NZ192138A

NZ192138A - Elastomeric surgical suture

Info

Publication number: NZ192138A
Application number: NZ192138A
Authority: NZ
Inventors: A A Gertzman; M T Gaterud
Original assignee: Ethicon Inc
Priority date: 1978-12-08
Filing date: 1979-11-15
Publication date: 1984-05-31
Also published as: DE2949181C2; AR222361A1; CA1203137B; HK30083A; GB2038704B; PT70564A; PH22728A; IN151798B; ES8101387A1; GB2038704A; SG10283G; AT370999B; IT7950997A0; NL7908845A; CA1141915A; AU5319779A; DE2949181A1; MX152227A; ATA776179A; IL58897A

Description

» t -r~r: .T" Pnor&y •> ■ ^ ^ Complete Specification Filed: • claEs: W!h!^P°3YMAy39&4 Publication Date: .. .M. I • * iw« •»»'>** /<PSS P.O. Journal, Mo: .» • »•••• a ■ ■ ■ • * 9l« ^ r% <rc ff15??? SI • put 4^ ^ ii« Jhfc §£JsB $ Patents Form No. 5 Numbor PATENTS ACT 1953 Dtitod- COMPLETE SPECIFICATION Improvements in or relating to a suture //We ETHICON, INC., a New Jersey corporation of the United States of America, of Route 22, Somerville, New Jersey, United States of America do hereby declare the invention for which //we pray that a Patent may be granted to me-/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - 1 - (followed by page la) 1 9 W.McC & ELASTOMERIC SURGICAL SUTURES COHPRIGING-SEGMENTED COPOLYETIIER/EGTERC CROSS REFERENCE ghio application io a Continuation-in-Part of Serial Ne-«—967 i 656 /—filod Dooombor 8/—1978 / now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to surgical sutures, and more particularly, to soft, elastomeric sutures having unique handling and knot tying characteristics. The sutures may be prepared from segmented copolyether/. 10 esters or other elastomeric polymers.

Many natural and synthetic materials are presently used as surgical sutures. These materials may be used as single filament strands, i.e, monofilament sutures, 15 or as multifilament strands in a braided, twisted or other multifilament construction. Natural materials such as silk, cotton, linen, and the like, of course do not lend themselves to the fabrication of monofilament sutures and are accordingly generally used in one of the 20 multifilament constructions.

Synthetic materials which are extruded in continuous lengths can be used in monofilament form. Common synthetic monofilament sutures include polyethylene 25 terephthalate, polypropylene, polyethylene, and nylon. Such monofilament sutures are preferred by surgeons for many surgical applications due to their inherent smoothness and noncapillarity to body fluids. t 9 2 The presently available synthetic monofilament sutures all suffer to a greater or lesser degree from one particular disadvantage, that is inherent stiffness. Besides making the material more difficult to handle and use, suture stiffness can adversely affect knot tying ability and knot security. It is because of the inherent stiffness of available monofilament sutures that most larger suture sizes are braided or have other multifilament constructions with better handling flexibility.

Monofilament sutures of the prior art are also characterized by a low degree of elasticity, the most elastic of the above-mentioned synthetics being nylon which has a yield elongation of about 1.7 percent and a visco-15 elastic elongation of about 8.5 percent. The inelasticity of these sutures also makes knot tying more difficult and reduces knot security. In addition, the inelasticity prevents the suture from "giving" as a newly sutured wound swells, with the result that the suture may 20 place the wound tissue under greater tension than is desirable, and may even cause some tearing, cutting or necrosis of the tissue.

