DK153365B - SURGICAL SUSPENSION - Google Patents

Description

The present invention relates to a surgical suture with improved knot wear properties during attraction and with reduced tissue tension. The surgical suture comprises a polyfilament polymer strand with a thin, lubricating coating.

The surgical suture of the invention is characterized in that the coating consists of a lubricating bioabsorbable copolymer containing polyoxyethylene blocks and polyoxypropylene blocks for ease of knot slipping under attraction and manageability, which bioabsorbable copolymer has a molecular weight of C.

The lubricating coating constitutes from 0.1 to 25% by weight of the uncoated string forming the suture, thereby reducing both jerk and friction sufficiently that a raw ribbon knot can be moved on the suture with control of a wound edge.

Surgical sutures according to the invention are used for closure of a wound in living tissue, whereby the wound edges in living tissue are sutured with a surgical suture having the above-described lubricating coating, the suture is tied into a raw ribbon knot, the raw ribbon knob is slid down during attraction, thus approaching the tissue at a desired location, placing additional strokes on the raw ribbon knot, and in less than ca. 48 hours, the lubricating absorbable copolymer is bioabsorbed and removed from the suture, increasing the knot security and leaving the absorbable surgical suture in the living tissue until the suture strand is absorbed by the living tissue during the healing process, the suture providing useful tissue retention strength and at least 15 days. the absorption is substantially complete within 90 days or the non-absorbable surgical suture is left in the living tissue, thereby enhancing it.

Among the more important handling characteristics of the surgical sutures herein are those associated with knot wear during attraction. One technique that is frequently used is to bind a raw ribbon knot, which can be slid down under attraction from an outer point where the knot is first bonded, to abut the tissue at the desired density. The knot is positioned so that it holds with a degree of strength selected by the surgeon for the particular case, and then further strokes are bonded to the first stroke of the raw ribbon knot. In some cases, the first stroke is a double stroke followed by a single stroke to form a surgical node with additional strokes to form additional raw ribbon knots on top as needed.

In contrast to the lightweight placement is the need for knot security. While it is desirable that it is easy to tie a knot, it is imperative that the knot last for an acceptable period of time without slipping.

Some suture materials are so smooth that a knot very easily slides down and often easily goes up. Other sutures are of materials where the knot tends to "lock" or refuse to slide down during attraction, making it difficult to apply the strokes to the tissue. In the latter case, only a few knocks are required to secure the knot, and knot security is no problem. Nodes in constantly moving tissue, such as near the heart, are much more likely to be dissolved than nodes in resting tissues, such as nodes that hold a wound together within a plaster bandage.

U.S. Patent No. 2,734,506 discloses poly (alkyl) methacrylate as a coating for silk sutures as well as the use of a hot dip coating system.

US Patent No. 3,297,033 discloses synthetic surgical sutures of polyglycolic acid, wherein the fiber surfaces may be coated with a silicone, beeswax or the like to modify handling or rate of absorption.

SE Patent Specification No. 425,834 discloses surgical sutures with improved knot wear properties, consisting of a thin filament polymer strand having a thin, lubricating coating consisting of an absorbable film-forming polymer, an absorbable lubricant, and an absorbable hydrophobic material. The surgical sutures according to the Swedish presentation are thus coated with a three-component coating composition.

According to the present invention, the lubricating coating consists of one component, namely a bioabsorbable copolymer containing polyoxyethylene blocks and polyoxypropylene blocks.

The coating used according to the invention is absorbed very quickly after the introduction of the suture into the body, ie. already within a few days, while the coating composition used according to the Swedish disclosure is absorbed significantly slower, namely over several months.

Coating, staining and conditioning of surgical sutures with polymeric materials in general is well known. Silicones, waxes, polytetrafluoroethylene and other polymers have been used.

However, there is a continuing need for specific coating materials with specific advantages for producing sutures with improved properties.

The sutures of this invention, which have excellent knot-slip properties during tightening and reduced tissue stretching, comprise a polyfilament polymer strand with a thin, lubricating coating of a lubricating, bioabsorbable copolymer. The lubricating copolymer contains polyoxyethylene blocks and polyoxypropylene blocks which facilitate knot wear during attraction and manageability, which bio-absorbable copolymer has a molecular weight such that it is paste-like solid at 25 ° C.

