Design And Research Of Three-dimensional Printing Guide Template For Internal Fixation Of Complex Subtrochanteric Fractures

Objective: It is increasing that the complex comminuted subtrochanteric fracture by high-energy injury. At present,the internal fixation operation is the main way of treatment.It is often the problem of traumatic orthopaedic surgeons for the clinical treatment because of fractures in patients with complicated and the great differences between individuals. In the therapeutic process, according to his clinical experience the surgeon select the method of internal fixations and the guide wire position and direction in the process of implants placed. Accuracy and safety of this way is insufficient.It is easy to lead some complications which includes implants deviation and internal fixation failure, etc. Therefore, the choice of surgical approach and the accuracy of intraoperative implants placement are the key factors to influence the curative effect and prognosis. Based on this, we design the best operation method and steps by using three-dimensional printing fracture model in this research.We Assist to locate by using three-dimensional printing guide template to increase the security and accuracy in surgery and shorten the learning curve for complicated fracture surgery. It provides a new method and an effective aid for clinical surgery.Methods:1 We selected one patient with complex femoral subtrochanteric fractures, who was 56 years old, weight 78 kg, height 172 cm. X-ray: left comminuted subtrochanteric fracture, SeinsheimerⅤ.The hemivertebrae is 12 thoracic. Philips Brilliance 64-slice spiral CT transverse scanning in supine position was done from the superior border of the pelvis to distal femur.Layer thickness was 1mm. The scanning range included the limb and the contralateral limb. We obtained 326 CT dicom images.2 The images that we has gotten were imported into Mimics 17.0.Using original image, We masked, splited, smoothed to generate digital three-dimensional model of the fracture and contralateral proximal femoral. Meanwhile we reconstructed and labled different fracture blocks separately.3 We reduced the fracture of digital three-dimensional model by virtual surgery in Mimics. We considered multiple factors to use dynamic condyle screw by means of observing and analyzing the digital three-dimensional model before and after fracture reduction.4 We printed out two copies of the fracture model and one copy of the mirror which is the contralateral proximal femoral model. One copie of the fracture model was chose to reduce fracture blocks. We selected suitable length of the dynamic condyle plate and drafted the position and number of the screw.Then surgical operation was simulated in this copy for preliminary shaping the selected implant.5 Parameters in detail of the shaped dynamic condyle screw were measured. Dynamic condyle screw digital model was designed in Creo Parametric 2.0 and imported to 3-matic 9.0. Digital model was putted in the position that accorded with the AO standard for testing the relationship between screws and fixed fracture blocks.6 Based on validation of DCS installation location,we positioned of the guide wire point of compression screw and and proximal cancellous bone screw. Anatomy morphology of cortex bone was extracted around the guide wire point. The reverse template which had been consistent with the cortex bone surrounding the guide wire point was established in the software. The reverse template was printed by three-dimensional printer. Selected another copy of fracture model,we installed the dynamic condylar screw by using guide template to validate the feasibility of surgical guide template.Results:1 Using the patient’s CT images, We masked, splited, filled and smoothed in Mimics 17.0 to generate digital three-dimensional model of the complex subtrochanteric fracture and contralateral proximal femoral. We reduced the fracture of digital three-dimensional model by virtual surgery. The digital three-dimensional model of fracture reduction was obtained. We considered multiple factors to use dynamic condyle screw by means of observing and analyzing the digital three-dimensional model before and after fracture reduction.2 The physical model of complex subtrochanteric fracture was printed in the same size by three-dimensional technology. It provided a realistic preoperative simulation environment.We selected suitable length of the dynamic condyle plate and drafted the position and number of the screw.Then surgical operation was simulated in this copy for preliminary shaping the selected implant and determining the length of the screws.3 Dynamic condyle screw digital model was designed in Creo Parametric 2.0 and imported to 3-matic 9.0 with the digital three- dimensional model of fracture reduction. Digital model was putted in the position that accorded with the AO standard for testing the relationship between screws and fixed fracture blocks. Verification results showed that the plate and screw length was consistent with selection from the fracture model by three-dimensional printer. Parameters of dynamic condylar screw were determined finally. Plate length was 242 mm with 14 holes.Tension screw length was 65 mm. The length of 4.5 mm cancellous bone screw from the proximal to distal were 54 mm, 44 mm. The length of 4.5 mm cortical bone screw from the proximal to distal were 34 mm, 34 mm, 34 mm, 32 mm, 32 mm, 32 mm.4 Based on validation of DCS installation location,we positioned of the guide wire point of compression screw and and proximal cancellous bone screw. Anatomy morphology of cortex bone was extracted around the guide wire point. The reverse template which had been consistent with the cortex bone surrounding the guide wire point was established in the software. The reverse template was printed by three-dimensional printer.5 Surgical operation was simulated on the physical fracture model by three-dimensional printing guide template. This surgical guide template had good abilities of matching and accuracy.The time of simulation operation was shootend. It is suitable for internal fixation of complex subtrochanteric fractures.Conclusion: In this study, complex subtrochanteric fracture model and surgical guide template are built by using of advanced computer-aided engineering software and three-dimensional printing technology.It provided anatomical basis for making the scheme that is individual operation on complex femoral subtrochanteric fractures patients. The learning curve for complicated fracture surgery is shortened. It provides a new method to locate fastly and accurately on opertion for clinical surgery.