Application of three-dimensional stereography to assess abdominal wall mobility

Abstract

Functional impairment of the abdominal wall can cause serious discomfort in patients, even during daily activity. We introduce a new method to describe and calculate abdominal wall mobility and its disturbances. The abdominal wall compliance can be measured non-invasively by three-dimensional stereography. Three-dimensional stereography is an optical method for measuring the topography of surfaces. The deformation of a light grid projected onto the abdominal wall is documented by video. After automatic digitisation of the pictures the computer calculates changes of the surface area. The abdominal wall mobility can then be measured by comparing the abdominal surface changes in minimum and maximum excursions. Measurement of defined geometric bodies proved the accuracy of our method with a variation under 5%. We found an abdominal wall mobility in normal persons (n=21) of 5.4 cm ± 1.9 for height difference, 2.6 1/100 cm ± 1.4 for the minimum curvature difference, 6.2 1/100 cm ± 1.8 for the maximum curvature (p<0.01), 110 cm ± 74 for the adjusted radius at minimum excursion and 41 cm ± 14 at maximum excursion (p<0.01). This method allows us to calculate abdominal wall compliance and its restriction. Comparison of pre- and postoperative data could help us to assess the success of operations concerning the abdominal wall.