Assessment of the Spatial Distribution of Mechanical Properties of the Tissue of Anterior Abdominal Wall at Maximum Functional Load

Abstract

The purpose of the study was to investigate the changes in the mechanical properties of the anterior abdominal wall at maximum functional loads. Materials and methods. The study was conducted on 112 volunteers aged 18 to 49 years old who were examined and treated in the surgical department of the Medical Diagnostic and Treatment Center Medion Poltava for the period from June 2020 to May 2021. There were 60 women (53.6 %), and 52 (46.4%) men. Volunteers were divided into 2 groups: the main group (n=58), which underwent the analysis of movement and deformation changes of the anterior abdominal wall during maximal abdominal inflation during the examination, and the control group (n=54), which were operated laparoscopically due to the schedule. Results and discussion. The results of the study showed the following changes in the mechanical properties of the tissues of the anterior abdominal wall: the average deformation in the longitudinal direction was 6% in the main group and 12% in the control one; deformations in the transverse direction were 3% in the main group and 8% in the control group; deformation in the longitudinal direction exceeded the deformation in the transverse by 38-54% (on average by 46%); the area of the anterior abdominal wall in the main group increased by 10%, and in the control one – by 22% (on average by 16%). During the studies, the anterior abdominal wall underwent greater stresses in the transverse orientation than in the longitudinal one (anisotropy coefficient ~2). The Young s modulus of anterior abdominal wall in the sagittal plane is defined as 23.5±2.6 kPa, while in the transverse – 42.5±7.0 kPa. The mechanical properties of human anterior abdominal wall tissues differed along and across the white line of the abdomen: the modulus of elasticity of anterior abdominal wall tissues, with the same force of impact, in the longitudinal direction is less than the transverse average of 44% (p >0.05). That is, the longitudinal stiffness of the anterior abdominal wall is lower than the transverse one. The maximum strength of the anterior abdominal wall is across the white line of the abdomen, and the greatest elasticity – along. The anterior abdominal wall in women showed increased elasticity compared to men, while the stiffness of the anterior abdominal wall tissue in men in both directions was statistically significantly higher than in women (p >0.05). Conclusion. Reconstruction of the spatial distribution of the mechanical properties of anterior abdominal wall tissues according to the nature of their deformation at maximum functional loads provides an additional opportunity to assess the biomechanics of anterior abdominal wall. The mechanical properties of the musculo-aponeurotic structures of anterior abdominal wall in humans differ in the longitudinal and transverse directions. They have the greatest elasticity in the longitudinal direction, and the maximum rigidity and strength in the transverse direction. The strength of the anterior abdominal wall tissue in men is higher, and the elasticity is less than in women. Changes in the mechanical anisotropic characteristics of anterior abdominal wall tissues at maximum functional loads should be taken into account when performing the anterior abdominal wall alloplasty technique