Patented Apr. 30, 1935 1999,641 UNITED STATES PATENT OFFICE 1999,64. STRAND FOR, SUTURE AND OTHER PUR POSES AND METHOD OF MAKING THE "SAVE George Aaron Sharp, Los Angeles, Calif., assignor to Davis & Sharp, a corporation of California. No Drawing. Application July 30, 1932, Serial No. 62,25. Renewed October 26, 1934 22 Claims. (C. 128-335,5) This invention relates to sutures, ligatures, tory to employ long coarse tendon fibers, Such as cords and the like, and to methods of manufac those obtained from the tendon fascia, lata, turing the same. derived from the thighs or quarters of steers or It has been common practice to make sutures, beeves. It has been attempted heretofore to 9 Such as are Ordinarily used in surgical work, of make sutures from such tendons, but as far aS Catgut, which is most frequently produced from I am aware, they have never been produced Com sheep intestines. mercially, for a number of good rea,Sons. Such catgut sutures are relatively expensive, It is difficult to obtain twisted Strings or cords because of the expert and laborious hand work from Such tendon material by approved textile 0. required in their manufacture and because of the processes and machinery, and it has been pro O relatively high prices of the sheep intestines posed, but without success, to utilize relatively caused by great demand for other purposes. In less satisfactory braided cords or Strings, the con addition, catgut, while extensively used because stituent fibers of which are caused to adhere to of the absence of something better, is not entire gether by glue or other adhesive; or to form the ly Satisfactory, due to the difficulty of obtaining material into thin sheets, by Overlapping and 5 catgut Sutures of uniform size, of sufficient pressure, which sheets were to be slit into rib Strength and flexibility to permit most efficiently bons. Sutures prepared of a plurality of braided of the Stitching and tying necessitated in surgical fibers glued together have been Suggested for Work, and because of the difficulty of rendering surgical work, but did not prove satisfactory be 20 then sterile and capable of being treated at ade cause they do not remain homogeneous in the 20 site Sterilizing temperatures without deteriora tissues. The lytic substance such as the lymph O in the tissues will dissolve the adhesive, with the Intestinal tissues, forming the basis of catgut, result that within a relatively short time the con are porous and are almost always infected and stituent fibers will fall apart, permitting the Su 2 5 contaminated with harmful pathogenic bacteria, tures to disintegrate. 25 particularly of tetanus or lockjaw variety, and in Among the particular objects of the present many cases of the anthrax type. These bacteria invention are, therefore, to prepare substan withstand relatively high sterilizing tempera tially pure collagen Sutures from the fibers of tures. Sheep catgut also usually contains fats, animal tendons, which may be readily spun or 30 mucosa, irritating fatty acids and other impuri twisted into a cord, strand, Suture or ligature 30 ties, which are not altogether eliminated by the by approved textile processes, and which may be many purifying and scraping operations to which formed into a homogeneous and unitary cord , the catgut is subjected. These last-mentioned or string without an added adhesive and of such inpurities cause the catgut to become harsh and structure as to withstand the action of tissue brittle, and to decrease in strength and flexibility, solvents and sterilizing temperatures without any 35 particularly when it is subjected to sterilizing substantial disintegration or impairment. temperatures. In One embodiment of my invention, the pure Among the objects of the present invention are White connective tissues contained in the leg to provide sutures which will be free from these tendons of year-old veal, or calves, or of sheep, 4) defects, which may be easily and readily manu and preferably the tendo Achillis derived from 40 factured from inexpensive raw materials, and by the hind legs of Such calves or veals are utilized, automatic machinery of the type usually em as preferred tendon materials. ployed in the textile industries; which will be AS a Specific example of one method of pre normally, sterile or which may be readily sterilized paring the Sutures of the present invention, the at high temperatures without substantial deteri following is given: The muscular, fatty and other 45 oration, which will have sufficient strength and tissues adhering to these tendons are removed, flexibility to be efficiently and facilely stitched and the tendons are then dried. These tendons and tied in Surgical operations, even after treat are usually about 2 to 2% inches long, and as ment or effective sterilizing temperatures, and slender as perhaps One-eighth of an inch, With 50 Which may be made of controlled and uniform about 300 of them producing one pound of fiber, 50 Sizes for any desired purpose. 