In one embodiment of the invention, the lubricating, bioabsorbable copolymer has the formula

1 2 where one of the symbols R and R is methyl and the other hydrogen and n and m are sufficiently large for the compound to be paste-like solid at 25 ° C, R is the remainder of a relatively low molecular weight reactive hydrogen compound, with from 2 to 6 reactive hydrogen atoms and with a maximum of 6 carbon atoms, and c is the number of reactive hydrogen atoms in the compound forming R.

In another embodiment, the polymer strand is a tissue-absorbable polymer which is subject to hydrolytic degradation to non-toxic, tissue compatible absorbable components and which has glycolic acid ester bonds. In yet another embodiment, the tissue-absorbable polymer is polyglycolic acid.

In a further embodiment, the polymer strand is selected from silk, cotton, nylon, a non-absorbable polyester, polypropylene and polyethylene.

The lubricating coating constitutes 0.1-25% by weight of the non-coated string, calculated on the weight of the non-coated string forming the suture, with both jerk and friction reduced sufficiently for a raw ribbon knob to move at the suture with the control of a wound edge.

In a method of closure of a wound in living tissue, the wound edges of living tissue are sutured with the surgical suture provided with the above-described lubricating coating, the suture is tied into a raw ribbon knot, the raw ribbon knot slid down as it approaches. woven in a desired location, additional strokes are applied to the raw ribbon knot, and in less than approx. 48 hours, the lubricating absorbable copolymer is bioabsorbed and removed from the suture, increasing the knot security and leaving the absorbable suture in the living tissue until the suture strand is absorbed by the living tissue during the healing process, providing the suture with a useful tissue retention strength and at least 15 days. is substantially complete within 90 days or the nonabsorbable surgical suture is left in the living tissue, thereby enhancing it.

Absorbable polyglycolic acid sutures are described in U.S. Patent No. 3,297,033, cited above. Other synthetic absorbable sutures absorbed by living tissue can be coated with excellent results. Currently, the absorbable sutures accepted in the market are those in which degradation or absorption in tissue is caused by the hydrolytic degradation of glycolic acid ester bonds. Such materials ^ are currently sold under the trademarks "Dexon1

^ and "Vicryl

However, the present invention may also be used in conjunction with other synthetic absorbable sutures, both known and future.

With synthetic absorbable sutures, the coating problem becomes difficult to achieve better knot wear properties during attraction due to the requirement that the coating be non-toxic and absorbable.

Non-absorbable sutures are sutures that are resistant to biodegradation in living mammalian tissues and remain in the tissue as a foreign body unless they are surgically removed (e.g., skin sutures) or ejected. Non-absorbable sutures maintain their strength in living mammalian tissue for a long time, often throughout the individual's entire life. Non-absorbable sutures used to close skin ulcers with the knot located above the skin surface are removed by the surgeon at an appropriate time in the healing process. In cases where the knot of the nonabsorbable suture lies deep in the living tissue and must remain there indefinitely, the present lubricant is absorbed from the nonabsorbable suture of less than ca. 48 hours, and when the lubricating effect ceases, knot safety is increased.

Non-absorbable sutures are typically silk, cotton, nylon, a non-absorbable polyester ("Dacron'1

,, polypropylene, polyethylene or flax. Even metals such as stainless steel, such as monofilament or twisted or braided, or tantalum or platinum have been used.

By the terms absorbable or bioabsorbable used in connection with the coating is meant a coating which, by hydrolytic or enzymatic degradation or by its inherent properties, has such molecular weight and solubility properties that it is absorbed from the surface of the suture and eliminated by the individual either unchanged or in hydrolyzed or degraded state.

The lubricating coating not only contributes to enhancing the knuckle wear properties during attraction, but increases the smoothness and flexibility of the sutures so that they can be more easily pulled through the skin and other tissues when applying the suture. This reduction in friction is called reduced tissue tension. The coating, which contributes to reduced tissue tension and which has a lubricating effect when applying the knot, also causes the knot to slide more easily.

Another unexpected and not obvious advantage of the present lubricant over trash is that the lubricating copolymers are absorbed from the suture over a few days, thus increasing the knot security as the wound heals.

