Figure 2a – photograph showing the adolescent-sized composite femoral model. The identical specimens measured 45 cm in length with a central canal diameter of 10 mm, each with an identical fracture 10 mm in length with identical spiral and fragment angles. This photograph was taken after implantation of the two 3.5 mm nails, with the fracture again distracted as shown in order to visualise the configuration inside the medullary canal. Figure 2b – radiograph of a control femoral model with retrograde intramedullary fixation, showing two 3.5 mm steel nails implanted in the classic 2-C-shaped configuration.