The problems associated with the use of inelastic sutures 25 in certain applications were recognized in U.S. Patent No. 3,454,011, where it was proposed to fabricate a surgical suture composed of Spandex polyurethane. Such sutures, however, were highly elastic with "rubbery" characteristics and did not find general acceptance in 30 the medical profession. 1 is accordingly an object of the present invention tj provitte^a novel soft, limp, monofilament sutur^-ms£e-rial. It is~^skfurther object of this invention to pro-W.McC 35 vide a monofilamerv&^s^ture wvth^a^controlled degree of elasticity to accommoda£ja>i§Hanging wound conditions. It is another obje^t-^r this invervE^bon to provide a new, nonabsorbable suture having a diameter^oifrom about Q^OiT'to 1.0 mm and possessing unique and desii-able ETH-4 6 7 1 C 'J £3; O 3 ^ M ^ physical propog-fadioci-i Thcoo and-other objects will be appamnf tfre ansuing description and claims.

SUMMARY Monofilament sutures of the present invention are characterized by the following combination of physical properties: Yield elongation - from about 2 to 9 percent Visco-elastic elongation - from about 10 to 30 percent Young's modulus - from about 30,000 to 200,000 psi Tensile strength - at least about 40,000 psi Knot strength - at least about 30,000 psi Sutures possessing the above characteristics may be pre-15 pared by melt extruding certain elastomeric polymers such as copolyether/ester polymers to form a continuous filamentary strand, and thereafter drawing the extruded filament to obtain the desired suture properties. Certain copolyether/ester polymers available commercially 20 from E. I. du Pont de Nemours & Co. under the tradename "HYTREL" have been discovered to be suitable starting materials for the preparation of sutures in accordance with the present invention.

Monofilament sutures having physical properties in accordance with the present invention are particularly useful in many surgical procedures where the suture is used to close a wound which may be subject to later swelling or change in position. The combination of low 30 Young's modulus and significant yield elongation provides the suture with an appreciable degree of controlled elasticity under low applied force. As a result, the suture is able to "give" to accommodate swelling in the wound area. The relatively high visco-elastic yield 35 elongation and high tensile strength of the suture allows the suture to stretch during knot tie-down so that the knot "snugs down" for improved tying ability and knot security with a more predictable and consistent knot ETH-4 61 1 4 geometry regardless of variations in suture tying technique or tension.

BRIEF DESCRIPTION OF DRAWINGS 5 Figure 1 is a representative stress-strain curve characteristic of the surgical filaments of the present invention .

Figure 2 is a representative stress-strain curve compar-10 ing filaments of the present invention with monofilament sutures of the prior art.

DESCRIPTION OF PREFERRED EMBODIMENTS The sutures of the present invention are characterized by 15 a combination of physical properties which are unique for monofilament sutures, and which provide the sutures of the present invention with unique and desirable functional properties.

The characteristic properties of the inventive sutures are readily determined by conventional test procedures. Figure 1 illustrates a typical stress-strain or load-elongation diagram for the sutures of this invention. In Figure 1, yield elongation (Ey) is the point at which 25 permanent deformation of the suture begins to take place. So long as the filament is not elongated beyond Ey, elastic recovery is essentially complete. The sutures of the present invention have an Ey with the range of 2 to 9 percent.

Young's modulus is a measure of the slope of the stress-strain curve over the initial portion of the curve extending from the origin. In Figure 1, line a is a drawn tangent to the curve at the origin, and Young's modulus 35 is equal to tan 8. The slope of the curve, and Young's modulus, are seen to be a measure of the resistance to elongation in the initial elastic portion of the curve. The sutures of the present invention are designed to have a significant, but relatively low modulus of 30,000 to Jj A ii 1 200,000 psi, and preferably within the range of 50,000 to 150,000 psi. A modulus within the claimed range provides the correct amount of increasing tension on the suture as the suture is extended toward its yield point 5 (Ey). At lower values of Young's modulus, the suture readily elongates under very low tension to its yield point and the advantages of having a significant yield elongation are lost. At higher values of Young's modulus, filament stiffness becomes the controlling consideration, 10 and the softness and good handling properties of the suture diminish.

The portion of the stress-strain curve extending between Ey and Ev on Figure 1 is the visco-elastic region during 15 which there is considerable elongation and permanent deformation of the suture with only slightly increasing tension. The visco-elastic elongation (Ev) of the sutures of the present invention is controlled to be within the range of from about 10 to 3 0 percent. This 20 property of the suture allows the suture to draw down during knotting to assure good knot security.