The absorbable coating is one or more of a group of compounds having polyoxyethylene blocks and polyoxypropylene blocks in their structure. To simplify the description of these compounds, they are described and considered as having only two or three blocks in the chain. However, it should be understood that there may be non-significant amounts of polyoxypropylene present in the polyoxyethylene block and smaller amounts of polyoxyethylene may be present in the polyoxypropylene block. The manufacturing methods show that there may be, and probably are, such minor admixtures present in the chain. The commercially available grades are acceptable and have low and acceptable toxicity.

The present lubricants can be illustrated by the formula

wherein one of the symbols R and R is methyl and the other is hydrogen, and n and m are sufficiently large for the compound to be paste-like solid at 25 ° C, R is the remainder of a relatively low molecular weight reactive hydrogen compound having from 2 to 6 reactive hydrogen atoms and having a maximum of 6 carbon atoms, and c is the number of reactive hydrogen atoms in the compound forming R. The compounds which are at least paste-like at 25 ° C are preferred because they adhere better to the synthetic one. , absorbable polyfilament suture. There is no sharp demarcation, but in general the efficiency of the materials increases, the more paste-like or solid they become.

The lubricating bioabsorbable copolymers are often classified as surfactants since the polyoxyethylene blocks are predominantly hydrophilic and the polyoxypropylene blocks are predominantly hydrophobic. The materials have been marketed by Wyandotte Chemical Company, Michigan, USA, under the trademark "Pluronic

"with the formula

where x, y and z are integers, "Reverse Pluronic

with the formula

where n, m and o are integers, and "Tetronics" of the formula

where R 1 is

where q and r are integers.

For the purposes of the present invention as synthetic absorbable suture lubricants, the values of x, y, z, n, m, o, q and r are of such magnitude that the lubricants are paste-like solid at 25 ° C.

The pastes are opaque, semi-solid with melting points above room temperature, preferably above ca. 40 ° C.

The materials described above "Pluronic

"are particularly useful in the present invention.

The formulation of certain commercially available products is approximate as shown in the following Table I.

Since all the compositions are mixtures, all values are approximate and the values are somewhat rounded.

Table I

Table I (continued)

II

Usually "Pluronic *

"having a molecular weight in the range of about 4750-16,250 waxy solids. The polyoxypropylene moiety has a molecular weight of 950-4000 and a polyoxyethylene content of about 60-80%.

The pastes usually have a total molecular weight in the range 3500-5700 with a polyoxypropylene molecular weight in the range 1750-6500 and a polyoxyethylene content of 30-50%. The transitions from wax to paste to liquid are not sharp.

The low toxicity of the polyoxyethylene-polyoxypropylene compounds of this invention is shown in the following Table II.

Table IX Toxicity “Pluronic

"Total Physical LD50 (Ag) No. Molecular Weight Property in Mice F-38 5000 Wax> 5 F-77 6600 Wax 4.2 F-87 7700 Wax 3.75 F-68 8350 Wax ^> 5 F-88 10,800 Wax ^ > 5 F-127 12,500 wax 2.25 F-98 13,500 wax> 5 F-108 14,400 wax 1.25 P-65 3400 paste 0.83 P-84 4200 paste 0.4 P-85 4600 paste 0.53 P -94 4600 paste 0.6 P-103 4950 paste 1.4 P-104 5850 paste 0.75 P-123 5750 paste 2.7 P-105 6500 paste 3

The suture string is used as a weight basis in determining the amount of material applied to the synthetic absorbable polymer strand in forming the absorbable surgical suture.

The amount of the lubricating bioabsorbable copolymer is 0.1-25% by weight of the uncoated strand, based on the weight of the uncoated strand forming the suture. It is not necessary for the coating to be continuous as a discontinuous coating on the surface helps to reduce friction and jerking. A greater amount can be used if the lubricating, bioabsorbable copolymer enters the strand, the different filaments themselves being partially or completely covered.

The wide area of the weight of the coating allows the sutures of the present invention to be adapted for a variety of applications. Since the string to be coated to form the suture may vary considerably in surface unevenness due to the mechanical structure, i.e. braided or twisted etc ^, or if the suture is made from filaments which are of less than 2 denier per. filament for more than 6 denier per filament, the finer filament providing a smoother surface, and since the filaments can be stretched after the suture is made or by heat treatment, the surface irregularity may in principle vary. The smoother the surface, the lesser amount of lubricating, bioabsorbable copolymer is required to achieve analogous degree of slip.

