Surgical manipulation and the tensile strength of polypropylene sutures.

Laboratory studies were performed on 509 size 6-0 polypropylene sutures to examine the effects of surgical manipulation on suture tensile strength. Results showed that dragging sutures over the torn edge of the foil package, permanently kinking sutures, or axially twisting them up to four times did not decrease tensile strength. Similarly, the tug exerted by operating room nurses on polypropylene sutures did not decrease their tensile strength. Two manipulations, however, did decrease breaking strength. The presence of a stray knot reduced suture strength 17%, and grasping sutures with DeBakey forceps decreased suture strength in a dose-dependent fashion. When experienced surgeons grasped sutures with forceps out of direct vision, their grasping forces were well below that which alters tensile strength. Nevertheless, these results demonstrate that sutures that have acquired a stray knot should be discarded and that sutures should not be grasped with mechanical devices such as forceps.