As the suture is elongated beyond Ev, the load increases rapidly as indicated in Figure 1. This rapid increase 25 in load imparts a positive feel to the suture which, in the hands of a skilled surgeon, signals when Ev and maximum knot security are achieved. Preferably, the value of Ev is at least 2.5 times the value of Ey in order to provide the surgeon with a broad visco-elastic 30 region in which to work during suture tie-down.

As seen in Figure 1, the load from 0 to Ev elongation is relatively low compared to the breaking load (Sb). Preferably, the breaking load or straight tensile strength 35 is at least 40,000 psi, and the load Sv corresponding to visco-elastic elongation is less than one-third of the breaking load, with the result that the suture may be easily knotted under relatively low forces and without 1 9 6 risk of unintentionally breaking the suture. Knot strength of the suture is preferably at least 30,000 psi.

The breaking elongation (Eb) of the sutures of the pres-5 ent invention are generally within the range of 30 to 100 percent. Although this property is not critical to the performance of the suture since suture elongation in use does not generally exceed Ev, it is preferable that Eb be at least 1.5 x Ev in order to reduce the pos-10 sibility of inadvertently over elongating and breaking the suture during tie-down.

The unique mechanical properties of the sutures of the present invention will be more readily appreciated from 15 Figure 2 where such sutures are compared to nylon and polypropylene sutures of the prior art. Representative physical properties of these three suture materials are given in Table I. Each of these prior art sutures has a considerably higher Young's modulus which results in the 20 characteristic stiffness of these materials. In addition, neither suture has a noticeable Ey or an extended visco-elastic region which characterize the sutures of the invention and impart the desirable properties discussed above.

The mechanical properties of the sutures of the present invention reflected in the relative values of Ev and Ey in combination with the low Young's modulus and high tensile strength are unique in the field of surgical su-30 tures and distinguish the monofilament sutures of the present invention from all prior art materials.

TABLE I Suture property Suture material Polypropylene Nylon This invention Diameter, mils (mm) 12.5 (0.32) 12.8 (0.33) 12.9 (0.33; Tensile strength, psi (Kg/cm2) 58,900 (4,100) 75,200 (5,300) 64,700 (4,500) Elongation to break, % 32.2 40.1 39. 5 Visco-elastic elongation (Ev), % 9.0 8.5 14.8 Yield elongation (Ey), % 1.1 1.7 2.2 Stress at Ey (Sy), psi (Kg/cm2) ,100 (360) 3,600 (250) 2,500 (180) Stress at Ev (Sv), psi (Kg/cm2) ,700 (1,800) 13,200 (930) 9,200 (650) Young's modulus, psi (Kg/cm2) 425,000 (29,900) 221,000 (15,500) 112,000 (7,900) 1 9 8 Sutures having mechanical properties in accordance with the present invention may be prepared from the segmented copolyether/ester compositions disclosed in U.S. Patent No. 3,023,192, incorporated herein by reference, which states in part at Column 2, line 20 et seg.: "The copolyetheresters of this invention are prepared by reacting one or more dicar-boxylic acids or their ester-forming derivatives, one or more difunctional polyethers with the formula: (in which R is one or more divalent organic radicals and £ is an integer of a value to provide a glycol with a molecular weight of between about 350 and about 6,000), and one or more dihydroxy-compounds selected from the class consisting of bis-phenols and lower aliphatic glycols with the formula: (in which £ is 2-10), with the proviso that the reactants be selected so that substantially all of the repeating units of the polyester contain at least one aromatic ring. The resulting ester is then polymerized." The preparation of other related segmented thermoplastic copolymers are described in the following additional references which are also incorporated herein by reference for their teachings in this regard: U.S. Patents Nos. 3,651,014; 3,763,109; 3,766,146; and 3,784,520.