The various surgical methods used and the desired degree of lubrication intervene. For any given knot type, a greater amount of lubricant which, by a special technique, facilitates knot slip during attraction, will also facilitate knot retraction or slip, which is called knot safety. In some surgical methods, it is highly desirable that the knot has a very free slip during attraction, although the knot then slides back slightly.

A surgeon, when tying surgical knots, will encounter the interplay between knot tying method and sliding ease. If a suture is relatively well lubricated, the surgeon may use a raw ribbon knob, which is easily slid down during attraction, with additional raw ribbon strokes to achieve knot safety. On the other hand, if the suture is less well lubricated, the surgeon may use a double half-stitch or other knot type which can be more easily moved to slide into position, after which the double half-stitch can be pulled to form a raw ribbon knot, or further placement can be made. knock down the knot to obtain adequate knot security. Thus, the surgeon can either adapt his knot technique to a particular suture, or he can use sutures whose surface smoothness is best suited to the technique the surgeon wants to use. In general, this is a mutual adjustment. The surgeon tries to obtain a suture whose properties match those of his will, and then he adapts his knot tying technique to the sutures he has at that time. Some surgeons make very successful stainless steel wire knots using a knot tying technique adapted to such wire that has very poor slip-off properties during attraction. Others prefer a more well-oiled suture, which slides down much easier during attraction.

Since knot wear ease during attraction and knot safety is in contradiction, it is necessary for the surgeon to use additional strokes or knots which will last under the particular conditions of a given surgical procedure. By changing the amount of the lubricating, bioabsorbable copolymer, the attrition properties during attraction can be modified to match the properties desired by the surgeon.

The time of use of the nodes can be completely varied.

Because the present lubricating, bioabsorbable copolymer is removed from the living tissue suture as the lubricant is removed, the knot security is increased and after 48 hours or less the knot security is significantly increased.

The surgical requirements are highly variable and different coating weights allow the sutures to be adapted to different conditions.

If the surgeon wants a better lubricated suture, a larger amount of the lubricating, bioabsorbable copolymer is generally used, and vice versa, if the surgeon is willing to accept a slightly reduced knot slip during attraction and slightly reduced tissue tensile properties in favor of greater knot security, the amount of excess used is diminished. to achieve this special compromise.

Using 2-8% of the lubricating, bioabsorbable copolymer, usually an acceptable compromise between knot end slippage during attraction and knot security is obtained.

When using approx. 5% by weight "Pluronic" F-68 achieves a preferred compromise between the requirements for chewing wear properties and knot safety for twisted or braided polyglycolic acid sutures of 2-6 denier per minute. filament.

In the following examples, the effect of certain different coatings and their amounts used are elucidated under certain conditions.

Example 1

Demolition and jerk test

A set of 2/0 USP XIX polyglycolic acid sutures (diameter maximum 0.339 mml braided or twisted by 2 denier extrusion per filament is coated with 7 different amounts of "Pluronic

"F-68, leaving one suture blank, ie without overcoat. Then a knot slip test is performed.

In this test, the suture is tied with a raw ribbon knot around a cylinder with a circumference of 10 cm. The resulting loop is pulled off and placed in the jaws of the testing machine. The knot is slid down by drag. at the original free end in a test machine / detecting the move on a card / as the knot slides down the suture. There is jerk or variation in knot slip tension during knot sliding down the suture. This is graphically depicted.

Of a series of tests with different amounts of coating, the fraction of 10 tests at which the maximum knot slip force is within the particular ranges indicated in the following Table III is indicated. All of the knots on coated sutures slip throughout the entire length of the suture without breaking. The knot breaking strength of the suture string is in the range of 3.18-3.63 kg. On the uncoated suture, the knot goes up and there is a fracture of the suture in 9 out of 10 tests.

