A COMPARISON OF THE STRENGTH OF KNOTS TIED BY HAND AND AT LAPAROSCOPY

BACKGROUND: The strength of knots tied at laparoscopy was compared wit h that of hand-tied knots. STUDY DESIGN The force needed to undo or br eak eight types of knots that were tied in fresh postmortem human stom achs was measured. The knotting performance of nylon, polyglactin 910, braided silk, polytetrafluoroethylene, braided polyester fiber, braid ed polyester suture, poly amide 66, and polydiaxone was also compared. RESULTS: Measurements of knot strength of two to six half hitches (ha nd tied) showed that four half hitches were necessary to tie a secure nonslipping knot with most monofilament threads (nylon, polytetrafluor oethylene, braided polyester suture, and polyamide 66), while three ha lf hitches were adequate to secure a knot when polyglactin 910, braide d polyester fiber, silk, and polydiaxone were used. Additional throws did not increase knot strength once the knot no longer slipped (p=NS). Some commonly tied knots, three half hitches and surgical knots at la paroscopy were weaker than the same hand-tied knots (p<0.05) but an ad ditional throw increased knot security (p<0.01). Differences between l aparoscopic and hand-tied knot strengths were greater for monofilament than multifilament threads. There was a wider distribution of strengt hs for laparoscopically tied than hand-tied knots. Four half hitches w ere the most secure configuration for laparoscopically tied knots and were significantly stronger than three half hitches and surgical knots (p<0.01). The extracorporeally tied slipknot (Roeder loop) was signif icantly less secure than four half hitches (p<0.05). CONCLUSIONS: This study demonstrates that laparos copically formed knots may be weaker than those tied by hand and shows that improvements in knot strength a t laparoscopy can be achieved by choice of optimal knot configuration for different suture materials.