3D-printing in preoperative design of internal fixation for Sanders III calcaneal fractures

Objective To investigate the application of 3D-printing and digital technology in the preoperative design of internal fixation for intra-articular calcaneal fractures. Methods Thin-layer CT images of bilateral calcanei were collected from 12 patients who had been treated for calcaneal fracture of Sanders type Ⅲ from November 2015 to October 2016. They were 7 men and 5 women, aged from 23 to 53 years (average, 38.7 years). The images were uploaded into Mimics software for 3D reconstruction, virtual reduction and digital surgical design. Real-size calcaneal models and navigation modules were produced using 3D printing technology for plate preshaping and surgical simulation. The operations were carried out according to preoperative design. The postoperative calcaneal morphological parameters were evaluated. Comparisons were made between postoperative results and preoperative digital design. Results The operating time for the 12 patients ranged from 60 to 90 minutes, averaging 77.9 minutes. Their follow-ups ranged from 4 to 8 months, averaging 6.2 months. No complications affecting their soft tissues happened. The postoperative Bohler angle(32.6°±3.6°) and Gissane angle (123.9°±9.5°) were significantly improved compared with the preoperative values (12.4°±2.1° and 143.9°±7.8°) (P< 0.001). The shape of postoperative calca-neus was similar to that of the preoperative reduction model. The internal fixation locations and nail directions were in agreement with the preoperative design. Their average Maryland score was 87.8 and excellent to good rate 91.7%. Conclusion This technique can transform a digital design for intra-articular calcaneal fracture into real operation tools to help realize a precise surgical design for such fractures. Key words: Calcaneus; Fractures, bone; Fracture fixation, internal; 3D-printing; Preop-erative design