In no part of surgical technique is sterility of so great importance as in the preparation of ligatures and sutures. They are implanted in wounded tissues, and any germs which they may contain are placed in the most favorable conditions for growth, being harbored in a foreign body (the ligature), and supplied with abundant nutriment in the form of extravasated blood and damaged tissue cells. Any material for ligatures or sutures, therefore, which cannot be sterilized with certainty should be thrown out of the surgical armamentarium. A number of surgeons have at one time or another decided that catgut fell under this ban, and have refused to employ it under any circumstances. It is now pretty generally admitted, however, that it can be sterilized by a number of methods with sufficient certainty to warrant its general employment.Sutures and ligatures are primarily divided into those which are capable of disintegration within the tissues, and those which remain unchanged either permanently or for a very long period of time. The names absorbable and non-absorbable are applied to these two classes. All the non-absorbable materials can be sterilized by boiling in water or in a steam sterilizer.
Various animal tendons, strips of hide, and nerves have been employed as sutures and ligatures, but they have been almost entirely supplanted by catgut. It is cheap, it can always be obtained in any size, and in strands of sufficient length, and if properly prepared, it has great strength. Moreover, it is quickly disintegrated in the tissues, the ordinary sizes being wholly taken up in the course of a week or two, so that no foreign body remains in the wound indefinitely. Its one disadvantage is the fact that it cannot be sterilized by steam or boiling water, for in both of these it cooks to a jelly in a few minutes.Sterilization of Catgut – It can be boiled in alcohol in a water bath or sand bath, but as alcohol boils at 174° F, the temperature is not sufficient to kill all germs. This method is therefore unreliable.Catgut may be sterilized by dry heat. Boeckmann’s method is as follows: The catgut is soaked in ether one week to remove the fat. Single strands are then wound in rings, and each wrapped in paraffin paper and sealed in a paper envelope. The envelopes are placed in a dry sterilizer and heated to 300° F for three hours on two successive days.Catgut may be sterilized by chemicals. Claudius’s method is the simplest. Commercial catgut without any preparation is wound in single layers on glass spools and dropped into a jar containing one part of iodine and one part of potassium iodid to one hundred parts of distilled water. The jar is tightly covered and allowed to stand for one week. For use the spool containing the catgut is removed and immersed in sterile water, in order to free the catgut from the excess of iodin. Spools which have been partially used can be resterilized until the catgut becomes brittle, which it is apt to do if it remains for more than three months in the above mentioned solution. After one week’s immersion in the iodin solution, the spools may be removed and kept in alcohol. This is the simplest reliable method for sterilizing catgut in the office.Catgut may be so treated with chemicals that it can be boiled in water. This result may be obtained by soaking the catgut in a solution of formaldehyde, but during the entire process the catgut must remain tightly stretched upon glass plates or large spools. A simpler method is that of Elsberg. The raw gut is freed from fat by immersion in ether or chloroform, or a mixture of one part chloroform and two parts ether. It is then wound tightly in a single layer on large glass spools, having a hole in each flange in which the ends of the gut can be tied. The spools are boiled for ten minutes in a saturated solution of ammonium sulphate with one per cent of carbolic acid. The spools are then removed with sterile forceps, rinsed for half a minute in warm sterile water, and placed placed in strong alcohol. Partially used spools can be resterilized, and the solution of ammonium sulphate in which they are boiled can be used indefinitely by the addition of water to take the place of that which has evaporated.Catgut may be sterilized by boiling in some substance which has a higher boiling point than water, and which at the same time will not so alter the catgut as to render it weak or brittle. One of the best substances for the purpose is cumol, which boils at about 330° F. The method is a little too complicated for office use.Catgut may be sterilized by immersion in alcohol heated under pressure in order to obtain a high degree of temperature. This requires special apparatus, and is not a method suitable for general office use.Catgut sold in sealed glass tubes is usually prepared by one of the two methods last mentioned. Catgut prepared in this manner costs from ten to twenty-five cents a piece.Commercial catgut comes in coils of one hundred feet, costing in the sizes usually employed from fifty cents to one dollar a coil.
