Biomechanical comparison of post-resection fixation methods in locally aggressive tumors of the distal femur

The knee area is the most common area where locally aggressive tumors are seen. Treatments vary depending on the location and size of the tumor. An ideal treatment has not been described in the literature. In this study, we aimed to biomechanically demonstrate the ideal treatment for defects seen in the distal femur according to the size of the defect. 49 composite femur materials were used in our study. The femur material was divided into seven groups, seven in each group. No procedure was applied to Group 1 (control group). An isolated 50% defect was created in Group 2. An isolated 75% defect was created in Group 3. Cement was applied after a 50% defect was created in Group 4. Cement was applied after a 75% defect was created in Group 5. In Group 6, after a 50% defect was created, two screws were sent to the joint and cement was applied. In Group 7, after a 75% defect was created, two screws were placed parallel to the joint and cement was applied. Then, an axial loading test was applied to the lateral condyle of each femur. Then, the groups were evaluated among themselves. As a result of our study, it was seen that leaving the defect empty or grafting alone after surgery was insufficient in locally aggressive tumors of the distal femur. It was seen that filling with cement alone was sufficient. Screw cementation was not shown to be superior to cementation alone. Different defect sizes did not change the result. Isolated cement application is sufficient to prevent the risk of fracture in small and large defects. In our study, we found that screw application on cement is not necessary because it prolongs the surgical time, increases the risk of infection and the high cost of the implant.