Reconstruction of traumatic ventral hernias often requires not only the use of abdominal wall component separation, but also the use of interpositional reconstruction with an acellular dermal matrix or other mesh to bridge the defect. We have developed a new value termed the "Component Separation Index" or CSI, to evaluate ventral hernia defects. Choosing a fixed point on a preoperative axial CT scan (aorta) and the medial leading edges of the rectus abdominus muscles, we determined the angle of diastasis of the hernia. This angle is divided by 360 degrees giving a relative value of the transverse defect size as compared to the estimated circular body habitus for that specific patient. The value was then used as a predictor of the need for interpositional repair. A retrospective review of 30 cases of ventral hernia repairs was performed. The CSI was calculated from the pre-operative CT scans obtained prior to repair. Group I (n=15) required component separation for closure. Group II (n=15) required component separation and placement of interpositional mesh to span the hernia defect. The Mean CSI for Group I was .28 with SD of .08. The Mean CSI for Group II was .34 with SD of .05 (P=.019, CI=.33).

To our knowledge there has been no other study utilizing an indexed value for the evaluation of traumatic ventral hernia defects. With the CSI the defect size is translated to a value that corresponds to the patient’s own biometric identity and allows for a standardized method to compare and study ventral hernias and abdominal wall defects. As this value approaches 0.3 the likelihood of an interpositional repair with component separation becomes much greater. We believe this value will help guide the plan for reconstruction of ventral hernias. While there is no substitute for clinical acumen when evaluating these defects, objective measurements can provide a valuable additional tool for the surgeon facing these cases.