The long bone nonunions and critical bone defects are two of the more difficult complications to treat. We treated a 59 years old patient that came to our attention through the ambulatory of nonunion of our institute with a diagnosis of distal femoral nonunion on the left side: the patient had undergone previous osteosynthesis with plate and screws. At admission the NUSS score of the patient was calculated in order to orientate on the therapeutic strategy to be adopted. It was decided to follow the principles of monotherapy, proceeding with the resection of necrotic bone and the subsequent installation of bone morphogenetic proteins (BMP-7). The postoperative course was smooth; it took a long motory rehabilitation period but, a year after surgery, the patient has achieved a good functional recovery, reaching a good quality of life.