According to the above references, the disclosed segmented thermoplastic copolymers may be cast as films, injection molded to form objects, or melt extruded to form filaments. The products obtained in accordance with these references, however, are characterized by physical properties which are not desirable for surgical sutures.

HO(RO) H P HO(CH0) OH Z Q q £TH-4 6 7 ' ~ 19213 9 In particular, the filaments of the references are rubbery with a very high degree of elasticity as indicated by break elongations in excess of 500 percent. Tensile strengths, on the other hand, are very low, generally less than 8,000 psi. The filaments prepared from co-polyether/esters in accordance with the teachings of these references therefore do not possess the mechanical properties' of the sutures of the invention, and, in fact, are obviously not at all suitable for use as surgical sutures.

The disadvantages of the prior art references are overcome by means of the present invention wherein filaments extruded from certain copolyether/esters are quenched and drawn with the result that the mechanical properties of the filaments are controlled to be within the specific limits discovered to be particularly desirable for surgical sutures.

The segmented copolyether/esters useful in the present invention comprise a multiplicity of recurring long chain ether/ester units and short chain ester units joined head to tail through ester linkages according to the following general formula: 0 0 0 0 II II II II t(O-D-O-C-R-C) (O-G-O-C-R-C - 0), ] (I) a d n The long chain ether/ester units of the polymer are represented by the general formula: O 0 II II ■ -O-G-O-C-R-C (II; wherein G is a divalent radical remaining after the removal of terminal hydroxyl groups from a poly(C2_^g alkylene oxide)glycol having a molecular weight within the range of about 350 to 6,000, and R is a divalent radical remaining after the removal of carboxyl groups from an aromatic dicarboxylic acid having a molecular weight of less than about 300. u i h - 4 ti 7 1 921 The short chain ester units are represented by the general formula: 0 O ii ii -O-D-O-C-R-C- (III) wherein D is a divalent radical remaining after removal 5 of hydroxyl groups from an alkyldiol having a molecular weight of less than about 250, and R is as defined above.

In the above Formula I, a is an integer such that the short chain copolymer segments represented by a comprise 10 from 50 to 90 percent by weight of the total copolymer composition; b is an integer such that the long chain copolymer segments represented by b comprise from 10 to 50 percent of the total copolymer composition; and n is the degree of polymerization resulting in a fiber-15 forming copolymer.

The copolyether/esters represented by Formula I may be melt extruded, quenched and drawn to obtain filaments having physical properties desirable for surgical su-20 tures as above defined. Polymer to be extruded is dried at about 200-220°F in a circulating hot air oven and/or under vacuum in order to remove all traces of moisture and other volatile materials. The polymer is then melt extruded and water quenched in accordance with the con-25 ventional melt spinning techniques for synthetic fibers. The fiber is finally drawn at least about 5X, and usually from about 7X to 9X to achieve molecular orientation .

The preparation of fibers useful as surgical sutures from copolyether/esters in accordance with the present invention is demonstrated by the following examples which are presented by way of illustration and are not limiting of the present invention. The polymers utilized in 35 these examples are copolyether/esters prepared from 1,4-butanediol, dimethyl phthalate, and polytetra-methylene ether glycol (M.W. of about 1,000), and are 11 commercially available from E. I. du Pont de Nemours & Co. under the tradename "HYTREL". The polymer contains intrapolymerized butylenephthalate hard segments (short chain ester units) and polytetramethylene ether terephthalate soft segments (long chain ester units) and has the following general structure as reported in the Journal of Elastomers and Plastics 9_, 416-38 (Oct. , 1977) : oo oo [ 0 - (CH2)4 - 0 - C - - C]al0(CH2CH2CH2CH20)x - C " C]fa (TO (hard segment) (soft segment) wherein a and b are as defined above and x is an integer reflecting the molecular weight of the ether glycol re-actant (x = 14 for M.W. of about 1,000).