30,000 tendons being approximately equivalent In accomplishing these objects it has been to a one hundred pound run of fiber. found satisfactory to employ animal tendons. In After drying the tendons, they are run through preparing sutures from animal tendons experi a machine, which will crack off the capsule or 55 ments have demonstrated that it is not satisfac tendon sheath, and also open up the interior fiber 55 2 1999,641. structure so that the shredder teeth can get in sutures. Sutures are customarily cut into 5 foot between them and tear the fibers apart. lengths and put into glass tubes, the surgeons The shredder, which is next emplgoyed, will later cutting them into shorter lengths as re Separate the fibers so as to prepare them for quired. The cord is also wound on the drums so carding. In the carding machine the material is that no two laps of the cord will touch one an 5 carded and combed down to very fine fibers and other, which permits of perfect processing and thereafter is passed into a roving machine, which prevents adhesion between the different laps of forms the fibers into a very small roving, so cord. The drum with the cord wound upon it delicate that it is just able to hold together. now is put into a substantially constructed vac O These rovings are passed into a spinning ma uum chamber, and there every vestige of moisture 0 chine, from which they are obtained in the form is extracted under high vacuum and at a tempera of fine yarn, and this yarn is passed into a twist ture of about 52 C., for a period of about 75 ing machine which takes several strands of minutes. the yarn and twists them into what is, after At the completion of the seventy-five minute 5 further treatment, to become the final substan drying period, a caustic solution, preferably of tially transparent or glossy cord of very attrac the same temperature as the inside of the vac tive appearance and external smoothness. uum chamber, is passed into the vacuum cham These spun cords or strands thus formed are ber to Submerge the drum. With the cord there then treated with carbon tetrachloride or with upon. A Satisfactory caustic or alkaline Solution 20 Some other Suitable fat solvent in a Soxhlette for this purpose may consist of a 0.235% sodium 20 apparatus. The fibers are also subjected to the carbonate solution in distilled water. Selective digestive action of enzymes, such as After addition of the caustic solution the same lipase and trypsin which will dissolve out or re high vacuum is reestablished, but the tempera move the other impurities from the animal ma ture is gradually allowed to decline to 45° C., and 25 terials namely, the mucin and elastin with the this temperature is maintained for eighteen 2 5 ultimate object of producing fibers of pure col hours. lagen. The Selective enzymes are present in an After eighteen hours the drum with the strand alkaline bath or baths and have a selective diges thereoni is removed from the vacuum chamber tive action on the fat, mucin and elastin present and for several hours is subjected to a Washing 30 in the fibers, but do not have any digestive ac operation in running distilled water. The drum 30 tion on the collagen. The cords or strands or and strand next is placed in a bath of hydro their fibers are allowed to remain in the bath chloric acid solution for neutralizing the caustic, or baths for a sufficient time to properly digest and then it is placed in a weak solution of Sodium the impurities mentioned. By removing the non carbonate to neutralize' any acid. Then it is 35 essential impurities, namely, the elastin, mucin again washed in running water, and this time and fats, which is accomplished by the selective for about twelve hours. digestive enzyme step or steps of the method, After this washing operation the drum of cord the bulk or size of the cord or strand is reduced is air dried for about twenty-four hours in a and elasticity properties are greatly improved. normal atmosphere, and after that is dried in a 40 To neutralize any fatty acids which may be pres vacuum chamber under a relatively high vacuum 40 ent in the fibers at this stage, a neutralizing at 52 C. agent, or an alkali, such as sodium carbonate, The thoroughly dried cord is then subjected may be employed. After these solvent treatments, to a treatment of formalin to coagulate or harden the cords or strands are washed in distilled it and to render it more slowly absorbed in the 45 running water for about three hours to remove tissues for definitely predetermined lengths of from their fibers all traces of the treating chem time, such as 10 days, 20 days, 30 days, etc., as icals and other objectionable substances. Then variously required by Surgeons. they are dried in a vacuum chamber at a tem Finally after the formalin treatment, it is put perature gradually increasing to 65° C. through a surface treatment machine which gives 50 The cord thus prepared is then treated to unite it a smooth highly polished surface, whereupon 50 to each other the adjacent surfaces of the con it is ready to be cut into proper lengths, put into . stituent separated fibers or materials, as by a glass tubes and sterilized. This surface treat Suitable combination of chemical acid and/or ment may include the application of a coagulable alkaline baths, with the result that a homo coating applied to the strand. If applied, this coating should be of a character that is insoluble 5 5 geneous or unitary strand or cord of fibrous ma in water. In practice, I have found that a strand terial of substantially pure collagen tissue is ob coated with coagulated albumen will properly re tained. The chemical utilized in this fiber-sur sist absorption when in the tissues. That is to face union treatment may be selected so as not say, a coating of the kind stated is slowly digesti 60 to cause substantial deterioration of the collagen ble by the enzymes of the body tissues, is