Cornering: A Geometric Framework for Surgical Dissection in Minimally Invasive Surgery.

BackgroundPrecise tissue dissection is a fundamental component of minimally invasive surgery (MIS), yet it is often taught implicitly. While triangulation and traction-countertraction are widely recognized as geometric principles for exposure and transection, the geometric conditions that enable the dynamic advancement of dissection along tissue interfaces have not been clearly articulated.MethodsWe performed a schematic geometric analysis of surgical dissection focusing on the relationships among traction direction, opposing tissue surfaces, and the dissecting edge. Based on this analysis, we introduce Cornering as a conceptual framework describing how dissection advances along the intersection of 2 tissue planes through the active formation and maintenance of a dissectable edge under tension. We further define planarization as the local geometric state in which tissue becomes suitable for controlled division, and decornering as the terminal transition where opposing planes resolve into a continuous surface.ResultsCornering highlights that effective dissection depends on maintaining an appropriate three-dimensional dihedral angle between opposing surfaces, allowing the dissecting edge to remain in a planarized state. Within this framework, inefficient or unsafe dissection is interpreted as insufficient traction, inappropriate angulation, or loss of effective depth. Two modes of Cornering are identified: surface-based Cornering between tissue planes and axis-based Cornering along cylindrical structures.ConclusionsCornering provides a geometric framework that formalizes surgical dissection as a reproducible process. By extending established principles such as triangulation and traction-countertraction, it offers a practical and visually interpretable model that may support surgical education, intraoperative assessment, and technique standardization in MIS.