A Comparative Study of Surgical Outcomes Following Onlay and Underlay Repairs for Ventral Hernias

Abstract

Introduction: Today, a variety of procedures are available for ventral hernia repair. Prosthetic reinforcement is necessary in all but the smallest of hernias to reduce recurrence rates. However, the ideal site of mesh placement for better outcomes in open repair has not been established in literature. Aim: To compare onlay and underlay (either retrorectal or preperitoneal) techniques in adults, with respect to operative parameters and treatment outcomes, and to determine the associated prognostic factors. Materials and Methods: This prospective, observational study was conducted from January 2012 to January 2015 at Bangalore Medical College and Research Institute; 199 patients with midline ventral hernias (primary or following first recurrence) with defect size less than 10cm and scheduled to undergo mesh repair were selected. Demographic data, relevant comorbidities, body mass indices and hernia characteristics were noted preoperatively. Type of repair was decided by the attending surgeon based on clinical judgement. Operating time, post-operative pain, woundrelated complications and duration of hospitalization were recorded. Patients were followed-up for two years to detect recurrence. Statistical analysis was performed using one wayANOVA to compare means and Chi-square test, to determine association between categorical variables. p-value <0.05 was considered statistically significant. Results: Mean age at presentation was 44.3±12.90years. Females comprised 77.9% of cases. Primary hernias constituted 66.3%. Mean follow-up period was 15.9±8.39months. Onlay repair was performed in 56.3% whereas retrorectal and preperitoneal in 22.6% and 21.1% cases, respectively. Significantly shorter operating time (in minutes) was noted with onlay (48.8±8.63) compared to retrorectal (59.0±15.47) and preperitoneal (64.5±16.00) repairs (p<0.001). Differences in pain scores were not statistically significant. Incidence of surgical site occurrences (SSO) and length of hospitalization were significantly higher with onlay repair (p-values 0.005 and <0.001, respectively). Statistical significance was not evident when comparing recurrence rates at 1year follow-up. Obesity, diabetes and previous surgery were associated with significantly higher SSO rates, pain scores and duration of hospital stay. Conclusion: Compared to onlay, underlay repairs have significantly lower wound-related complications and may be considered the procedure of choice over other open techniques for small, uncomplicated ventral hernias. Obesity, diabetes and prior surgery are important risk factors adversely affecting surgical outcomes.

Keywords

• onlay repair
• risk factors
• wound complications