As stated above, plain catgut disintegrates in the tissues within a few days. Under certain circumstances this is a disadvantage – for example, in suturing the various fascial planes in order to cure a hernia, it is desirable that the sutures shall not give way until the granulation tissue becomes firm. For such purposes, catgut is prepared to resist disintegration by soaking it in potassium bichromate or chromic acid for twenty-four to forty-eight hours. A good method for office use is that of Elsberg, mentioned above, with the addition of one part of chromic acid to one thousand parts of the ammonium sulphate solution.The longer the catgut remains in the solution of chromic acid or bichromate of potash, the harder it becomes, and the longer will it resist disintegration in the body. Chromic catgut or chromatized catgut is sold as “ten day catgut,” “twenty day catgut,” etc. These figures are not very reliable estimates, and should not be too implicitly depended upon. If the catgut remains too long in the hardening solution, it will become practically indestructible in the tissues of the body. Buried sutures of such material have often been removed months afterward without their showing the slightest change.
Kangaroo tendon was formerly employed a great deal for the deep sutures in hernia operations. The tail tendon of the kangaroo naturally splits into round cords which make excellent sutures. The fibers in the leg tendons have to be pulled apart mechanically, like the fibers in the tendons of the domestic animals. This gives a rough thread of uncertain strength. many of the kangaroo tendons sold at the present time have very little value. Chromic catgut is gradually taking its place.
Twisted or braided silk is by far the commonest material employed for sutures. Some surgeons also employ it for ligatures on account of their fear of infection from imperfectly sterilized catgut. Black silk is preferable to white for most sutures, as the stitches are more readily seen and removed. Silk possesses the very great advantage of being easily boiled in water at the time of the operation. Any good black sewing silk answers the purpose satisfactorily, although many surgeons prefer to buy specially prepared and sterilized silk sutures in sealed glass tubes, costing from fifteen to twenty-five cents each.For tying large pedicles, floss silk is often employed. This is a loosely twisted, very flexible, and strong thread, and answers the purpose remarkably well. The practice of mass ligation, however, is falling into disuse, as it is now generally recognized that the blood-vessels should be ligated separately, and the wounds in the other tissues should be closed by suture with finer thread.
This material, which is familiar to every fisherman, is obtained from the silkworm just before he spins his cocoon. It is at the time in a viscid state, and is pulled out into a long string and allowed to dry. This gives a hard, elastic smooth thread, almost like wire. These threads can be obtained in bundles of one hundred of dealers in fishing tackle. Such bundles cost from forty cents upward, according to the size and length of the individual threads. They can be sterilized by boiling in water or by steam; or they can be obtained in sealed glass tubes, costing from fifteen to twenty=five cents each. Silkworm gut is even less irritating in the tissues than silk, and is an excellent material to employ when deep sutures are required.
Black or brown hairs from the tail of a horse make excellent sutures for skin wounds. They should be washed with soap and water, and then with alcohol. When needed they are easily sterilized in boiling water or in steam. They are not as strong as silk, but they are able to resist all the tension which any suture ought to have. They can also be obtained ready sterilized, six in a tube, at twenty cents; or dry in bottles or envelopes at a considerably cheaper rate.
Although silk is generally used in preference to other manufactured threads, this is largely a matter of custom. cotton or linen thread is easily sterilized by boiling, does not irritate the skin, and forms a perfectly satisfactory suturing material. No one need hesitate to use either in an emergency, nor, for that matter, in his regular practice. If a colored thread is used, it should have a fast dye, or else it should be boiled long enough to extract so much of the dye as is easily soluble.
Thread dipped in celluloid is often employed in operations upon the stomach and intestine on account of its impervious character. It is prepared in the following manner: A gray linen thread is boiled in one per cent solution of carbonate of sodium, wrapped in sterile gauze, dried in hot air, and then dipped in a solution of celluloid which is heated in a hot air sterilizer. I is dried and then placed in a sterile receptacle until wanted.
Pure silver wire is used for suturing bones, and also by some operators for sutures of the cervix, perineum, harelip, etc. The sizes usually employed are Nos. 24 or 30. Such wire costs about two dollars and fifty cents an ounce. It is also used in the manufacture of filigrees, employed in some operations for hernia. Other kinds of wire, and notably an aluminum bronze, are employed a good deal in Germany, but have never obtained much popularity in this country. Antiseptic powers are claimed for them by their advocates.