Study protocol for a randomized controlled trial for anterior inguinal hernia repair: transrectus sheath preperitoneal mesh repair compared to transinguinal preperitoneal procedure

Background: Anterior open treatment of the inguinal hernia with a tension-free mesh has reduced the incidence of hernia recurrence. The Lichtenstein procedure is the current reference technique for inguinal hernia treatment. Chronic pain has become the main postoperative complication after surgical inguinal hernia repair, especially following Lichtenstein. Preliminary experiences with a soft mesh positioned in the preperitoneal space (PPS) by transinguinal preperitoneal (TIPP) or total extraperitoneal (TEP) technique, showed promising results considering the reduction of postoperative chronic pain. Evolution of surgical innovations for inguinal hernia repair led to an open, direct approach with preperitoneal mesh position, such as TIPP. Based on the TIPP procedure, another preperitoneal repair has been recently developed, the transrectus sheath preperitoneal (TREPP) mesh repair. Methods: The ENTREPPMENT trial is a multicentre randomized clinical trial. Patients will be randomly allocated to anterior inguinal hernia repair according to the TREPP mesh repair or TIPP procedure. All patients with a primary unilateral inguinal hernia, eligible for operation, will be invited to participate in the trial. The primary outcome measure will be the number of patients with postoperative chronic pain. Secondary outcome measures will be serious adverse events (SAEs), including recurrence, hemorrhage, return to daily activities (for example work), operative time and hospital stay. Alongside the trial health status, an economic evaluation will be performed. To demonstrate that inguinal hernia repair according to the TREPP technique reduces the percentage of patients with postoperative chronic pain from 12% to <6%, a sample size of 800 patients is required (two-sided test, a = 0.05, 80% power). The ENTREPPMENT trial aims to evaluate the TREPP and TIPP procedures from patients' perspective. It is hypothesized that the TREPP technique may reduce the number of patients with any form of postoperative chronic pain by 50% compared to the TIPP procedure.