Current surgical paradigms, including membrane anatomy and stratigraphic surgery, are constrained by a static, structural view of fascial planes and interstitial spaces. This perspective fails to explain the dynamic pathophysiology of postoperative complications and tumor recurrence. We propose Surgical Interstitialogy as a new framework, founded on the Interstitial-Cleft Network (ICN)—a dynamic, fluid-filled continuum connecting cellular microenvironments to macroscopic surgical planes, which has been identified as a recognized physiological entity. This redefines the interstitium as an active physiological system governing mechanical integrity, fluid transport, and cellular communication. Consequently, surgical theory evolves from static "structural anatomy" to dynamic "systems physiology," providing a unified model that explains clinical phenomena, predicts risks, and guides innovation. This marks surgery's irreversible transition from a mechanical craft to a systems science.