In the following examples, physical properties of individual monofilaments were determined on an Instron tensile tester under the following conditions: Crosshead speed (XH) Chart speed (CS) Sample length (GL) Scale load (SL) in/min 10 in/min 5 in 2 lbs/in With reference to Figure 1, Young's modulus is calculated from the slope a of the stress-strain curve in the initial linear, elastic region as follows: • .. , , , . . tan 8 x GL x CS x SL Young's modulus (psi) = XH x XS wherein 8 = the angle indicated in Figure 1 . 2 XS = the cross-sectional area of the fiber, m SL, XH, CS, and GL are as identified above.

Yield stress (Sy) is the load at the point of intersection of lines a and b drawn tangent to the initial elastic region and the visco-elastic region, respectively, of the curve as illustrated in Figure 1. Yield elongation (Ey) is the elongation corresponding to Sy and is read directly off the stress-strain curve. ^21 3 12 Visco-elastic stress (Sv) is the load at the point of intersection of line b with line c drawn tangent to the curve as illustrated in Figure 1. Visco-elastic elongation (Ev) is the elongation corresponding to Sv and is read directly off the curve.

Break elongation (Eb) and breaking tensile strength (Sb) are read directly off the stress-strain curve as illustrated in Figure 1.

EXAMPLE I A sample of copolyether/ester of Formula IV having approximately 40 wt percent soft segments and comprising approximately 51 percent terephthaloyl units, 16 percent 15 units derived from polytetramethylene ether glycol, and 33 percent units derived from 1,4-butanediol was dried four hours at 200°F in a circulating hot air oven and then further dried under vacuum at 100 microns (no heat) for 16 hours. The dry polymer was placed in a one-inch 20 horizontal extruder and extruded through a J/50/1 die at an extrusion temperature of 380°F.

The extrudate was quenched in water at ambient temperature and drawn to a size 2-0 monofilament suture using a 8.8X 25 draw ratio at a temperature of 530°F and with a take-up speed of 485 ft/min. Physical properties of the resulting filaments are given in Table II.

EXAMPLE II A sample of copolyether/ester of Formula IV having approximately 23 wt percent soft segments and comprising approximately 45 percent terephthaloyl units, 4 percent orthophthaloyl units, 20 percent units derived from polytetramethylene ether glycol and 31 percent units derived 35 from 1,4-butanediol was dried and extruded at 400°F as described in Example I. The extrudate was quenched and drawn into a size 2-0 monofilament using a 7.5X draw ratio at a temperature of 450°F and with a take-up speed of - 4 0 V 1 9 13 412 ft/min. Physical properties of the resulting filaments are given in Table II.

EXAMPLE III A sample of copolyether/ester of Formula IV having approximately 18 wt percent soft segments and comprising approximately 41 percent terephthaloyl units, 35 percent units derived from polytetramethylene ether glycol and 24 percent units derived from 1,4-butanediol was 10 dried and extruded at 405°F as described in Example I. The extrudate was quenched and drawn into a size 2-0 monofilament suture using a 6.5 draw ratio at a temperature of 560°F. The take-up speed was 75 ft/min. Physical properties of the resulting filaments are given in 15 Table II. It is noted that the Young's modulus of these filaments exceeded the maximum desirable limit for sutures of the present invention.

EXAMPLE IV Three parts of a copolyether/ester of Example I and two parts of a copolyether/ester of Example III were dry blended to provide a polymer having a total of 30.2 percent soft segments. The blended material was dried in a vacuum oven for two hours at 1-2 mm Hg (no heat), and 25 then heated at 50°C for three hours at 1-2 mm Hg.

The dried mixture was melt blended in a 3/4-inch Brabender extruder with a 25-inch barrel with a 20/1 screw and extruded at 430°F through a 5/32-inch die in a vertical 30 monofilament assembly. The extrudate was water quenched at ambient temperature, pelletized, and again dried as described above for the dry-blended material before extruding into monofilament sutures. A size 2-0 monofilament suture of this material was extruded at 400°F using 35 a 7.9X draw ratio at a temperature of 460°F and a take-up speed of 435 ft/min. Physical properties of the resulting filaments are given in Table II.

