The lower extremity IO placement sites from medial to lateral are 1-3cm above the medial malleolus at the distal tibia, 1-3cm below the tibial tuberosity on the flat anteromedial proximal tibia, and 1-3cm above the patella in the midline of the distal femur. Use 1cm for an infant, 2cm for a toddler, and 3cm for a child. See diagram here.