non 60 base, and should be of such a nature that it will irritating when the coated Strand is used as a not have any disadvantageous effect in subse suture, and is in Soluble in Water. Blood albumen, quent surgical utilization. In any case, the chem which may be coagulated by heat or a chemical ical substance/should be removed as far as pos coagulant, has been found to be especially adapted 65 sible from the resultant homogeneous cord or for the purpose although others may be employed. ligature material. The above example describes a very complete One method of forming the unitary Strand or process, and it is to be understood that some of homogeneous cord which may be employed under the steps thereof may be omitted or modified suitable circumstances is as follows:- to produce a cord or suture of satisfactory prop 70 The cord, after the twisting operation, and the erty. Also many other fiber uniting and homo treatment described, is wound on a drum or reel genizing steps or processes may be employed, in with spokes about 60 inches apart, so that it will volving either physical or chemical treatments, be substantially free and without contact with or both. the drum or reel throughout the length into which The resultant surface united or homogenized 75 it is to be cut for putting up into tubes as Surgical fibers constitute a Substantially unitary cord, 1,999,641. 3 thread, suture or ligature formed of highly pure present invention achieves this same desirable collagen. Although it still retains its longitudinal result without necessitating the utilization of or grained structure, the individual fibrous char strips of living fascia. For this reason sutures of acter has been eliminated only to the extent that the present invention are of particular and out the fibers are surface united by their own inherent standing value in operations for hernia as well 5 adhesive properties, and the many individual as for various abdominal and other operations. Small fibers of which the strand is composed are Furthermore, the Suture material prepared in no longer free as such, The homogeneity of the accordance with the processes of the present in cord or fiber formed is particularly advantageous vention, may be cut or separated into sections to 0. in the case of sutures in Surgical Work as it is provide elements of desired length, and it will be unaffected by the lytic substances such as the obvious that by this method the fibers may be lymph in the tissues and will not disintegrate formed into a continuous uniform strand, and into the constituent fibers, though it remains in which in turn may be cut into predetermined. the tissues for relatively long periods of time. lengths, whereby sutures of uniform thickness Sutures made in accordance with my invention and length may be obtained. have been used extensively in animal experimen Another advantage incident to the manufac tation and also in the human body, and it has ture of the suture of the present invention in CCn proven beyond doubt that they do withstand tinuous lengths resides in the fact that the permeation by the body fluids and retain their strands may be wound upon large spools, as in strength fully as long if not longer than the best the manufacture of cotton, flax, hemp and jute grades of catgut made from sheep's intestines, cord. Such continuous lengths render it possible and furthermore they are superior to catgut in to employ machines for winding sutures into Small many fundamental ways as herein described. loops for insertion into glass tubes. This is work Moreover, and of prime importance in the case that is now necessarily done entirely by hand be 25 of Sutures, the resulting strings or cords will en cause of the fact that catgut strands cannot be 2 dure sufficiently high sterilizing temperatures to made in continuous lengths, and cannot there kill all micro-organisms including the highly re fore be fed into automatic machines to Wind then Sistant spores of tetanus and anthrax. Patho into Small loops to be inserted in glass tubes. genic micro-organisms, and especially the Spores Although the suture or ligature material of the O of tetanus and anthrax, are not always killed at present invention is particularly advantageous 30 the temperature generally used for sterilizing cat in surgical work, cords, strings and the like pre gut sutures, which is dry heat at 275 degrees F., pared in accordance with the present invention whereas catgut cannot stand a higher tempera may also be used for a variety of other purposes, ture than 275 degrees F. Without severe deteriora such as the stringing of tennis rackets, musical 5 tion. This, obviously, is not a sufficient margin instruments and other articles or devices. of safety. Indeed, the fact that it is not a suffi In the practice of my invention, the strands cient margin of safety has been evidenced in two or cords may be made of various thicknesses and ways: by bacteriological tests, and by the inci strength to be utilized for such purposes, and dence of infected wounds, following surgical op where for example the strand is intended to be 40 erations, where the source of the infections has utilized as a string for a musical instrument, this been traced to the catgut Sutures used, and which uniformity of size is a distinct advantage in giv sutures were sterilized in the manner described. ing more perfect tonal effects, because of the The suture material of the present invention uniform