| Objective: To assess effects and security of the insertion of sacroiliac screws by computer assisted thermoplastic elastomer film localization system.Methods:1 Materials and groups Test Group: In a simulated surgical setup 10 cannulated screws were placed into the sacroiliac screws of 10 pelvis under the guidance of the system. Control group: Ten cannulated screws were placed into the sacroiliac screws of 10 pelvis by traditional methods through the C-arm machine perspective.2 Experimental equipment 10 Adult males corpse specimens. Hot plastic membrane system. C arm perspective. Through the X-ray operating table. Locator. Hollow nails devices. Timer. Measuring . Marker pen.3 Operation steps:Test Group: The pelvic is placed prone body position in the bottom of the positioning system and put the thermoplastic elastomer film in 65℃tank, covered in the pelvis after staying the thermoplastic elastomer film soft. We should try to stick to surfaces of pelvis, and fix the thermoplastic elastomer film on the bottom. Marking this position with thermoplastic elastomer film after temperature drop to harden. Then the pelvis are put on CT examination table, and a planar is labeled consistent with a CT scan direction application 3d laser tracking in the pelvis. Three the different line points in the planar are choosed and used the lead point marker. The CT data is transmitted to treatment planning system , 3d image formaing in the treatment plan software. Doctor, which has experience of placing sacroiliac screws, choose the direction of the best nail way ,the injection depth, finally reaching the position of the sacrum and precise calculate the length of the screw in 3d image, then the virtual needle points are marked on the thermoplastic elastomer film. The virtual needle points are located. Then data is located to the thermoplastic elastomer film and marked by 3d laser tracking. To simulate the real operation process firstly, the pelvis are removed and put back again, after the thermoplastic elastomer film fixing. This process is called "reset". The reset rate is 90% by the thermoplastic elastomer film. After successful resetting, the ends of locator consistent the needles points and a virtual points are made on the thermoplastic elastomer film. 2.5 mm guide pin is scored through the robot design nail way,hole is used hollow drill enlarge and the 7.3 mm cancellous bone hollow nails is thread into, the guide needle is taken out. The pelvis is checked through visual, CR and CT, then the screws are removed.Control Group: Percutaneous sacroiliac screws operation are simulated. Before the operation, we understand the general form of pelvic by A-P position, the pelvic inlet and exit image. Standard prone body is located on the operation bed,vertebral S1 is determined by C arm X-ray machine. The points are select properly which are anterior of spina iliaca posterior inferior (24. 6±2. 9)mm ,and anodic greater sciatic notch (41. 8±3. 4) mm,Guide pin is scored and hole is used hollow drill to enlarge and the 7.3 mm cancellous are bone hollow nails thread into. The pelvis is checked through visual, CR and CT, then the screws are removed.We definite the screws whether or not break through the sacral canal, sacral foramen,S1 and pedicle of vertebral arch of S1.Results:1,Test Group,Putting a screw through Computer-assisted Thermoplastic Elastomer Film Localization System, We need average time which is 29.3 seconds(15.4-55.7秒) without fluoroscopy. Through the visual 10 screw hollow nails, all were not break out the bone cortex, frontal cortex, sacral nerve hole and spinal canal. All the screw position are content through the pelvic entrance and exit image of CR display, CT scans show 10 sacroiliac joints in safety zone screw.2.Control Group In the fluoroscopy of operation under control, the time that a screw was insert is the average fluoroscopy 29.8 times (19.0-43.0 times), average fluoroscopy for tired fetched seconds (12.0 30.0 seconds), average - operating time for 413.6 seconds (243.0-589.0 seconds). One screw of 10 sacroiliac joint screws wear out front cortex(10%) Conclusion: Through the experimental study we found the advantage of Computer-assisted Thermoplastic Elastomer Film Localization System is :①providing precise and accurate location of the space navigation path sacroiliac joint screws .②inserting a guide needle need a few seconds and saving the time of operation.③it can make patients and physicians to avoid the repeated X-ray exposure.④This method is truly minimally invasive and reduces haemorrhage , protects soft tissue and reduces postoperative infection.At present, the system is not consummate ,operation needs in CT room; the Problems of disinfection and operating environment is further to solve; System design need to optimize ,operation flow into need to benchmarking. |
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