Table III

Knot slip on 2/0 polyglycolic acid sutures with "Pluronic ®" F-68 lubricant

Coatings -'- Fractions in experiments where the maximum resistance is: amount% O ^ 0.45 0.45 ^ -0.91 0.91 ^ -1.36 1.36-1.81 l, 81v-2, 27 2.27 ^ 2.72 2.72-3.18 kg 0.0 fracture before nodal slip in 9 of 10 tests 1.9 2/10 2/10 4/10 2/10 2.8 2/10 3/10 2/10 3/10 3.9 1/10 1/10 4/10 2/10 2/10 5.0 3/10 2/10 2/10 2/10 1/10 6.2 2/10 3/10 2/10 3/10 7.4 3/11 1/11 4/11 3/11 8.0 5/10 2/10 3/10

The maximum force for knot wear decreases evenly with increasing volumes. Smaller coating amounts on another suture show: 0.51 1/10 2/10 2/10 3/10 2/10 1.09 5/10 1/10 3/10 1/10 1.53 5/10 1/10 1 / 10 1/10 1/10 1/10

In these coatings, the suture is passed through a solution of "Pluronic" F-68 in chloroform at a concentration of about the double percentage of the coating on the suture.

With other suture structures and other sizes, the relative knot wear ease may be greater or less for the same amount of coating or vice versa, the amount of coating may be adjusted so as to obtain the desired knot wear values.

The amount of "Pluronic" in the solvent can be varied and solvents other than chloroform can be used.

Other organic solvents such as methyl alcohol, ethyl alcohol, isopropyl alcohol, methylene chloride, hot xylene (about 60 ° C), tetrahydrofuran, acetone, dimethylformamide, dimethyl sulfoxide, mixtures thereof and other similar solvents for the lubricant may be used for coating. In another applicable coating technique, a strand is moved in a stream of solution, after which the excess amount is allowed to drip.

A small amount of water increases the solubility of the lubricants and contributes to coating, but the duration of the suture's contact with water should be as small as possible. Thus, if moisture is present in the coating system, the sutures must be dried immediately.

Generally, it is more convenient to use the solvent coating system at an uptake of less than 10% and to use a heated die for uptake of more than 10%, i.e., pull the wire through a heated calibrated opening with the coating agent.

Example 2

A number of experimental studies are carried out using a coating of the two commercial "Pluronic1

* F-68 and F-127 at 6 denier per filament twisted or plaited absorbable polyglycolic acid sutures of size 2/0. The sutures are coated with a solution

of "Pluronic11— in chloroform. The concentration of" Pluronic

in the solution used for coating is approximately twice the size obtained on the suture. A solution containing approx. 2.8% "Pluronic1

* F-68 in chloroform gives approx. 1.4% "Pluronic" F-68 on the suture. The concentration can be adjusted to achieve any desired. The strand to be coated is twisted or plaited to a size 2/0 suture using a 6 denier extrusion of polyglycolic acid. filament. An uncoated suture string of the same batch is used as a control. A standard "ATLAB Yarn Friction Tester" model; CS-151-026, from Custom Scientific Instruments, Inc. Whippany, New Jersey with a two-channel amplifier printer is used to record the voltage in the string, which is fed into the test apparatus and exits the yarn tester. The jerk factor is the ratio between the maximum tensile (T3) and the supply voltage (T1) minus the ratio between the minimum tensile (T2) and the supply voltage, ie.

The friction values are the values for T2 for starting slip.

The values of particular interest are the ratios and the percentage reduction. With other types of test apparatus, the numerical values can be changed, but the relative conditions such as index for improvement are analogous.

In this test, a non-cut strand, coated as described above, is used. For use as a suture, such a string is cut to appropriate lengths, provided with needles, packaged and sterilized using conventional techniques. Friction and r ^ k are measured more easily at continuous lengths.

Reduction in static friction, jerk and coefficient of friction are given for typical coating quantities and sutures in the following Table IV.

The percentage reduction is calculated on the basis of the average of the two experiments where no "Pluronic" coating has been used, ie. eg.

where Fav is the average of static friction in Experiments 1 and 2 without “Pluronic

"coating, and Fg is the static friction in the individual experiments.

Table IV

Polyglycolsyresutur

Tests for knot security depend on the exact knot tying technique.

