[Digital design of internal fixation for distal femoral fractures via 3D printing and standard parts database].

Objective: To study the method of internal fixation by the navigation embedded plate from standard parts database for the distal femoral fractures based on digital design by Mimics software with 3D printing technology, and to explore its feasibility and accuracy.
Methods: A total of 21 cases with distal femoral fractures admitted into the Department of Orthopedics, Affiliated Hospital of Putian University were included in this study. Dicom format data of lamellar CT scanning was imported into Mimics software for 3D anatomical modeling and virtual fracture reduction. The steel plates was chose from standard parts database for virtual internal fixation, and to design the navigation module with screw. 3D printing skeleton, steel plates, navigation module, internal fixation implants were simulated based on the printed bones model. Locations of steel plates and screws were determined by the navigation module. Then the sticking effects of navigation module, screws position and postoperative appearance were observed. After second CT scan and 3D reconstruction, 3D registration was performed to obtain the data of the three-dimensional coordinate values of screws entrance points and piercing points to analyze the results.
Results: A total of 21 plates and 180 screws were placed with the assistance of navigation module. CT scanning and 3D reconstruction was performed in twenty-one cases of postoperative bone model. The position of plates was in high accordance with the digital design by Mimics software. There were no significant differences between spatial location of screw entrance points and piercing points. The real operation was quite consistent with preoperative design. Navigation module and the corresponding distal femur bony structure jointed closely. The sticking effects and stability of navigation module were good, which was able to guide placement of steel plates and screws.
Conclusion: These methods can enhance the accuracy of internal fixation of the standard parts database steel plate in distal femur fractures, with the assistance of navigation module.