diameter of the string, as opposed to withstands a sterilizing temperature in excess of the inaccurately hand-made catgut strings, 330 degrees F., without impairment, thus afford which latter are unavoidably of uneven or vary ing a margin of safety of fully 55 degrees F. This ing diameters. On the other hand, in the string is a tremendous advantage, as it eliminates One ing of tennis rackets, the greater the strength of the most serious hazards which still beset and the better the resistance to moisture, cou surgery, and enables the prevention of countless pled with greater economy, makes them far more cases of post-operative infections and many desirable for such purpose than the expensive deaths. In addition, the Suture of the present catgut strings now employed. invention is more flexible and of greater strength While I have herein shown and described one after sterilization than catgut, and this facili particular embodiment of my invention, it is to tates the surgeon's work and brings about a be understood that I do not confine myself to all 5 5 shorter operation time, the latter a feature of im the precise details of the construction herein set 5 5 portance from every viewpoint, especially in cur forth by way of illustration, as modifications and tailing the periods of anesthesia, and of Surgical variations may be made without departing from shock. the spirit of the invention, or exceeding the scope Another advantage which the suture of the of the appended claims. 60 present invention has over catgut is that when What is claimed is: 60 suture material becomes absorbed, the tract or 1. A strand for use as a suture and for other hole which it makes through the tissues becomes purposes, composed of substantially pure collagen grown full of scar tissue, thereby providing ad fibers, the contacting surfaces of which are inti ditional strength for the continued support or mately united into an homogeneous structure by holding together of the tissues even after the their own inherent adhesive properties, said wounds have healed. On the other hand, with strand having a smooth outer surface. catgut the tracts or holes become filled with mere 2. A strand for use as a suture and for other ly the muscle, the fascia or other tissue Surround purposes, composed of substantially pure collagen ing it. The advantage of providing Scar tissue fibers derived from the leg tendons of young ani (beneath surface, not on the skin) is of great im mals, said fibers being formed into a roving and -portance in surgery, and to obtain this advan spun into a strand and the contacting Surfaces tage surgeons sometimes use strips of living of which are intimately united into an honoge fascia, lata, so that strong supporting ligaments neous structure by the inherent adhesive prop or bands of scar tissue are formed, to give addi erties only of the fibers. 5 tional support to the wound. The suture of the 3. A strand for use as a suture and for other 75 4. 1999,641. purposes, composed of Substantially pure collagen 13. The hereindescribed method of producing fibers, the contacting surfaces of which are inti sutures and similar cord-like structures, which mately united into an homogeneous structure by comprises treating animal tendons to separate the inherent adhesive properties of the fibers, said the fibers from the flesh, mechanically segregating Strand having a coating of a Water insoluble Sub the fibers into single fibers, purifying the fibers stance. to remove the fats, mucin and elastin to convert 4. A strand for use as a suture and for other them into Substantially pure collagen, forming purposes, composed of substantially pure collagen the fibers into a roving, spinning the roving into fibers spun into a strand, said fibers being inti a single strand and then softening the strand to 0 mately united into an homogeneous structure by surface-unite and homogeneize the fibers by their 10 their own inherent adhesive properties, and the own inherent adhesive properties to form a uni Strand having a coagulated coating of a water tary Strand. in Soluble substance. 14. The hereindescribed method of producing 5. A strand for use as a suture and for other sutures and similar cord-like structures, which 5 purposes, formed from a plurality of intertwisted comprises treating animal tendons to separate 15 Spun strands composed of substantially pure the fibers from the flesh, mechanically segregat ... collagen fibers derived from the leg tendons of ing the fibers into single fibers, forming the fibers young animals, the fibers of the separate strands into rovings, twisting the rovings into a single being surface-united into an homogeneous struc strand, treating the Strand with tissue digestives 20 ture by their own inherent adhesive properties. to remove the impurities including the fats, 20 6. A strand for use as a suture and for other mucin and elastin and without affecting the purposes, formed from a plurality of intertwisted collagen, and then chemically softening the Spun Strands of pure collagen fibers derived from strand to homogeneize and surface-unite the the tendons of young animals, the said fabers be fibers into a unitary strand by the inherent ad 25 ing Surface-united into an homogeneous struc hesive properties of the fibers. 