Laparoscopic suturing: effect of instrument handling on suture strength

In open surgery, handling of suture at any position other than the end is discouraged because of evidence that handling deforms and weakens the material. The limited operative field of laparoscopic surgery necessitates repeated instrument handling of suture, and the effect of such handling has not been investigated. We assessed the effect of trauma imposed on various suture materials by laparoscopic needle holders and forceps. Also, the ideal suturing technique (interrupted v continuous) according to the physical characteristics of the suture material and the optimal length for laparoscopic sutures were determined.

Sutures of 2-0 and 3-0 polyglactin 910 and 2-0 poliglecaprone 25 were tested. Controlled damage was inflicted by grasping the suture for 1 second between the jaws of either toothed laparoscopic grasping forceps or a laparoscopic needle holder at a pressure of 45 MPa. Blind physical testing was then performed using a computer-controlled tensile testing system. The length and proportion of suture extension prior to breaking and the tensile strength were measured. Samples of undamaged and controlled damaged specimens, before and after breakage, were examined by scanning electron microscopy (SEM).

The mean percentage extension in the control group was 46.3 mm for 3-0 Monocryl, 26.3 mm for 3-0 Vicryl, and 28.1 mm for 2-0 Vicryl. The mean tensile strengths were 47.9 N, 42.4 N, and 70.4 N for 3-0 Monocryl and 3-0 and 2-0 Vicryl, respectively. The 3-0 Monocryl and 3-0 Vicryl had significantly reduced tensile strength after damage compared with control sutures, whereas 3-0 Vicryl and 2-0 Vicryl had significantly impaired extension. After infliction of controlled damage with laparoscopic needle holders, the percent extension of damaged sutures was significantly less than that of undamaged sutures. Tensile strength was significantly lower for 3-0 Vicryl and 3-0 Monocryl after damage than before. The handling of Monocryl by laparoscopic needle holders and graspers produced punched-out defects and scratch marks, respectively. A number of damaged 2-0 and 3-0 Vicryl samples from the laparoscopic needle holder group showed disruption or unravelling of the braided filaments.

We expect that our results underestimate the potential effect on suture strength and extension inflicted by laparoscopic suturing. The exact length of suture material cannot be recommended from the findings. However, interrupted sutures should be preferred, particularly for long suture lines. In addition, the findings support the use of laparoscopic graspers in preference to needle holders. The combination of a grasper in one hand and needle holder in the other is ideal. Finally, urologists initially embarking on laparoscopic reconstruction must take meticulous care in their suturing technique and, in particular, the number of times and force with which the suture is grasped.