Robot-assisted total mesorectal excision for rectal cancer:case-matched comparison of short-term surgical and functional outcomes between the da Vinci Xi and Si

Background: Robotic rectal resection with da Vinci Si has some technical limitations, which could be overcome by the new da Vinci Xi. We compare short-term surgical and functional outcomes following robotic rectal resection with total mesorectal excision for cancer, with the da Vinci Xi (Xi-RobTME group) and the da Vinci Si (Si-RobTME group). Methods: The first consecutive 30 Xi-RobTME were compared with a Si-RobTME control group of 30 patients, selected using a one-to-one case-matched methodology from our prospectively collected Institutional database, comprising all cases performed between April 2010 and September 2016 by a single surgeon. Perioperative outcomes were compared. The impact of minimally invasive TME on autonomic function and quality of life was analyzed with specific questionnaires. Results: The docking and overall operative time were shorter in the Xi-RobTME group (p < 0.001 and p < 0.05 respectively). The mean differences of overall operative time and docking time were −33.8 min (95% CI −5.1 to −64.5) and −6 min (95% CI −4.1 to −7.9), respectively. A fully-robotic approach with complete splenic flexure mobilization was used in 30/30 (100%) of the Xi-RobTME cases and in 7/30 (23%) of the Si-RobTME group (p < 0.001). The hybrid approach in males and patients with BMI > 25 kg/m 2 was necessary in ten patients (45 vs. 0%, p < 0.001) and in six patients (37 vs. 0%, p < 0.05), in the Si-RobTME and Xi-RobTME groups, respectively. There were no differences in conversion rate, mean hospital stay, pathological data, and in functional outcomes between the two groups before and at 1 year after surgery. Conclusion: The technical advantages offered by the da Vinci Xi seem to be mainly associated with a shorter docking and operative time and with superior ability to perform a fully-robotic approach. Clinical and functional outcomes seem not to be improved, with the introduction of the new Xi platform.