The surgeon's preference usually determines which suture knot he want to use in conventional surgery. The choice may be somewhat restricted in laparoscopic surgery because access to the target tissue and techniques for suturing and tying the knot may be limited. For extracorporeal knots (slip or square knots), a suture material that slides easily (such as silk, catgut, or a monofilament suture ) is preferable. In suture material that slides easily, however, the first hitch may loosen before the second hitch can be secured. Thus, in some cases a material that does not slide as easily but that provides a good knot strength will be preferable. Although sutures made of polyglycolic or polyglactic acid may be used as in conventional surgery, it may be difficult to slide the knot in place smoothly using these materials. Tayside knot is a good extracorporeal knot for a suture material like silk.