A and B, Type I femoral deficiency: minimal loss of metaphyseal cancellous bone and intact diaphysis. C and D, Type II femoral deficiency: extensive loss of metaphyseal cancellous bone and intact diaphysis. E and F, Type IIA femoral deficiency: metaphysis is severely damaged and nonsupportive, with greater than 4 cm of intact diaphyseal bone available for distal fixation. Horizontal lines on radiograph demarcate amount of femoral isthmus available for distal fixation. G and H, Type IIIB femoral deficiency: metaphysis is severely damaged and nonsupportive, with less than 4 cm of diaphyseal bone available for distal fixation. Horizontal lines on radiograph demarcate amount of femoral isthmus available for distal fixation. I and J, Type IV femoral deficiency: extensive metaphyseal and diaphyseal damage in conjunction with a widened femoral canal. Isthmus is nonsupportive.