| OBJECTIVE: Sacroiliac joint screw for the treatment of sacroiliac joint dislocation has the advantages of simple operation,less bleeding and less injury.By dividing the midsagittal section of the sacral vertebra into nine sections,this paper discusses the safety and stability of the sacral passage screw in different areas when the screw is placed in the treatment of sacroiliac joint injury,improves the meaning of the safe passage of the sacral passage screw in the sacroiliac joint,and further guides the clinical selection of screw placement by computer navigation technology.METHODS: 1 Definition and update of the safety channel of sacral screw,to discuss the safety of screw placement.The original pelvic CT files of 56 adult men and women in normal China were collected and imported into the Mimics image software processing station for data collation and analysis.Determine the spatial coordinate axis of the pelvic stereo image in the software,adjust the image to obtain the central position at the narrowest point of the sacral pedicle,and obtain the classic safe channel of the osseous channel.The range of the intervertebral foramina of the sacral screw,the classic safe channel of the pedicle screw,the range of the maximum safe channel,the direction and Angle of the insertion of the sacral screw,etc.2 A three-dimensional finite element model of the pelvis with complete bone structure was constructed to investigate the mechanical stability of the sacral screw placement.By constructing the pelvic injury model of sacroiliac joint injury with hollow screw placement,the stress cloud diagram and the main stress value/displacement cloud diagram trend of the tip of the sacro1 screw under the same load in the nine sections of the sagittal section of the sacro1 vertebral body were analyzed,and the optimal mechanical region of the sacro1 vertebral body was confirmed.3 By comparing the clinical operation,application advantages and postoperative efficacy of the commonly used C-arm two-dimensional scanning fluoroscopy technique(fluoroscopy group)and the emerging O-arm threedimensional scanning computer-aided navigation technique(navigation group),the development prospects of the two techniques were analyzed.RESULTS: 1 the ideal length of the sacral pedicle screw in the classic safe passage is(83.32±1.02)mm;the maximum safe channel screw range is(92.93±4.98)mm.The area of projection of the classic safe passage on the midsagittal plane of the sacral vertebral body was 704.73±3.21mm2,and the area of projection on the left iliac external cortex was 704.73±3.21mm2.The projected area of the maximum safe passage on the midsagittal plane of the sacral vertebral body was 934.24±3.21mm2,and the projected area on the left iliac external cortex was 1334.45±3.52mm2.The maximum safe channel range is significantly larger than the classical safe channel range.2 The stress distribution pattern and screw stress concentration position of the finite element model of pelvis in this study are consistent with the previous research conclusions,and the model is proved to be effective.Under the load of500 N,the stress cloud diagram shows that the maximum Von Mises principal stress value of the sacral screw in the N1 to N9 region presents a linear decreasing trend,which confirms that the bone mass in the upper region of the sacral vertebra is denser than that in the lower region.3 Majeed score of postoperative function in the navigation group: 34 cases were excellent,10 cases were good,and 2 cases were acceptable,with an excellent and good rate of 95.6%.Postoperative radiographs and CT reexamination showed that all the patients were satisfied with fracture reduction.In the perspective group,the score was good in 3 cases,and good in 1 case,with an excellent and good rate of 92.5%.However,the operation time and number of fluoroscopy were significantly less in the navigation group.CONCLUSION: 1 Sacroiliac screw in the treatment of sacroiliac joint dislocation has the advantages of simple operation,accurate positioning,less bleeding and less injury.Under the condition of ensuring effective fixation strength,it is recommended to choose a single hollow screw with a diameter of6.5mm and a length of 70-80 mm for sacroiliac joint screw fixation.The Angle between the best direction of insertion of sacroiliac joint screw and the coronal plane of the sacral vertebra is about 30°,the Angle between the horizontal plane and the coronal plane of the sacral vertebra is 15°,and the Angle between the joint screw and the left iliac external plate is about 90°.2 Preoperative CT scan can provide a safe,rapid and accurate individualized surgical plan for patients with sacroiliac joint dislocation fixed by screw.3 In this study,a three-dimensional finite element model of the pelvis with complete bone structure was constructed to study the influence of boundary and contact conditions,with strong reducibility and reliable results.It is verified that the pull torque of the sacral screw is higher in the upper part of the sacrum than in the lower part.On the premise of safety,the tip of the screw should be as close to the upper endplate of the sacral vertebra as possible to avoid screw loosening and reduce the screw pulling rate.4 Intraoperative CT 3D scan significantly improved the accuracy of pelvic fracture channel screw placement.The surgeon can actively select the screw direction and screw length under direct vision.At the same time,computer-aided navigation technology can reduce occupational exposure to radiation,reduce blood loss,short operation time,stabilize fracture fixation,early functional exercise,fewer postoperative complications,and high patient satisfaction,which is one of the cutting-edge technologies and development directions of minimally invasive pelvic fracture surgery in the future. |
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