Introduction Definition the process of anticipating the size and position of implants prior to surgery Importance allows prediction of implant sizes needed to be available in operating room provides a reliable starting point in determining size and position of implants Accuracy up to 92-100% accurate +/- one size Steps obtain appropriate radiographs analyze radiographs for appropriate planning ensure scale is correct between templates and radiographs template femoral component template tibial component Radiographic Views Necessary radiographs AP weight-bearing radiograph of the knee lateral view of the knee most important view for templating patellofemoral joint view not necessary for templating Optional radiographs full-length hip-to-ankle AP weight-bearing view can be used for templating useful for ruling-out extra-articular deformity estimating coronal laxity planning bony cuts with respect to mechanical axis Magnification 20% is standard most templates account for this magnification markers are helpful Radiographic Analysis Step 1 assess the mechanical axis draw a line of the hip-to-ankle view that shows the overall mechanical axis neutral mechanical axis should bisect the center of knee Step 2 estimate magnitude of coronal deformity measure the tibiofemoral angle Step 3 determine the femoral resection angle difference between mechanical and anatomic axis of the femur Step 4 determine tibial bone cut perpendicular to mechanical axis Step 5 assess bony defects and osteophytes easiest to do on AP weight-bearing view Step 6 assess tibial slope completed on lateral radiograph Step 7 assess patellar height completed on lateral radiograph assess for patella baja this will make exposure more difficult Step 8 assess patellar shift/tilt completed on skyline view of patella Template the Femur Steps choose appropriate implant size on lateral radiograph restore posterior condylar offset avoid notching assess this size component on the AP to determine medial/lateral positioning and ensure no overhang if there is significant overhang, may have to consider downsizing Template the Tibia Steps choose appropriate size based on lateral radiograph ensure no overhang aim to match native tibial slope assess this component size on the AP to determine medial/lateral positioning and ensure no overhang consider downsizing if there is any overhang