Morphometric evaluation of the linea alba in fresh corpses

Abstract

Purpose: Diastasis recti abdominis is an increase in the distance between the medial borders of the two rectus muscles. It is most often triggered after intra-abdominal pressure increases, such as postpartum or in obesity. Most publications are based on radiological studies or are done in certain subgroups, without unanimous reference values of the distance between the rectus abdominis or standardization.

Methods: Forty-one cadavers were studied. Exclusion criteria: signs of abdominal trauma, major burns, presence of scar from previous abdominal surgery, clinical signs of abdominal hernia, and identification of hernia during cadaver dissection. Linea alba (LA) length, width, and thickness were measured with a flexible tape measure and digital caliper. Anatomical landmarks were established, and subdivisions were described based on them to compare the cadavers.

Results: Sex and age had little effect on LA width, thickness, or length. Obesity (compared to normal weight) was the only variable that promoted an increase in the LA width (p < 0.01). The supraumbilical length varied with the total height of the evaluated cadavers (p < 0.01), but the infraumbilical length did not (p = 0.11).

Conclusion: The general statistical results of this study, regarding the evaluation of LA measurements in cadavers, showed that ethnicity, sex, and age have little effect on the width, thickness, or length of the LA. LA width differed significantly with abdominal circumference.

Keywords: Abdominal rectus muscle; Diastasis recti abdominis; Intra-rectus distance; Linea alba.

Figure 1

Materials used during the evaluation of the linea alba, focusing on the evaluation of width, thickness, and length. Evaluation of the length of the linea alba with a flexible tape measure and the thickness and width of the linea alba with a digital caliper.

Figure 2

Anatomical references and intervals for comparison between the study subjects. Reference points for linea alba evaluation: xiphoid process (Point A), upper border of the umbilicus (Point B), lower border of the umbilical scar (Point C), and upper border of the pubic symphysis (Point D). Reference intervals for comparison between subjects: total length from the xiphoid process to the pubic symphysis (Interval A-D). Supraumbilical length: from the xiphoid process to the upper edge of the umbilicus (Interval A-B). Circumference of the umbilicus and umbilicus diameter (Interval B-C). Infraumbilical length: from the lower border of the umbilicus to the pubic symphysis (Interval C-D).

Figure 3

Illustrative diagram showing mean and standard deviation on pre-established points and intervals on linea alba. In the picture, the pre-stablished points are shown in full lines and over dotted lines, we measure the length on the intervals shown in previous pictures.

Figure 4

Analysis of the midpoints of the supra- and infraumbilical measurements according to abdominal waist circumference (stratified by obesity classification for abdominal circumference). *ANOVA followed by Tukey's test. Supraumbilical width: eutrophic vs. obese: p = 0.02. Infraumbilical width: eutrophic vs. obese: p 〈 0.01; overweight vs. obese: p = 0.03. Total width: eutrophic vs. obese: p < 0.01; overweight vs. obese: p = 0.01. Other comparisons: p 〉 0.05.