| BackgroundClassification is a logic way to know the natural law. An excellent fracture classification system can accurately describe the fracture characteristics, make the material of fracture methodical and systematic, guide treatment, determine the choice of treatment, predict the therapeutic effect and become a tool for education and training. Traditionally, surgeons classified fractures based on X-ray film, text description of fracture classification system and plane fracture atlas. This required the mental analysis and integration of two-dimensional(2D) information into a three-dimensional(3D) concept because the skeleton is a 3D object. To translate the 2D image information into a 3D concept may be difficult and may lead to an incorrect diagnosis. In recent years,3D images were easy to obtain. However, the schematic diagram of fracture classification system did not make progress. It is embarrassing when one surgeon classify acetabular fractures with 3D images referencing a 2D schematic diagram. Therefore, it is necessary to establish a 3D schematic diagram of fracture classification system.Digital medicine is a new interdisciplinary subject which comprises medicine, life sciences, electronics and information science, mechanical engineering, etc. The main features are the combination of medicine and digital high-tech. Digital orthopaedics research mainly includes three aspects:digital orthopaedic anatomy, digital orthopaedic surgery and orthopaedic virtual teaching. Establishment of fracture classification model database is an important content of digital orthopaedic surgery. The purposes of fracture classification system are to describe the fracture characteristics, make the material of fracture methodical and systematic, guide treatment, determine the choice of treatment, predict the therapeutic effect and become a tool for education and training. Correct classification of fracture is a precondition for choosing a therapy. Establishment of fracture classification model database is one of the foundations of virtual surgery training. This can make the virtual surgery training more normalized, programmed and standardized.Currently, orthopaedic virtual simulation system is the research focus in digital orthopaedic surgery. Virtual reality (VR) technology in virtual surgery is the most active area which can help to perform operation, conduct preoperative planning and simulate surgery. Surgical training is an important part of the growth for a doctor. The traditional orthopaedic trauma surgical training mainly practiced in the cadavers and patients. There were many disadvantages such as limited number, poor repeatability and less practice opportunity. Therefore, it is important to seek a new surgical training method which has the characteristic of approach reality, unlimited number and repeated practice. Virtual surgery is a new branch of science which establishes a virtual environment using various medical imaging data and VR technology. User can conduct preoperative planning, simulate surgery and execute operation training in the virtual environment. In the virtual training environment, trainers immersed in the virtual scene, roaming observed 3D structure and learnt various practical technologies through the visual, touching, smelling, auditory perception. Thus the medical students or young doctors may grow rapidly.Normalization, program and standardization are important requirements for surgical training. Traumatic fracture was diversity and variety. The choices of surgical method and internal fixation were remarkable difference. How to make the young doctor quickly and correctly grasp surgical method and choice of internal fixation was an important content of doctor’s growth. With fracture classification system, doctors can make the corresponding decisions about surgical approaches, fracture reduction and choice of internal fixation according to the specific type of fracture. Therefore, fracture classification system being introduced trauma fracture virtual surgery is benefit to the establishment of standardization to virtual training system.Objective1. To establish a set of 3D digital model of fracture classification system and provide a novel and useful tool for medical teaching and clinical work. Meanwhile, establishment of 3D digital model of fracture classification system is the basis of digital orthopaedic surgery.2. To establish a set of 3D digital model of surgical instruments and internal fixation devices for the need of virtual orthopaedic surgery.3. To establish virtual surgery systems of fracture classifications, provide a new platform for orthopaedic surgery training and make the virtual surgery training more normalized, programmed and standardized as well as provide a new tool for preoperative planning and doctor-patient communication.Methods1. Establishment of 3D digital fracture classification model. Three volunteers were selected. Volunteers 1, male,35 years old, height 171cm, weight 70kg; Volunteer 2, male,42 years old, height 175cm, weight 73kg; Volunteer 3, female,32 years old, height 165cm, weight 58kg. Three volunteers were scanned by 16-slice spiral CT scanner. Scanning conditions:voltage 120～140kV, thickness 7.5mm, reconstruction thickness 0.625mm, matrix 512 X 512. Scanned images were saved in DICOM (Digital Imaging and Communications in Medicine)format and burned to CD-ROM disc. The DICOM data were then imported into software Mimics (Materiaise’s interactive medical image control system) 10.01. The imported image information included bone and soft tissue. With the thresholding process, the target bone was differentiated