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Geometry of laparoscopic suturing and knotting techniques.

BACKGROUND
Spatial limitation, together with a fixed trocar position, restricted handling, and movement of the instruments, is inevitably associated with reconstructive laparoscopy and retroperitoneoscopy. This problem includes not only suturing technique and instruments but also geometric factors of endoscopic reconstruction, such as optimal distances between the working trocars, length of instruments, and angles between the instruments and the object. We present an experimental access to determine the specific impact of these factors on reconstructive laparoscopy.


MATERIALS AND METHODS
In an in vitro model, end-to-end anastomoses of porcine intestine were performed using a standardized intracorporeal suturing technique. Suturing was performed without and after training in reconstructive surgery with variation of the following geometric factors: (1) the distance between the working trocars (between 6 and 12 cm); (2) the position of the object (lateral right, medially, lateral left); (3) the camera position (medially, lateral right, lateral left); (4) the angle between the instruments and a horizontal line (15 degrees , 55 degrees, 90 degrees); (5) the intracorporeal length of instruments (between 10 and 25 cm); and (6) narrowed space available for the instruments (between 4 and 25 cm).


RESULTS
Continual training decreased the time required for suturing between 30% to 50%. Training decreased the time required for nonsuturing activities between 50% and 70% but the time required for suturing activities only between 20% and 45%. If the space between instruments and camera was limited, shifting the camera into a lateral position simplified the procedure of intracorporeal suturing. Angles of <55 degrees between instruments and the horizontal line simplified laparoscopic suturing, as did angles of <45 degrees between the instruments. In cases of maximally narrowed space (diameter of 4 cm), a suture filament length of <10 cm decreased the time required by 30%.


CONCLUSION
We suggest an isosceles triangle between the instruments with an angle between 25 degrees and 45 degrees and an angle of <55 degrees between the instruments and the horizontal line as the optimal geometry for intracorporeal suturing. These data should be considered when planning a reconstructive laparoscopic procedure (i.e., alignment of trocars, table position). However, further studies are required to confirm these preliminary results.