Association between Midline Extraction Incision and Increased Risk of Incisional Hernia Following Minimally-invasive Radical Nephrectomy: Results of an Observational Study from a High-Volume Center.

PURPOSE To determine whether specimen extraction incision and body morphometry analysis of skeletal muscle and fat mass is predictive of incisional hernia (IH) following minimally invasive nephrectomy (laparoscopic or robotic). MATERIAL AND METHODS We conducted an observational study of a prospectively maintained database of patients undergoing minimally invasive nephrectomy from 2005-2022. For inclusion patients were required to have pre-operative and one-year and two-year post-operative abdominal cross-sectional imaging. Skeletal muscle and fat mass indices were calculated based on measurements obtained from preoperative imaging. The location of the specimen extraction incision was determined from operative reports. IH were diagnosed on review of post-operative imaging. Logistic regression analysis was performed to identify predictors of IH. RESULTS 494 patients met inclusion criteria. The most commonly used extraction incisions were Gibson (250 patients, 51%), midline (98 patients, 20%), paramedian (58 patients, 12%), and Pfannenstiel (21 patients, 4.3%). At two-year post-operative follow-up, 59 patients (12%) had developed IH. The incidence of IH was highest among patients receiving midline incision (23%), compared to all other incision types (≤10% each). Baseline fat mass index (OR: 1.18, 95% CI: 1.06-1.32, p=0.002) and a midline extraction incision (OR: 4.60, 95% CI: 2.23-9.48, p<0.001) were independent predictors of IH. CONCLUSIONS A midline extraction incision is associated with a significantly higher risk of IH following minimally-invasive nephrectomy. Body morphometry analysis did not improve predictive models compared to models using body mass index. These data support a prospective trial to identify the optimal extraction incision for hernia-free survival and patient-reported quality of life.