25 ture by their own inherent adhesive properties, 5. The hereindescribed method which consists and the said strand having a suitable albumen in Selecting animal tendons derived from the pure coating to render it smooth. white connective tissues of the class defined in 7. A strand for use as a Suture and for other the tendo 'Achillis' of young animals, combing 30 purposes, formed from substantially pure collagen the tendons into a fibrous mass, mechanically 30 fibers. derived from the pure white connective Segregating the mass into Single fibers, forming tissues in the leg tendons of veal, calves, and the fibers into rovings, spinning and twisting sheep, said fibers being carded, formed into a the rovings into a single strand, purifying the roving and spun into a strand and intimately fibers to remove all impurities and thus reduce 35 united into an homogeneous structure by the in them to substantially pure collagen, then chemi 35 herent adhesive properties of the fibers. cally softening said strand with an acid and an 8. A Strand for use as a suture and for other alkali to surface-unite and homogeneize the purposes, formed from substantially pure collagen fibers by their own inherent adhesive properties, fibers derived from the tendo “Achillis' of veal and then drying the strand. 0 and calves, said fibers being formed into a rov 16. The hereindescribed process, which com 40 ing and spun into a strand and the contacting prises Selecting the leg tendons of young ani surfaces of which are united into an homogeneous mals, drying the tendons and reducing them to structure by the inherent adhesive properties only fiber form, carding the fibers and forming them in the fibers. into small rovings, spinning the rovings into fine 9. Astrand for use as a suture and for other strands, twisting several strands to form a cord, purposes, formed from substantially pure collagen Subjecting the cord to the action of Selective tissue fibers derived from the tendons of young animals, digestive enzymes to purify it by removing the and comprising a relatively large number of said fats, mucin and elastin and thus convert the fiberS Spun and twisted together and surface fibers into substantially pure collagen, and then united into an homogeneous structure by their chemically softening the fibers to Surface-unite Own inherent adhesive properties. and homogeneize then by their inherent adhesive 10. A strand for use as a suture and for other properties, then drying the cord to form a unitary purposes, formed from substantially pure collagen and homogeneous structure. fibers derived from the smaller tendons of ani 17. A spun strand for use as a Suture and for 5 5 mals, the contacting surfaces of the fibers being other purposes, composed of substantially pure intimately united into an homogeneous structure collagen fibers derived from the tendons of ani by their own inherent adhesive properties ren mals, said strand being purified by treatment dered adhesive by the softening action of chemi with selective tissue digestive enzymes to remove cals. the fats, mucin and elastin, and the fibers being 60 11. A strand for use as a suture and for other 60 purposes, formed from substantially pure collager surface-unitedproperties. by their own inherent adhesive fibers derived from animal tendons, said fibers being purified by treatment with fat solvents and 18. A surgical suture composed of animal ten tissue-digestives, the contacting surfaces of the don fibers derived from the leg tendons of young 65 fibers being intimately united into an homo animals, said fibers being treated with selective geneous structure by their own inherent adhesive tissue digestive enzymes to remove the unde properties. - sirable impurities such as fats, mucin and elastin, 12. A strand for use as a suture and for other and spun into a strand, said fibers being surface purposes, composed of Substantially pure collagen united by their own inherent adhesive properties 0. fibers derived from the Smaller tendons of ani and the strand having a lymph-resistant coating. 70 mals, the contacting surfaces of the fibers being 19. A surgical suture consisting of a spun strand intimately united into an homogeneous structure composed of Substantially pure collagen fibers by their own inherent adhesive properties, and derived from the leg tendons of young animals, said strand having an homogeneized and polished the surfaces of which are intimately united into 5 surface. an homogeneous structure by their own inherent 1999,641 5 adhesive properties, and said strand having a 22. The method of surface-uniting and homo , coagulated coating consisting of a substance re geneizing the constituents of a cord composed of sistant to body fluids. spun collagen fibers derived from animal tendons, 20. A strand for sutures and other purposes, which consists in winding the cord upon supports, composed of spun animal tendon fibers surface removing moisture therefrom, submerging the united and homogeneized by their inherent ad Supported cord in a caustic Solution, Washing and hesive properties and having a moisture-resistant then drying the cord and finally subjecting the coating. . . . supported cord to an acid treatment to soften and is 21. A strand for suture and other purposes com thus surface-unite the individual fibers into an posed of spun animal tendon fibers derived from homogeneous structure by thie inherent adhesive 10 i 10. the tendons of young animals, said fibers being properties only of the fibers. homogeneized and having a coating of a lymph resistant substance capable of digestion by the GEORGE AARON SHARP, enzymes of the body tissues.