longer indication for use of surgical silk. however, it is still commonly used in dentistry for mucosal surfaces or to secure surgical tubes on the bodies surface. synthetic: includes nylon, polypropylene and surgical steel all of which are monofilaments with great tensile strength. nylon - monofilaments (dermalon, ethilon) description: polyamide advantages/disadvantages: excellent tensile strength. however, poor handling and poor knot security due to high material memory. common use: excellent for superficial skin closure due to minimal tissue reactivity. it is the most commonly used skin suture due to its excellent adaptability to potentially expanding tissues (edema). nylon - polyfilaments (nurolon, surgilon, supramid) description: polyamide advantages/disadvantages: excellent tensile strength, increased usability, and increased knot security as compared to its monofilamentous counterpart. however, it's polyfilamentous characteristics is said to increase risk of infection. common use: soft tissue, vessel ligations and superficial skin (specifically facial lacerations). braided polyester – polyfilament (ethibond, dagrofil, synthofil, premicron, synthofil) description: made from polyethylene terephthalate, there are various brands and configurations of this type of suture. many are braided, coated in silicone and dyed for visibility. advantages/disadvantages: good handling, good knot security and high tensile strength due to low tissue reactivity. however, this suture can create more tissue trauma when passing through the skin and is more expensive than its counterparts common use: rare, pediatric valvular surgery, alternative to surgical steel for orthopedic surgery due to superior handling. polybutester – monofilament (novafil) description: a copolymer of polyester. advantages/disadvantages: low tissue reactivity, good handling, high tensile strength that is greater than most other monofilaments, good elasticity during increasing edema. common use: rare, tendon repairs, plastics (pull out subcuticular stitch) surgical steel description: synthetic mixture of multiple alloys. advantages/disadvantages: tensile strength is exceptional with very little tissue reactivity, thus maintaining minimal degradation over time. this suture material has very poor handling. common use: orthopedics, sternum closure. during the first dressing, redon's drain was removed and the sutures were checked (surgical suture) sizes suture sizes are defined by the united states pharmacopeia (u.s.p.). sutures were originally manufactured ranging in size from #1 to #6, with #1 being the smallest. a #4 suture would be roughly the diameter of a tennis racquet string. the manufacturing techniques, derived at the beginning from the production of musical strings, did not allow thinner diameters. as the procedures improved, #0 was added to the suture diameters, and later, thinner and thinner threads were manufactured, which were identified as #00 (#2-0 or #2/0) to #000000 (#6-0 or #6/0). modern sutures range from #5 (heavy braided suture for