from surrounding soft tissues.3D reconstruction model of the target bone was calculated and then be smoothed. With the simulation function of the software, fracture lines and fragments can be created in the digital mode according to text description of fracture classification system and plane fracture atlas. The fracture model can be moved, rotated and turned transparent. Each fracture fragment can be assigned a different color. Screen-captures of fracture model were saved from anterior, medial, posterior, lateral, etc, respectively. The screen-captures were arranged and printed in order to facilitate the comparison with the traditional 2D schematic diagram. In addition, the software offers the opportunity to record the rotation in the form of video sequences. The videos were exported as.avi video files.2. Establishment of 3D digital model of surgical instruments and internal fixation devices. For the surgical instruments and internal fixation devices with relatively simple structure, such as guide pin, sleeve, bit, periosteal elevator, osteotome, bone knife, cancellous bone screw, gasket, etc, sizes were measured with vernier caliper. In UG4.0 modeling module, with the characteristic operation, forming characteristics and using sketches function of the software,3D model of surgical instruments and internal fixation devices was built. For the surgical instruments and internal fixation devices with relatively complex structure, such as locking compression plate, locking screw, etc, manual measurement was not easy or measured data were prone to error. The surgical instruments were scanned by 3DSS binocular series of three-dimensional optical scanner. The point cloud data were imported into software and treated by gridding. Then,3D model of surgical instruments and internal fixation devices was built in the software.3D digital model needed a certain degree of simplification or rendering to meet the specific requirements.3. Establishment of virtual surgery systems of fracture classifications. Fracture model and device model were exported as STL format. Then data were imported into FreeForm Modeling System. Using the force feedback device, doctor can conduct virtual fracture operation simulation. Utilizing the software GHOST of FreeForm Modeling System, softwares of virtual cutting, fracture reduction and fixation were developed. Using the force feedback device PHANTOM, doctor can manipulate virtual surgical instruments and fracture classification model and simulate surgical actions such as assembly of surgical instruments, drilling, implantation of screw, reduction of fracture, bone grafting, fracture fixation, etc. A separate fracture classification virtual surgery system was established for each type of fractures. Doctor can make the corresponding decisions about surgical program and choice of internal fixation according to the specific type of fracture as well as repeated operational practice in the virtual system.Results1.3D digital models of common fracture classification systems were established. The 3D digital model has the characteristics of three-dimensional, intuitive, realistic and dynamic. The digital model can be magnified and reduced arbitrarily and turned transparent. The fracture patterns can be observed from optional direction and angle. Another main distinguishing feature was different fracture fragments can be assigned different colors in the digital model so that fracture patterns can be distinguished more easily. Screen-captures of fracture model were saved from multiple sides. The screen-captures were arranged and printed in order to facilitate the comparison with the traditional plane fracture atlas. Fracture patterns also can be exported as video mode which can rotate 360°automatically and be watched repeated. Compared with the traditional 2D schematic diagram,3D digital model has many features and advantages.2.3D digital fracture classification model has the characteristics of realistic shape and strong stereo feeling. The digital model can be imported into the virtual surgery system and manipulated through the force feedback device PHANTOM. The digital model was able to meet the requirements of virtual surgery systems for fracture classifications.3D digital model of surgical instruments and internal fixation devices has the characteristics of realistic shape and strong stereo feeling. Color and size of the virtual instruments were consistent with the real devices. The digital model of surgical instruments and internal fixation devices can be imported into the virtual surgery system and manipulated through the force feedback device PHANTOM. The model was able to meet the requirements of virtual surgery systems for fracture classifications.3. Virtual surgery systems of fracture classifications were established. Hardware of the system includes interactive devices with the force feedback function developed from the SensAble Technologies corporations, PHANTOM Desktop system with tactile feedback,1.6 MHz computer and display device. Utilizing the software GHOST of FreeForm Modeling System, softwares of virtual cutting, fracture reduction and fixation were developed. Using the force feedback device PHANTOM, doctor can manipulate virtual surgical instruments and fracture classification model to simulate fracture reduction and internal fixation. The virtual surgical environment has a strong sense of reality, immersion and telepresence as well as good interaction and force feedback function. The user can simulate surgical actions such as assembly of surgical instruments, drilling, implantation of screw, reduction of fracture, bone