Computer-aided anatomical analysis with the DICOM protocol is the most widely used medical imaging standard for the study and transfer of images [20-22]. This technology allowed us to examine the positions of different points of the abdominal viscera induced by different decubitus positions [13-15]. Our results are both descriptive and quantifiable. To perform interventions in laparoscopic surgery, the patient is positioned in decubitus to make the viscera targeted for the surgery more accessible . However, the use of these decubitus positions is intuitive and is based on the positioning of organs [14,16]). Our results were not homogeneous, so the mobility of the different points studied could be related to more than one factor, such as fixations to the peritoneum and the proximity of other viscera.
Limitations of the study could include the small number of cadavers used and the method of fixation. Regarding the first, the performance of ten series in each of the three cadavers significantly increased the sample size of our study, so we consider the total number of measurements sufficient to initially assess the movements of the colon. Regarding the second point, the Thiel technique is the fixation technique used for training models for laparoscopic surgery [19,23]. Since it does not make the cadaver excessively stiff, it is considered ideal for the study of the mobility of the abdominal viscera .
Our descriptive results are difficult to systematize when compared with the individual characteristics of the colon. Cadaver 1 had the longest colon and had the largest number of modified variables. Cadaver 2 had a very short colon and an intermediate number of modified variables. Finally, the colon of cadaver 3 had an intermediate length and the fewest modified variables. These results do not support the hypothesized relationship between size of the colon and the changes in the variables.
The correlations between the pubis and the mesenteric arteries and the mesenteric arteries with themselves suggest that when the distance from the pubis to the inferior mesenteric artery is modified, the distance and direction from the pubis to the superior mesenteric artery also changes. However, the distance from the pubis to the superior mesenteric artery and from the pubis to the inferior mesenteric artery is related to the distance between the two mesenteric arteries, although in a different direction. This leads us to propose that the distance between the two arteries tends to compensate for variations in the distance from the pubis to the superior mesenteric artery. Thus, the inferior mesenteric artery point could be more mobile than the superior mesenteric artery point. This proposal can be explained by the fact that the superior mesenteric artery is pinched by the pancreas at its outlet, increasing the mobility of the inferior pancreaticoduodenal artery as it enters the mesentery artery [1-4]. These three characteristics make the superior mesenteric artery more limited in its movements than the inferior mesenteric artery, which simply attaches to the parietal peritoneum [1-4].
According to the correlation test, the angle between the inferior mesenteric artery and the colic flexures increases as the distance from the mesenteric artery exceeds the hepatic flexure and vice versa. The hepatic flexure is in direct contact with the renal fascia since the peritoneal folds that attach it to the posterior wall are very short; this configuration confers limited mobility. In contrast, the splenic flexure is attached to the wall by the phrenicocolic ligament, which is a longer peritoneal fold and thus allows more mobility (Gallot, 2006; Bourgouin et al., 2012; Barussaud et al., 2015; Gao et al., 2017). Therefore, when the inferior mesenteric artery is mobilized, the angle formed between it and the colic flexures is more closely related to the distance between the artery and the hepatic flexure, which has a fixed end, than to the distance from the splenic flexure, whose two extremes are more lax.
The variables related to the angle between the superior mesenteric artery and the colic flexures changed in different directions, and a high correlation index was not obtained. This may be because, as noted above, the superior mesenteric artery point depends on the pancreas, the pancreaticoduodenal artery outlet, and the mesenteric root, making it difficult to predict their movements in relation to the hepatic and splenic flexures (Gallot, 2006; Bourgouin et al., 2012; Barussaud et al., 2015; Gao et al., 2017).
The variables related to the angle between the pubis and the colic flexures were the least modified, possibly because the pubis is a fixed point just as the hepatic flexure is and the size of this angle is inversely related to the displacements of its most mobile point, such as the splenic flexure. This may explain the high correlation index between the angle formed by the pubis and the colic flexures and the distance from the pubis to the splenic flexure.
Changes in the position of certain segments of the colon have been identified during virtual colonoscopy studies when the patient changes from supine to prone position (Rottgen et al., 2005; Punwani et al., 2009; Pirlet et al., 2014). These changes may be due to the need for insufflation of the colon to carry out the study. In fact, in endoscopic studies, the lateral decubitus position can be changed to the supine decubitus position to achieve a better intraluminal approach to the colic frame (Rottgen et al., 2005).
Laparoscopy is currently the technique of choice for most surgical procedures on the colon. Many studies have been published comparing laparoscopic surgery with open surgery and showing the benefits of laparoscopic surgery (Weeks et al., 2002; Wong et al., 2012). The series established in the working protocol reproduced the different postural changes performed during surgery. The aim of lateral decubitus positioning is to displace the intestinal loops towards the corresponding side, obtaining a good exposure of the colon, and to attempt greater medial displacement of the hepatic flexure or the splenic flexure (according to the side) when performing correct traction. More mobile points, such as the ileocecal junction or even the descending colon-sigmoid junction, may have greater displacement (Sadler et al., 2007; Shimizu et al., 2016). Regarding our proposal, our quantitative results are imprecise. However, the correlation analysis allowed us to relate the displacements of the studied points to one another. In this way, we have associated these displacements with the mobility of the points according to their insertion in the peritoneum. A short insertion allows little mobility (hepatic flexure), in contrast with a long insertion (splenic flexure) or a less fixed insertion (inferior mesenteric artery). When the point studied was related to additional factors, such as the proximity of another organ or vessel (superior mesenteric artery), the displacement was more difficult to determine. Thus, when a distance is defined by a fixed point and a moving point, it is easier to determine its angle than if the segment is delimited by two moving points.