LTll-s 6 7 i Q 9 1 7 0 I 1L I J o 14 EXAMPLE V 3.5 Parts of a copolyether/ester of Example I and 1.5 parts of a copolyether/ester of Example III were dry-blended for a total of 33.4 percent soft segments and 5 extruded following the general procedure of Example IV, and using a final draw ratio of 7.5X with a draw temperature of 485°F and a take-up speed of 412 ft/min to obtain a size 2-0 monofilament suture. The physical properties of the resulting filaments are given in 10 Table II.

EXAMPLE VI The procedure of Example IV was repeated using various blends of copolyether/ester polymers of Examples I, II 15 and III having the compositions and blended in ratios as shown in Table III. The physical properties of the resulting filaments are also given in Table III.

EXAMPLE VII A copolyether/ester of Example I with 40 wt percent soft segments was dried and extruded in accordance with the general procedure of Example I using a 20 mil spinnerette to obtain a size 5-0 suture, and a 50 mil spinnerette to obtain a size 0 suture. Drawing conditions and physical 25 properties of the resulting suture are compared in Table IV with a size 2-0 suture of the same composition prepared according to Example I.

J! 'if riJJEtfy* 1 i SEP 1980 TABLE II Examples I II III IV V Suture size 2-0 o i cn o i cn o i cn 2-0 Diameter, mils (mm) 11.1 (0.28) 13.1 (0.33) 12.2 (0.31) 13.2 (0.34) 13. 2 (0.34) Knot strength, psi (Kg/cm2) 37,200 (2,600) 39,700 (2,780) 44,900 (3,140) 40,100 (2,800) 41,000 (2,870) Tensile strength, psi (Kg/cm2) 64,100 (4,490) 71,300 (4,990) 72 ,300 (5,060) 65,500 (4,580) 60,500 (4,200) Break elongation, % 31. 8 27.8 18. 3 .2 31.4 Visco-elastic elongation, % 18.6 13.3 7.25 .35 11.6 Yield elongation, % 3.2 2.9 2.6 4.2 4.7' Young's modulus, psi (Kg/cm2) 50,000 (3,500) 172,000 (12,000) 320,000 (22,400) 140,000 (9,800) 120,000 (8,400) >6 N) M t-3 />* r~ "VT! ""I-T3 r*- ■) Tf5!\? r'i TABLE III Polymer compositions Wt % soft Wt ratio segments of of components components Wt % soft segments in blend Young's modulus psi (Kg/cm ) Break elongation Eb, % Visco-elastic elongation Ev, % Yield elongation Ey, % 40/23 65/35 34.05 84,000 ( 5,850) 34.8 14.3 9.2 40/18 75/25 34 .50 107,000 ( 7,470) 33.4 13.3 3.2 40/23 50/50 31.50 105,000 ( 7,320) 33.7 14.7 1.9 40/18 70/30 33.40 120,000 ( 8,390) 31.4 11.6 4.7 40/18 65/35 32 . 30 134,000 ( 9,400) 27.5 12.1 4.6 40/18 60/40 31.20 140,000 ( 9,790) 26. 5 .2 4.8 40/18 55/45 .10 170,000 (11,920) 24.5 .8 2.6 40/18/23 /30/40 26.60 173,000 (12,080) 18.9 .3 3.5 40/23/18 /30/40 26 .10 201,000 (14,060) 22.4 .3 2.8 17 TABLE IV Suture size -0 2-0 0 Draw ratio '7.5 co • 00 7.3* Draw temperature, °F 340 530 370 Take-up, ft/min 205 485 110 Diameter, mils 7.08 11.10 14.03 Knot strength, psi (Kg/cm2) 48,600 (3,400) 37,200 (2,600) 34,200 (2,400) Tensile strength, psi (Kg/cm2) 67,500 (4,700) 64,100 (4,400) 68,600 (4,800) Break elongation, % 43.5 31.8 36.7 Visco-elastic elongation, % . 8 18. 6 17.6 Yield elongation, % 3.0 3.2 6.3 Young's modulus, psi (Kg/cm2) 49,000 (3,400) 50,000 (3,500) 51,000 (3,600) "•Two stage draw EXAMPLE VIII Monofilament sutures prepared from a copolyether/ester of Example II with 23 wt percent soft segments were sterilized by cobalt-60 irradiation and with ethylene oxide in accordance with conventional procedures for sterilizing surgical sutures. The physical properties of the sutures were affected only slightly by ethylene oxide sterilization, and even less by cobalt-60, as shown by the data in Table V. hi'H-4u7 1 921 38 18 TABLE V 1 921 3 Suture Nonsterile Sterilized control o 60 Co E.O.

