Cortical Cross-Section Porosity — RANKL/OPG Remodeling Map

This simulation looks end-on through a ring of cortical bone — the same transverse view a micro-CT slice or histology cross-section shows — and models the cellular process that actually causes osteoporosis: not a single "bone loss event," but many independent Basic Multicellular Units (BMUs), each drilling and refilling a Haversian canal seen here as a small circle in the bone ring. An osteoclast cutting cone widens a circle, then an osteoblast closing cone narrows it back — and the RANKL/OPG ratio slider controls how large each cut grows and how much the refill lags behind it. Push the ratio up (mimicking postmenopausal estrogen loss or chronic kidney disease-related bone disorder) and canals stop fully closing, so cortical porosity climbs year over year; add an antiresorptive dose and watch the same BMUs swing back toward balance. Live readouts track porosity, simulated years, active BMU count and the net micron balance per remodeling cycle.