Subjects: Medicine, Pharmacy >> Preclinical Medicine submitted time 2017-12-27 Cooperative journals: 《南方医科大学学报》
Abstract： Objective To explore a new method for finite element modeling to achieve material property assignment based on in situ CT gray value in simulated osteotomies for deformities. Methods A CT scan dataset of the lower limb of a patient with extorsion deformity was obtained for three-dimensional reconstruction using Mimics software and preparing a solid model. In the CAD software, the parameters for osteotomy simulation were defined including the navigation axis, rotation angle and reference plane. The tibia model was imported to the FEA pre-processing software for meshing procedure and then exported to Mimics. All the segments of the tibia meshed model were assigned uneven material properties based on the relationship between CT gray values and material properties in the Mimics software. Finally, all the segments of the tibia model, reference axis and reference plane were assembled in the pre-processing software to form a full finite element model of a corrected tibia, which was submitted to resolver for biomechanical analysis. Results The tibia model established using our modeling method had inhomogeneous material properties based on CT gray values, and was available for finite element analysis for the simulation of osteotomy. Conclusions The proposed finite element modeling method, which retains the accuracy of the material property assignment based on CT gray value, can solve the reposition problem commonly seen in modeling via the routine method of property assignment and provides an efficient, flexible and accurate computational biomechanical analysis method for orthopedic surgery.
Subjects: Medicine, Pharmacy >> Preclinical Medicine submitted time 2017-12-27 Cooperative journals: 《南方医科大学学报》
Abstract： Objective To evaluate the clinical effect of 3D printing-assisted minimal invasive surgery on pelvic fracture by plate internal fixation through a small incision lateral to the rectus abdominis. Methods This retrospective study was conducted among 50 patients with pelvic fracture undergoing anteromedial plate internal fixation between September, 2013 and June,2015. Thin-layer computed tomography scan data of the patients were input into Mimics software in DICOM format for 3D editing and virtual surgery before the operation. The pelvic model was created by 3D printing. Simulated operation was performed to design the optimum location of the plate screw, prelflex of the plate, screw length measurement and screwing approach. Diaplasis and internal fixation were performed through the extraperitoneal space with a small incision lateral to the rectus abdominis. Matta standard was employed for diaplasis evaluation, and Majeed assessment was used for function evaluation 6 months after the operation. Results According to Matta standard, excellent and good diaplases were achieved in 96% of the cases, as compared with 94% according to Majeed assessment. Radiographic examination showed a good consistency between the internal fixation and simulated operation. No screw entry into the hip joint cavity occurred in these cases. The mean operation time was 127 min in these cases with a mean intraoperative blood loss of 728 mL and a mean incision length of 8.4 cm. Based on the postoperative VAS score, 12 patients reported severe pain, 28 reported moderate pain and 10 reported mild pain. All the patients were advised for early functional exercise after the operation and clinical healing was achieved in a mean of 8 weeks. Conclusions 3D printing with simulated operation can improve the accuracy and safety of the operation. Preoperative simulation of plate preflex and screw length measurement can shorten the operation time. A small incision lateral to the rectus abdominis allows minimally invasive operation for pelvic fractures.
Subjects: Medicine, Pharmacy >> Preclinical Medicine submitted time 2017-12-07 Cooperative journals: 《南方医科大学学报》
Abstract： Abstract: Objective To investigate the application of 3D printing and digital technology in preoperative assessment and planning of internal fixation surgery for complex tibial plateau fracture. Methods Complex tibial plateau fractures and commonly used plates for tibial plateau were imaged using computed tomography (CT) to reconstruct the 3D fracture and plate models. The 3D models were used to perform virtual reduction and preoperative planning of internal fixation surgery with the most appropriate plates assisted by the 3D library of plates. According to the optimal plan, the 3D physical models of tibial plateau fractures and plates were 3D printed to simulate internal fixation operation. The effects of internal fixation were compared between the virtual surgery and the simulated surgery based on the 3D models. Results The effects of internal fixation in the simulated surgery based on the 3D models were consistent with those of the virtual surgery. No significant difference was found in the screw length between the two surgeries. Conclusion The combination of 3D printing and digital design can improve the effects of internal fixation for complex tibial plateau fractures.
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