Radiograph showing analysis to ascertain the proximal femoral morphology. Reprinted from Early Post-operative Periprosthetic Femur Fracture in the Presence of a Non-cemented Tapered Wedge Femoral Stem, Cooper HJ et al, 2010, by the HSS Journal: the Musculoskeletal Journal of Hospital for Special Surgery. cortical index = a/b, canal cone ratio = c/d, canal to calcar ratio = c/e, canal-flare index = f/c