Diameter, mils 12. 5 12.6 13.2 Knot strength, psi (Kg/cm2) ,300 (2,500) 33,400 (2,300) 29 ,900 (2,100) Tensile strength, psi (Kg/cm2) 70,300 . (4,900) 70,000 (4,900) 67 ,700 (4,800) Break elongation, % 28.2 31. 6 45.2 Visco-elastic elongation, % 13.2 . 0 23. 5 Yield elongation, % 2.9 2.3 2.2 Young's modulus, psi (Kg/cm2) 185,000 (13,000) 165,000 (11,600) 138,000 (9 ,600) The important physical properties of the sutures prepared from copolyether/esters are responsive to changes 15 in polymer composition and processing conditions. For example, visco-elastic elongation and yield elongation increase as the proportion of soft segments in polymer are increased, and conversely, Young's modulus decreases with an increasing proportion of soft segments. The 2-0 break elongation may be decreased and tensile strength increased by employing higher draw ratios during the manufacture of the suture. By regulation of the composition and processing variables therefor, it is possible to obtain specific mechanical properties for in-25 dividual sutures with a great degree of latitude.

While the preceding examples have been directed to the preparation of monofilament sutures of copolyether/esters, this was for the sake of convenience in describing one 3 0 polymer system and the effect of various polymer compositions and spinning conditions on fiber properties. The copolyether/ester polymers may also be used in the 1 921 38 19 manufacture of braided or other multifilament suture constructions, and single filaments and braids may be used in the preparation of surgical fabrics and knitted or woven prosthetic devices such as vein and arterial grafts.

In addition, elastomeric filaments having a combination of physical properties in accordance with the present invention may be prepared from other polymer systems such as polyurethane or silicone elastomers or polyether copolymers of urethane or silicone elastomers. Furthermore, 10 elastomeric filaments of the present invention may be blended with each other, with other elastomeric or non-elastomeric filaments, and with either absorbable or nonabsorbable filaments in order to provide yarns and fabrics with special properties, all of which is deemed to be in-15 eluded within the scope of the present invention.

L Q 'M7 0 L I JO

Claims

WHAT WE CLAIM IS:

1. An elastomeric surgical suture being a monofilament having the following combination of mechanical properties: Yield elongation - from 2 to 9 percent Visco-elastic elongation - from 10 to 30 percent Young's modulus - from 30,000 to 200,000 psi Tensile strength - at least 40,000 psi Knot strength - at least 30,000 psi

2. A suture of Claim 1 having a diameter of from 0.01 to 1.0 mm.

3. A suture of Claim 1 wherein the Young's modulus is 50,000 to 150,000.

4. A suture of Claim 1 wherein the tensile stress at the visco-elastic elongation yield point is less than one-third the suture tensile strength.

