Designing femur medial condyle plate and biomechanical evaluation

Purpose: Our purpose of this study is to design an anatomic locked plate appropriate for bone and soft tissue anatomy of distal femur medial condyle. Methods: Computed tomography was performed on 16 dry cadaver femur bones of different sizes obtained from the anatomy laboratory. Solid modeling of the bones was made with the data obtained. The medial condyle plate of the distal femur was designed in digital environment on solid models, taking into account anatomical structures. Then, ffnite element analysis was performed on the plate that was planned to be produced. The produced plate was subjected to 4 different biomechanical tests by making AO / OTA 33A3 type supracondylar fracture model on artificial femur bones. Samples were divided into 3 equal groupsGroup A samples were fixed from the medial with the distal femur anatomic locking plate (manufactured by us), group B samples were laterally with the distal femur anatomical locking plate, and the C samples were fixed from both medial and lateral using double plates. 62 pieces sawbones and 80 pieces plates (40 medial, 40 lateral) were used totally. Axial compression, cyclic axial compression, load to failure and 3- point bending values were measured and compared between groups. Results: In the axial compression test, it was observed that the model structure integrity was preserved 23% more in group C than in group B. In the cyclic axial compression test, bone fracture was observed in group A in 11000 cycles. No bone fracture was observed in the other groups. While total displacement was 21% less in group C than in group B, 47% less displacement was seen in bone without osteotomy. In the load to failure test, it was observed that failure developed in Newton values 6% higher in group B than in group A. It was observed that the failure developed in the Newton values that were 51% higher in the C group compared to the A group and 49% higher than the B group. In the 3-point bending test, there was a significant difference in displacement values between groups A and C after the load applied in the anterior posterior and lateral medial planes. Conclusion: In our study, it was observed that the application of a locked medial plate in addition to the lateral plate in the AO / OTA 33A3 type comminuted supracondylar femur fracture significantly increased the fracture stability. We recommend the additional application of the medial locking plate designed for the medial femoral condyle in such fractures.