Impact of fenestrations and surface profiling on the holding of tissue by parallel occlusion laparoscopic graspers.

BACKGROUND: Despite the importance of efficient grasping during laparoscopic surgery, the published literature on jaw features, e.g., fenestrations and surface profiling on grasping efficiency defined as resistance to slip without inflicting trauma, is limited. METHODS: Various surface geometries of the jaws were tested with respect to (i) inclusion of fenestrations; (ii) surface contact to fenestration area ratio, and (iii) surface profiling of the jaws. Various loads were applied to the tissue which was subsequently pulled at a constant rate until free from the jaws. The maximal force necessary to pull the tissue free was recorded. The jaws were designed for use in parallel-occlusion graspers to avoid the well documented high pinch forces encountered with pivoted occlusion. RESULTS: At all applied forces the force needed to pull tissue from any fenestration design was significantly higher than the force necessary to pull tissue from non-fenestrated jaws (p < 0.05) with no significant differences between the three fenestration designs. The ratio of surface contact to fenestration area must exceed 1:0.4 to achieve a significant increase in the tissue retention. All the profiles studied were made using a single fenestration and with a surface contact to fenestration area ratio of 1:0.8. All such profile designs studied performed significantly better than the control (p < 0.005). The ratio of the mean retraction to applied force across all load conditions tested were 1.23:1.0 and 1.7:1.0 for the waved and toothed profile respectively, with standard deviations for the corresponding retraction force of ±0.45 and ±0.38 respectively. CONCLUSIONS: The retention efficiency of laparoscopic graspers is improved by fenestration which must, however, exceed a certain ratio (>1.0:0.4). Likewise surface profiling of the jaws enhances retention efficiency and its design (tooth, waved, mixed) directly influences the amount of pressure needed to retain tissue.