Preliminary Digital Design For Fixation Implant By Three-dimensional Reconstruction In Dorsal Tibial Plateau Fractures

Objective: To investigate the procedures of digital design for fixation implant in dorsal tibial plateau fractures by medical 3-D reconstruction software Mimics and mechanical drafting program Solidworks.Methods: Lower extremities of 17 Adult corpses were selected for experimental materials, main steps include specimen making, high-speed thin layer CT scans, three-dimensional reconstruction, 3-D data measurement, drafting of Solidworks section, theoretical reduction of the fracture, internal fixation with steel plate and consequence analysis. Molding section of lower extremities were exposed by approaching to posteromedial or dorsolateral tibial plateau, apparatus include bone drill,Kirschner wire, osteotome and bone mallet were used to make mold of tibial plateau fractures, specimen were classified into 2 categories by Khan classification--posteromedial and dorsolateral side. Fragments were fixed by adhesive gel, the rest of 13 lower extremities were identified by steel wire. High-speed thin layer CT scans carried out consequently with scanning layer 0.625mm, all data were collected to Mimics 11.0 via disc, files of mask were compiled after threshold value set up, and three-dimensional reconstruction was through by parameters of optimal, shell reduction 1. Preliminary 3-D moldings were polished for further measurement. Various sections were noted by osseous markers on the rear site of tibial plateau where steel plate are scheduled to be implanted. Mimics was applied to measure the 3-D length and 3-D angle on the scale in those sections. Steel plates and screws were drafted by Solidworks 2008 SPO in accordance with previous data. Theoretical reduction of the fracture achieved by shifting or moving 3-D model under Reposition instruction in Mimics program, then digital internal fixation was accomplished through moving steel plate and screw to the scheduled site under Reposition instruction after stl files uploaded in Mimics program, consequence analysis was done as followed, Solidworks section will be amended when necessary according to the consequence analysis.Result: CT scans, three-dimensional reconstruction, theoretical reduction of the fracture have been carried out smoothly in all cases and 2 kinds of fracture molds. And the measurement of length or angle in 3-D mold was done in accordance with the design and implantation of steel plate. The drafting of Solidworks sections and internal fixation was achieved by 3-D measurement data. What's more, the visual internal fixation of sample, steel plate and screw was carried out in the Mimics. The consequence analysis shows anatomical reduction and excellent internal fixation.Conclusion:1. The design of digital implantation fixation can be carried out by using PC, medical three-dimensional reconstruction software Mimics and Solidwork. 2. Our project may provide relevant evidence for orthopedic instruments development.