Postoperative lateromedial (Fig. 7a) and craniocaudal (Fig. 7b) radiograph of the distal part of the left femur after the injection of two specific, but different biomaterials. While bone cement (Fig. 7b) reveals immediate radiodensity, a biomaterial based on hydrogel and without radiopacifier cannot be visualized immediately after surgery. If bone formation takes place over time, radiodensity will increase gradually.