Tracking Technological Change in Liver Surgery: Robotic Adoption and Case-Mix Evolution in the I Go MILS Registry

Background: The adoption of robotic surgery in minimally invasive liver surgery has accelerated globally in the last decade, yet its impact on clinical outcomes and the associated benefits remain to be explored. Methods: The study analyzed 8928 minimally invasive liver resections recorded in the I Go MILS registry between 2015 and 2025. Temporal trends in surgical approach, Pringle maneuver utilization, conversion to open surgery, and postoperative morbidity were assessed using Cochran-Armitage and Spearman tests. Case-mix evolution was quantified by the Kawaguchi-Gayet difficulty score. Results: Robotic utilization increased monotonically from 10.4% to 42.2%, while fully laparoscopic procedures declined from 89.6% to 57.8%. Despite this transition, aggregate conversion and morbidity showed no significant temporal trends. Stratified analysis demonstrated lower observed conversion rates in the robotic group and a progressively narrowing difference in morbidity. Overall case-mix complexity increased significantly, driven exclusively by the laparoscopic arm, while the robotic case mix remained structurally stable. Conclusions: Aggregate outcome stability during the robotic transition suggests progressive case-mix complexification rather than technological stagnation. The robotic platform seems to be associated with an apparent conversion advantage; its higher observed morbidity may be attributable to structural differences in operative difficulty. Robotics act not as a substitute for laparoscopy but as a complementary approach applied to more complex resections.