Good suture!

The devel­op­ment of sutures fol­lows the his­tor­ical trail of surgery. Its sev­eral-thou­sand-year-old his­tory is entwined with dif­ferent means and methods of wound closure.

Various pre­de­ces­sors of modern sutures devel­oped very early. The first indi­ca­tions of sur­gical suture methods were dis­cov­ered by researchers in 5,000-year-old Egyptian scrip­tures, which show, among others things, the illus­tra­tion of a suture needle with an eye. In addi­tion to plant fibers, another common suture mate­rial of the early period were ten­dons. Later, tex­tiles such as linen were used more and more often. Clear traces of tex­tile suture mate­rial were detected and ver­i­fied on a mummy dated 1000 B.C.

How­ever, wound infec­tions were often the result of using unclean, germ-laden instru­ments and mate­rials. This did not change until the Eng­lish sur­geon Joseph Baron Lister and his German col­league Curt Theodor Schim­mel­busch inde­pen­dently imple­mented the first usable dis­infection and ster­il­iza­tion pro­ce­dures at the end of the 19th cen­tury. From 1868 Lister used gut strings as suture mate­rial and dis­in­fected them with car­bolic acid – this marks the origin of the first catgut. Advan­tage of the mate­rial obtained from sheep or bovine intes­tine: It dis­solved grad­u­ally into the wound without leaving a residue and could be absorbed by the body. With the BSE crisis in the early 2000s, the use of catgut declined rapidly in favor of syn­thetic materials.

Modern suture materials

While sterility is a basic require­ment nowa­days, modern suture mate­rials have to meet com­pletely dif­ferent and mul­ti­fac­eted require­ments. In addi­tion to excel­lent gliding prop­er­ties of the thread when passing through the tissue to be oper­ated on, high tear resis­tance and knot secu­rity are among the cru­cial criteria.

As exten­sive as the require­ments for the thread are, the thread itself is just as varied. Syn­thetic or nat­ural mate­rials are twisted or braided into monofil­a­ment (single-fiber) or mul­ti­fil­a­ment (multi-fiber) thread vari­a­tions. Other options include sheathing or coating of resorbable or non-resorbable threads.

The designs and shapes of modern suture nee­dles are also extremely com­plex and ver­sa­tile. To make sure that tissue damage during surgery is kept to a min­imum, needle and thread are swaged. This means firmly con­nected, to keep the needle as thin as pos­sible, rather than pulling a large needle eye through the tissue. Every needle-thread-com­bi­na­tion has its own spe­cial fea­tures which the sur­geon, depending on wound and sur­gical tech­nique, has to take into account when making his choice.

Sophis­ti­cated pro­duc­tion process

There are some chal­lenges to over­come in man­u­fac­turing sur­gical suture mate­rial. After the needle-thread-con­nec­tion has been swaged, the needle is fas­tened in the so-called needle park of the thread car­rier, the tray. The thread is then wound on the tray with up to 800 rev­o­lu­tions per minute and ultra­son­i­cally welded with a paper lid. On the one hand the lid serves as a batch infor­ma­tion area and lists the spec­i­fi­ca­tions of the needle-thread-com­bi­na­tion. On the other hand, it serves as a drying agent in order to ensure a con­stant quality of the suture material.

During the winding process it is par­tic­u­larly impor­tant to con­trol the thread and to make sure that it does not end out­side the tray. Var­ious cam­eras help to comply with the high quality requirements.

Sterile pack­aging

When pack­aging sur­gical suture ma­terial, the trays are placed in the molded cavity of an alu­minum blister. The lid foil applied to it has a tear-resis­tant, punc­ture-proof and breath­able Tyvek window which enables ster­il­iza­tion by eth­ylene oxide gassing. During drying of the gassed blister, the mois­ture escapes through the Tyvek window, which is sub­se­quently removed. Finally, the blister con­taining the suture mate­rial is sealed com­pletely tight.

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Photos: Helmar Lünig