Where is the earliest site for intraosseous infusion in emergency care?

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In emergency care, intraosseous access is used when IV access can’t be secured quickly, because the bone marrow cavity can rapidly absorb fluids and meds into the central circulation. The earliest and most reliable site is the proximal tibia on the flat anterior surface, just below the tibial tuberosity. This spot gives easy landmark identification, a relatively thin cortex, and direct access to a large medullary space with fast venous drainage, allowing rapid infusion with minimal tissue disruption. Other sites, like the anterior fibula or the posterior fibula, are not favored because they have smaller marrow spaces and higher risk to nearby nerves and structures, making access slower and less reliable. Insertion above the tibial tuberosity would be too high and nearer the knee joint, increasing risk and complexity.