Class: BE210
Group: T4
Members:

Date: April 2004

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Abstract:  

  The use of sutures is one of the most common practices in the medical field and thus has direct effect on a great majority of the world's population.  In the US, over 250 million sutures are used each year.  From Syneture™ to Johnson & Johnson, many companies that manufacture sutures perform clinical studies to evaluate suture usefulness and attempt to validate claims that their sutures are the best.

The type of material that the suture is manufactured out of plays a large role in the effectiveness of the suture.  The ideal suture would be totally biologically inert and cause no tissue reaction. It would be very strong but simply dissolve in body fluids and lose strength at the same rate that the tissue gains strength. It would be easy for the surgeon to handle and knot reliably. It would neither cause nor promote complications. While great improvements in suture materials have been made in the recent past and modern sutures are very close to the above ideal, no single suture is ideal in all circumstances.

Different tissues have differing requirements for suture support, some needing only a few days (muscle, subcutaneous tissue, skin); whilst others require weeks or even months (fascia and tendon). Vascular prostheses require longer term, even permanent support.  The surgeon must be aware of the differences in the healing rates of various tissues when choosing a suture material. The surgeon wants to ensure that a suture will retain its strength until the tissue regains enough strength to prevent separation. Some tissues heal slowly and may never regain preoperative strength. Some may be placed under natural tension such as a tendon repair so the surgeon will want suture material that retains strength for a long time. In rapidly healing tissue, the surgeon may use a suture that will lose its tensile strength at about the same rate as the tissue gains strength and that will be absorbed by the tissue so that no foreign material remains in the wound. Excess tissue reaction to the suture encourages infection and slows healing. When taking all these factors into account, the surgeon has several choices of suture material available. Subjective preferences such as familiarity with the material and availability need also to be taken into account.

The other factor that ensures good results in dermatologic surgery is proper suturing technique. The postoperative appearance of a beautifully designed closure or flap can be compromised if an incorrect suture technique is chosen or if the execution is poor. Conversely, meticulous suturing technique cannot fully compensate for improper surgical technique. Poor incision placement with respect to relaxed skin-tension lines, excessive removal of tissue, or inadequate undermining may limit the surgeon's options in wound closure and suture placement. Below are a few examples of simple sutures used in the medical profession.  The "Running" stitch is made with one continuous length of suture material. This stitch is used to close tissue layers which require close approximation, such as the peritoneum. It may also be used in skin or blood vessels. The advantages of the running stitch are speed of execution and accommodation of edema during the wound healing process. However, there is a greater potential for mal-approximation of wound edges with the running stitch than with the interrupted stitch.

 In the Interrupted stitch, each stitch is tied separately. This stitch may be used in skin or underlying tissue layers. A more exact approximation of wound edges can be achieved with this technique than with the running stitch.  The Continuous locking/Blanket Stitch is a self-locking running stitch used primarily for approximating skin edges.  Although suture materials and aspects of the technique have changed substantially over time, the goals remain the same: closing dead space, supporting and strengthening wounds until healing increases their tensile strength, approximating skin edges for an aesthetically pleasing and functional result, and minimizing the risks of bleeding and infection. This experiment will attempt to provide some fundamental understanding of sutures by examining the effects of basic suture materials and suturing techniques.