In a representative oak, typical series of knot safety experiments with size 2/0 polyglycolic acid sutures with 2 deniers per filament and with a 4.79% "Pluronic

In "f-68 coatings and various knots, the force i.kg is measured by which knots slip up, or breakage occurs, without the knot sliding. The following results are obtained:

Example 3

A series of experiments involving non-coated sutures are carried out with solutions of "Pluronic" bioabsorbable lubricating copolymers in chloroform by the procedure described in Example 2. The results obtained with respect to friction and friction with a variety of polymers and concentrations thereof are set forth in the following Table V.

Table V

Polyglycolic Acid Suture "Pluronic" ® - Size 2/0 ~ 6 Denier Per filament

Table V (continued)

Polyglycolic Acid Suture "P'luroriib1" ^ size 2/0 6 denier per '.' f xlairient

Example 4

A twisted or braided polyglycolic acid strand of such size to form a 2/0 USP suture is immersed in a 10% solution of "Pluronic®" F-68 in chloroform and dried. The recording amounts to approx.

5% by weight of the string itself.

The dried coated strand is cut into 137 cm pieces which are provided with needles, packaged, sterilized and dried according to known methods.

The sutures thus made are used for surgical procedures. When used for the contraction of wound tissue, a suture is placed in a suitable location and tied with a raw ribbon knot. The knot slides easily while contracting the wound edges with the density desired by the surgeon. The suture exhibits poor tissue tension and excellent knot wear during tightening. When a node is in the desired end position, three additional raw band strokes are applied to secure the node. From knots that are deep in tissue, the lubricating, bioabsorbable copolymer is removed from the suture surface within 48 hours, providing additional nodal safety. The suture itself retains tissue retention strength for at least 15 days and is substantially absorbed within 90 days.

Although crude ribbon knots have been used in the examples and experiments, slight knot wear and reduced tissue tension are required for most suture applications and for knot retention. The amount of coating and the relative values of nodular wear and reduced tissue stretching can be varied to meet the requirements of a particular surgical situation.

The coated sutures are provided with needles, packaged and sterilized according to known methods.

Example 5

Friction and rumor test

A set of 2/0 USP XIX twisted or braided silk sutures (diameter maximum 0.339 mm) is coated with 5 volumes of "Pluronic" F-68 and 12 volumes of "Pluronic®" F-127.

For comparison, 4 blind trials are performed on sutures of the same batch without the use of coatings, and an average of these 4 is used for comparison values.

In comparison, 5 experiments are also performed using a commercial silicone-coated silk suture, cf. U.S. Patent No. 3,187,752.

In these coatings, the suture is passed through a fine solution of "Pluronic ®" in chloroform at a concentration of approx. the double percentage of the coating desired on the suture on which it is air dried.

A standard "ATLAB Yarn Friction Tester", model CS-151-026, from Custom Scientific Instruments, Inc., Whippany, New Jersey, with a two-channel amplifier printer is used to record the voltage in the string that is fed into the test apparatus and exits of the yarn tester. The jerk factor is the ratio of the maximum tensile (T-j) to the supply voltage (T ^) minus the ratio of the minimum tensile (T2). and the supply voltage, ie. The friction values are the values of T2 for starting slip.

The values of particular interest are the ratios and the percentage reduction. With other types of test apparatus, the numerical values can be changed, but the relative conditions such as index for improvement are analogous.

In this test, a non-cut strand, coated as described above, is used. For use as a suture, such a string is cut to appropriate lengths, provided with needles, packaged and sterilized using conventional techniques. Friction and jerk are measured more easily on continuous lengths.

Reduction in static friction, jerk and coefficient of friction is given in the following Table VI.

Table VI

Size 2/0's toy suture

Table VI (continued) Size 2/0 silk out

With other suture designs and sizes, the knot wear ease can be greater or less for the same amount of coating, or conversely, the amount of coating can be adjusted to achieve the desired knot wear values.

The amount of “Pluronic

The solvent may be varied and solvents other than chloroform may be used.

Other organic solvents such as methyl alcohol, ethyl alcohol, isopropyl alcohol, methylene chloride, hot xylene (about 60 ° C), tetrahydrofuran, acetone, dimethylformamide, dimethyl sulfoxide, mixtures thereof and other similar solvents for the lubricant may be used for coating. In another applicable coating technique, a strand is moved in a stream of solution, after which the excess amount is allowed to drip.

