| Objective To investigate the parameters of sacroiliac-through screws in the treatment of sacroiliac joint injury.Methods From January 2015 to January 2017,55 cases of adult images were examined by pelvic CT scan in our hospital imaging research center,To analyze the patient's imaging data by Mimics software,and the position,safety diameter and length of the screws were determined for the safe operation of the S1 and S2 sacroiliac pedicle screws.Simultaneously analyze the entry points of sacroiliac-through screws,safety diameter and length of the screw at S1 and S2.Results In this study,55 cases of complete images were selected,including 27 males and 28 females.Among them,48 cases were chosen for the screw fixation at S1 which accounting for 87.27%,38 patients were suited to fixation at S2 which accounting for 69.09%.As the results showed,at the left side of S1 sacroiliac through screw,the length of the A line was(95.41 ± 7.31)mm,the P line was(61.08 ± 5.06)mm,the angle of a was(88.83 ± 1.29)°,the angle of ? was(1.12 ± 0.03)°,? angle is(0.13 ± 0.01)°.Respectively,on the right side of the measured A line,P line,? angle,? angle and y angle were(97.32 ± 8.02)mm,(63.13 ± 5.39),mm(89.02 ± 1.03)°,(1.32 ± 0.07)° and(0.16 ± 0.02)°.There was no significant difference between the two groups(P>0.05).The results showed that the length of A line at S2 was(90.31 ±7.46)mm,the P line was(59.37 ± 4.32)mm,the angle of a was(87.98 ± 1.41)°,the angle of ? was(1.16 ± 0.04)°,? angle was(0.16 ± 0.01)0.Respectively,on the right side of the measured A line,P line,? angle,? angle and ? angle were(92.74±7.88)mm?(58.61±4.91)mm?(88.42±1.37)°?(1.27±0.05)° and(0.13±0.01)°.There was no significant difference between the two groups(P>0.05).The study shows that the left radius of the S1 sacroiliac-through screw was(5.65 ± 0.65)mm and the right radius was(5.87 ± 0.71)mm.The radius of the S2 sacroiliac-through screw was(4.61± 0.39)mm and the right radius was(4.56 ± 0.32)mm.The difference was statistically significant(P<0.05).The length of S1 sacroiliac-through screw was(168.32 ± 7.42)mm and the length of S2 sacroiliac-through screw was(143.43 ± 5.71)mm.The difference was statistically significant(P<0.05).Conclusion The 3D model of pelvic CT images was established by Mimics software.Through different angles of motion,image segmentation and reconstruction,doctors could predict and measure the safety channel of sacroiliac-through screws.For the existence of lumbosacral vertebral dysplasia at some sacroiliac joint injury patients,surgeons should be carefully selected the sacroiliac-through screws fixation and the preoperative application of Mimics software was suggested.The radius and length of sacroiliac-through screw at S1 screw were longer,which could offer impressive effect.Objective To analyze the mechanical properties of sacroiliac-through screw in sacroiliac joint injury by using finite element software.Methods To reconstruct pelvic three-dimensional model by Mimics 16.0 software,and simulate the model of pelvic sacroiliac joint injury,then to analyze the internal fixation model of sacroiliac screw by finite element analysis.As a result,analyzing the mechanical properties of sacroiliac-through screw and common sacroiliac screw in unilateral and bilateral disruption of sacroiliac joint.Results Applying 600N gravity force on the surface of the sacral endplate,the trajectory of stress conduction at a normal pelvic finite element model was start from the sacral endplate,and downward from both sides of the surface of the sacral wing to the sacroiliac joint and the pelvic arcuate line and greater sciatic notch,which reach the bilateral top of acetabular.The sacral superior endplate suffer the maximum stress,followed by the sacroiliac joint and the acetabular position,while the pubic branch and pubic symphysis of the pelvic model suffer the least energy.The vertical stress of 600N was applied on the surface of the sacral endplate,the stress distribution of the pelvic injury model was transmitted to both sides of the injured sacroiliac joint,which was less symmetrical than that of the normal pelvic model.The maximal stress was located on the injured sacroiliac joint.The sacrum had a downward and forward movement trend while iliac bone rotation at the injury model of pelvic.The lengthened sacroiliac screw fixation model:the sacral superior endplate on the vertical displacement of 0.563mm.The bilateral common sacroiliac screw fixation model:the vertical displacement of the sacral superior endplate was 0.618mm.There was no statistically significant difference between the two groups.The lengthened sacroiliac screw fixation model:the vertical displacement of the sacral superior endplate was 0.494mm,unilateral common sacroiliac screw fixation model:the sacral superior endplate vertical displacement of 0.587mm.There was significant difference between the two groups(P<0.05),Conclusion For both sides of the sacroiliac joint disruption,the sacroiliac-through screw and the common screw fixation both have good stability.For unilateral sacroiliac joint disruption,the sacroiliac-through screws could provide more stability.Objective According to the previous study of sacroiliac-through screw to guide its application in the sacroiliac joint dislocation.Methods Ten specimen models of sacroiliac joint dislocation were made by biomechanical testing machine,the specimens were scanned by CT and the scanning data were imput into Mimics software.The sacroiliac-through screw was subjected to individualized measurement,and the sacroiliac-through screw was implanted according to the measurement results.Results The data were analyzed using Mimcis software,of which only 8 models were implanted with sacroiliac-through screw.2 cases could not be safely implanted screws because of the lumbosacral vertebral dysplasia.Sacroiliac-through screws were successfully implanted from right to left at S1 in 8 models,all screws throughout the bilateral sacroiliac joint and sacral vertebral body,and completely following along the bone pathway.Conclusion The spiral CT scan combined with Mimics software was used to simulate sacroiliac-through screw fixation,which could accurately measure the parameters of the sacroiliac-through screw.At the same time,it was of great significance to select the entry point,angle and length of the screw. |
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