Three-dimensional hernia analysis: the impact of size on surgical outcomes

BMI and hernia defect size are strongly associated with outcomes after open ventral hernia repair (OVHR). The impact of abdominal subcutaneous fat (SQV), intra-abdominal volume (IAV), hernia volume (HV), and ratio of HV to intra-abdominal volume (HV:IAV, representing visceral eventration) is less clearly elucidated. This study examines the interaction of multiple markers of adiposity and hernia size in OVHR.

OVHR with preoperative CT scans were identified. 3D volumetric software measured HV, SQV, IAV, and HV:IAV was calculated. A principal component analysis was performed to create new component variables for collinear variables. Hernia PC was composed primarily of hernia dimensions, EAV (extra-abdominal volume PC) included SQV and BMI, and IAV PC included IAV.

A total of 1178 OVHR patients had a preoperative CT scan. Their demographics included a mean age of 58.5 ± 12.4 years, BMI of 34.2 ± 7.7 kg/m², and 57.8% were female. The mean defect area was 150.8 ± 136.7 cm², and 66.0% were recurrent, Patients had mean SQV of 6719.4 ± 3563.9 cm³, HV of 966.9 ± 1303.5 cm³, IAV of 4250.2 ± 2118.1 cm³, and a HV:IAV of 0.29 ± 0.46. In multivariate analysis, Hernia PC was associated with panniculectomy (OR 1.52, CI 1.37-1.69) and component separation (OR 1.34, CI 1.21-1.49) and was negatively associated with fascial closure (OR 0.78, CI 0.69-0.88). Hernia PC was also associated with reoperation, readmission, and development of wound complications (OR 1.18, CI 1.08-1.30; OR 1.15, CI 1.04-1.27; OR 1.28, CI 1.16-1.41, respectively). EAV PC was associated with performance of a panniculectomy (OR 1.33, CI 1.20-1.48), readmission (OR 1.18, CI 1.06-1.32), and wound complications (OR 1.41, CI 1.27-1.57). IAV PC was not associated with adverse outcomes.

Values of hernia area, volume, IAV, HV:IAV, BMI, and SQV are collinear markers of patient obesity and hernia proportions. They are distinct enough to be represented by three principal component variables, indicating more nuanced discrete influences on variability of surgical outcomes other than BMI.