5. A suture of Claim 1 having an elongation to break of 30 to 10 0 percent.

6. A suture of Claim 5 wherein the elongation to break is at least 1.5 times the visco-elastic elongation.

7. A suture of Claim 1 wherein the visco-elastic elongation is at least 2.5 times the yield elongation.

8. A suture of Claim 1 in a sterile condition.

9. A suture of Claim 8 with a needle attached to at least e end thereof.

10. A suture of Claim 1 comprising a drawn and oriented monofilament of a segmented copolyether/ester polymer.

11. A drawn and oriented elastomeric surgical filament being a segmented copolyether/ester consisting essentially 2i 192 133 of a multiplicity of recurring long chain ether/ester units and short chain ester units joined head to tail through ester linkages and having the following general formula: 0 0 0 0 >1 II u II _ A(0 - D- O- C- R- C) (O-G-O-C-R-C - 0)v7 a. it n wherein G is a divalent radical remaining after the removal of terminal hydroxyl groups from a poly(C2_^Q alkylene oxide) glycol having a molecular weight of 350 to 6,000; R is a divalent radical remaining after removal of carboxyl groups from an aromatic dicarboxylic acid having a molecular weight less than 300; and D is a divalent radical remaining after removal of hydroxyl groups from an alkyldiol having a molecular weight less than 250; a and b are integers such that the short chain units represented by a comprise from 50 to 90 percent by weight of the composition; b is an integer such that the long chain copolymer segments represented by b comprise from 10 to 50 percent of the total copolymer composition; and n is the degree of polymerization resulting in a fiber-forming polymer, said drawn filaments being characterized by the following physical properties: Tensile strength - at least 40,000 psi Knot strength - at least 30,000 psi Yield elongation - from 2 to 9 percent Visco-elastic elongation - from 10 to 30 percent Young's modulus - from 30,000 to 200,000 psi

12. A filament of Claim 11 having a surgical needle attached to at least one end and useful as a surgical suture.

13. A filament of Claim 12 in a sterile condition. 22 192138

14. A filament of Claim 11 wherein G is derived from poly(tetramethyleneoxide)glycol, D is derived from 1,4-butanediol and R is derived from a phthalic acid.

15. A filament of Claim 14 wherein R is selected from the group consisting of terephthaloyl, isophthaloyl, orthophthaloyl, and mixtures thereof.

16. A filament of Claim 14 wherein said poly(tetramethyleneoxide) glycol has a molecular weight of about 1,000.

17. A filament of Claim 14 wherein the long chain units represented by b comprise about 4 0 wt percent of the copolyether/ ester.

18. A filament of Claim 17 comprising approximately 51 percent terephthaloyl units, 16 percent units derived from polytetramethylene ether glycol, and 33 percent units derived from 1,4-butanediol.

19. A filament of Claim 18 characterized by a visco-elastic elongation of about 19 percent and a Young's modulus of about 50,000 psi.

20. A filament of Claim 14 wherein the long chain units represented by b comprise about 2 3 wt percent of the copolyether/ ester.

21. A filament of Claim 20 comprising approximately 45 percent terephthaloyl units, 4 percent orthophthaloyl units, 2 0 percent units derived from polytetramethylene ether glycol and 31 percent units derived from 1,4-butanediol.

22. A filament of Claim 21 characterized by a visco-elastic elongation of about 13 percent and a Young's modulus of about 170,000 psi. — * "^rroFFfCS 23 t<jZ.I2>8

23.3. A filament of Claim 16 being a mixture of individual segmented copolyether/ester polymers having from 18 to 40 percent by weight long chain ester units wherein said filament contains an average of from 26 to 35 percent by weight long chain ester units.

24. A filament of Claim 2 3 wherein said polymer mixture comprises from 55 to 75 percent by weight of polymer having 40 percent by weight long chain ester units, and from 25 to 45 percent by weight of polymer having 18 percent by weight long chain ester units.

25. A filament of Claim 23 wherein said polymer mixture comprises approximately 30 percent by weight of a polymer having 40 percent by weight long chain ester units, from 30 to 4 0 percent by weight of a polymer having 2 3 percent by weight long chain ester units, and from 30 to 40 percent by weight of a polymer having 18 percent by weight long chain ester units.

26. A woven or knitted surgical fabric comprised of filaments of Claim 11.

27. A fabric of Claim 26 in a seamless tubular construction . WEST-WALKER, McCABE per: ATTORNEYS FOR THE APPLICANT