Page 146 - Prevention and Treatment of Incisional Hernia- New Techniques and Materials

Chapter 7
ARM, if a patient had an ileostomy or, if a patient had multiple colostomies. Patients with a parastomal hernia or IH were not excluded from this study.
I-Space®
In order to evaluate a midline shift at the level of the colostomy, the I-Space®, a CAVETM like virtual reality system, and V-scope software were used (16). This system was previously used and validated in a gynecologic and orthopaedic studies (17, 18). The CT-scans were uploaded to the I-Space® PACS, format converted, and then three dimensionally visualised and projected using the V-Scope application. This results in a “hologram” of the dataset being visualised oating in front of the viewers. The viewers wore a pair of lightweight glasses with polarising lenses that allowed the hologram to be seen with depth. A virtual pointer was used to interact with this “hologram” which made it possible to move into the hologram and to perform measurements (Figure 1 and 2) (19). The exact midline of the abdominal wall was determined by drawing a 3-dimensional line between the xyphoid process and the pubic bone, parallel to the spine. The distance of the abdominal rectus muscles to this midline (dARM) was measured to determine how the exact midline corresponded with the position of the rectus muscles. The midline shift was calculated as follows: (left dARM + right dARM) / 2 – left dARM). For instance, if the distance of the right ARM to the exact midline was 4 millimeter (mm) and the distance of the left ARM to the exact midline was 6 mm, this would constitute to: (6 + 4) / 2 – 6 = -1mm, which would mean that the rectus muscles have shifted 1mm to the left at the level of the colostomy.
ARM measurements
Measurements were performed at 5 di erent points at both the colostomy (left) side and the contralateral (right) side in order to evaluate the ARM thickness. These measurements were taken at 8cm, 3 cm cranial and caudal to, and at the level of the colostomy.
Statistical analysis was performed using the paired Student’s t-test, Mann-Whitney-U test and the Spearman correlation coe cient, whenever appropriate(SPSS 14.0, Chicago, IL, USA). Numbers are presented as means with standard deviations (SD) or medians with interquartile ranges (IQR). A p-value of <0.05 was considered statistically signi cant.
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