A small amount of water increases the solubility of the lubricants and contributes to coating.

Generally, it is more appropriate to use solvent-based drawing system at an uptake of less than 10%. and use a heated tray "heated die" for recordings in excess of approx. 10%.

Example 6

Size 2/0 twisted or braided nylon sutures

Using the procedure described in Example 1, experiments with size 2/0 twisted or braided nylon suture are performed. The reduction in friction and jerk factors is given in the following Table VII. Both uncoated sutures from the same lot and commercial silicone coated nylon suture are used for comparison.

The reduction in jerky is particularly noteworthy.

Table VII

Example 7

Size 2/0 twisted or braided "Dacron sutures /

Using the method described in Example 1, experiments with a size 2/0 twisted or braided polyester suture ('* Dacron' '). The reduction in friction as well as the jerk factors are given in the following Table VIII.

Both uncoated suture ffa same portion and silicone coated suture are used for comparison. An average of the uncoated suture experiments is used as a basis for illustrating the improvement achieved.

Table VIII

Size 2/0 ”Dacron11 Suture

The data given in the examples is illustrative. Reductions in friction and improvement in jerking are achieved with all suture sizes. With different materials and constructions, results can vary.

The amount of coating and the knot wear ease can be varied to achieve the results desired by the surgeon.

For sutures, either absorbable or non-absorbable, where capillarity is a problem, a coating of a phosphatide, preferably purified lecithin, such as described in U.S. Patent No. 2,576,576, can be used to reduce capillarity and friction in connection with this coating as a further friction reductant. Lecithin causes tissue irritation under some conditions, especially if it is not clean.

Example 8

A twisted or braided silk suture string of such size as to form a 2/0 USP suture is immersed in a 10% solution of "Pluronic®" f-68 in chloroform and dried. The recording is approx. 5% by weight of the weight of the string itself.

The dried coated strand is cut into 137 cm pieces, supplied with needles, packaged, sterilized and dried according to conventional methods.

The silk sutures thus made are used in surgical procedures. When used for the contraction of wound tissue, a suture is placed in a suitable location and tied with a raw ribbon knot. The knot slides easily while contracting the wound edges with the density desired by the surgeon. The suture exhibits poor tissue traction and excellent nodal wear during laceration. When a node is in the desired end position, three additional raw band strokes are applied to secure the node. From knots that are deep in tissue, the lubricating, bioabsorbable copolymer is removed from the suture surface within 48 hours, providing additional nodal safety.

When a crude band knot is removed from experimental animals after 48 hours without further impact, it exhibits remarkably greater knot security than immediately after placement.

In human tissue, knot safety is increased as far as it can be ascertained as the bioabsorbable, lubricating coating is absorbed into the tissue.

Although in the examples and experiments, raw ribbon knots are used, there is a need. slight knot wear and reduced tissue tension in most suture applications as well as knot retention. The amount of coating and the relative values of nodular wear and: xeduced tissue stretch can be varied to meet the requirements of a particular surgical situation.

The coated sutures are provided with needles, packaged and sterilized according to known methods.

Claims (3)

A surgical suture with improved knot slip properties during tightening and with reduced tissue tension, comprising a thin filament polymeric filament strand characterized in that the coating consists of a lubricating bioabsorbable copolymer containing polyoxyethylene blocks and polyoxypropylene blocks. facilitating knot wear during attraction and manageability, which bioabsorbable copolymer has a molecular weight such that it is paste-like solid at 25 ° C. Suture according to claim 1, characterized in that the lubricating, bioabsorbable polymer has the formula 1 where one of the symbols R and R is methyl and the other hydrogen and n and m are sufficiently large for the compound to be paste-like solid at 25 ° C, R is the remainder of a relatively low molecular weight reactive hydrogen compound, with from 2 to 6 reactive hydrogen atoms and with a maximum of 6 carbon atoms, and c is the number of reactive hydrogen atoms in the compound forming R. Suture according to claim 1 or 2, characterized in that the lubricating coating constitutes from 0.1 to 25% by weight of the uncoated string forming the suture, in that both jerking and friction are sufficiently reduced that a raw ribbon knot is movable on the suture with control of a wound edge.