grafting, fracture fixation, etc. The user can get a certain degree of feeling similar to the actual operation and a force feedback feeling. The digital model of this system can be magnified, reduced and rotated arbitrarily in order to observe the anatomical structure of interest. The whole or part of digital model can be turned transparent which was conducive to observe the spatial position and adjacent relationship of the fracture fragments or surgical instruments. This virtual surgery system has the function of separate display and combined display which facilitated the assembly of surgical instruments and the completion of complex operations. With the "undo" function, the user can correct errors whenever necessary and return to the previous step or start again. The force feedback functions allowed the user feel the force of the virtual surgical environment and adjust the surgical operation.4. For different types of fracture, treatment is also different even for the same part of the bone. For example, Schatzker classification system of tibial plateau fracture includes six types. Each type had its own characteristics result that the differences of surgical method and choice of internal fixation. A separate fracture classification virtual surgery system had been established for each type of Schatzker classification system. The user can make the corresponding decisions about surgical method and choice of internal fixation according to the specific type of tibial plateau fracture as well as repeated operational practice in the virtual surgery system. Through the practice, the user can not only increase the operative proficiency, but also gradually understand and master the fracture therapeutic principles about surgical program and choice of internal fixation.Conclusions1.3D digital models of fracture classification systems were established using software Mimics. The fracture model has the characteristics of three-dimensional, intuitive, realistic and dynamic. Different fracture fragments can be assigned different colors in the digital model so that fracture patterns can be distinguished more easily. Doctor can interact with the digital model on his own computer. The digital model can be magnified and reduced arbitrarily and turned transparent. The fracture patterns can be observed from optional direction and angle. Fracture model also can be exported as video mode which can rotate 360 "automatically and be watched repeated.2.3D digital models of fracture classification systems are helpful for determining the fracture type. Compared with the traditional 2D schematic diagram, 3D digital model has many advantages and may be an important reference tool in classifying fractures. Establishment of fracture classification model database is an important content as well as a crucial basis of digital orthopaedic surgery.3D digital model is close to the real anatomy that is beneficial to understand the fracture type and arouse students’interest in learning. Therefore, the digital model is a novel and useful tool for medical teaching and orthopaedic clinic work.3.3D digital models of surgical instruments and internal fixation devices were established using software UG. The model has the characteristics of realistic shape and strong stereo feeling. Color and size of the virtual instruments were consistent with the real devices.3D digital models of surgical instruments and internal fixation devices can be imported into the virtual surgery system and manipulated through the force feedback device PHANTOM. The model can meet requirements of virtual surgery systems for fracture classifications.4. The virtual surgical environment has a strong sense of reality, immersion and telepresence in the FreeForm Modeling System. The virtual surgery system provides a new platform for orthopaedic surgical training. Softwares of virtual cut and virtual fracture reduction and internal fixation were developed by GHOST SDK. The system also has a good interaction and force feedback function. The user can optional manipulate virtual surgical instruments and internal fixation devices in the virtual surgery system and can simulate surgical actions such as assembly of surgical instruments, drilling, implantation of screw, reduction of fracture, bone grafting, fracture fixation, etc. The user can get a certain degree of feeling similar to the actual operation and a force feedback feeling. The user can perceive the force feedback through the force feedback device PHANTOM in the virtual surgical environment. The force feedback function is helpful for the user to adjust the surgical operation. Meanwhile, the force feedback function can make the virtual surgery more realistic.5. A separate fracture classification virtual surgery system was established for each type of Schatzker classification system. The user can determine the surgical method and choice of internal fixation based on the specific type of tibial plateau fracture. The virtual surgery system allows the user practice operation repeatedly. Through this practice, the user can not only increase the operative proficiency, but also gradually understand and master the fracture therapeutic principles about surgical program and choice of internal fixation for Schatzker classification system of tibial plateau fracture. Therefore, the virtual surgery systems of fracture classifications make the virtual surgery training more normalized, programmed and standardized. In addition, the virtual surgery system can serve as a new tool for preoperative planning and doctor-patient communication. |
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