Mechanical analysis of the formation of forceps and scope for single-port laparoscopic surgery

The aim of this study is to demonstrate a shaft formation of forceps and scope which provides higher degree of freedom of motion for single-port laparoscopic surgery (SPLS). The key to smoothly performing SPLS lies in understanding the formation in which the shaft conflict is minimized. However, there have been no reported studies on conflict reduction in SPLS from a shaft formation perspective.

When performing SPLS, 3 instruments are passed into a narrow space, only 2 patterns of shaft formation can be obtained: a formation in which the 3 instruments rotate clockwise or counterclockwise (rotation formation) or a formation in which 1 instrument passes between the other 2 (cross formation). So motion spaces of the instruments in rotation formation compared with that in cross formation were tested using engineering methods. The range of the forceps' motion was assumed to be the space covered by the forceps till collision occurred between the moving forceps and either the other fixed forceps or the fixed scope. Examination of the range of movement of the scope was conducted in the same manner. The motion space with the area on the x-y horizontal is evaluated, as viewed from the peritoneal umbilicus port entry area.

The motion area of each instrument in rotation formation is 1.9 to 2.6 times wider than that in cross formation.

Rotation formation provides high degree of freedom of motion for SPLS.