| Part I:Digital anatomy on the parameters of LC-? screw channels and insertion of a single LC-? screwObjectives:To simulate the process of intraoperative percutaneous insertion of LC-?screw,and analyze and measure the planned ideal LC-? screw insertion channel through digital medical software;meanwhile.This study measured the anatomical parameters of a single LC-? screw insertion,in order to provide an accurate and comprehensive applied anatomy basis for the percutaneous insertion of a single LC-? screw,thereby improving the safety and accuracy of the screw insertion.Methods:From February 2017 to February 2019,a total of 43 adult patients(21 males and 22 females)who underwent complete pelvic CT examinations at the Radiology Department of our hospital were randomly enrolled;the digital pelvic three-dimensional(3D)model was reconstructed using Mimics 21.0 software;further,in the 3-Matic13.0 software,the "cross-section method" was used to plan an ideal LC-? screw channel.Measurements were conducted regarding the maximum length DAP of the LC-? screw that the channel contained,the maximum diameter(Dmax),the distance from the first stenosis to the posterior superior iliac spine(D1),the distance from the second stenosis to the posterior superior iliac spine(D2),outer diameter of the first stenosis(OW1),inner diameter of the first stenosis(IW1),outer diameter of the second stenosis(OW2),and inner diameter of the second stenosis(IW2).At the same time,the horizontal distance of the central axis of the LC-? screw from the anterior superior iliac spine at anterior iliaccross point(Dh1)and its vertical distance(Dv1),the horizontal distance of the central axis of the LC-? screw from the anterior superior iliac spine at the cross point of skins in anterior iliac regions and its vertical distance(Dv2)were measured;the included angles between the central axis of the LC-? screw and the coronal,sagittal,and horizontal planes,??,??,??,were measured.Results:Of the 43 patients,the whole LC-? screw channel could be planned in 42(97.7%),and 1 female failed,because the outer and inner diameters ofcross-section ilia of LC-? screw channel were small,and the curvature of shallow arcuate structure in 3 areas was big,so the channel and screw insertion parameters were not measured.Of the 21 female patients in whom the whole LC-? screw channel could be planned,5(23.8%)had a maximum diameter of less than 6.5 mm for LC-? screws inserted.Except for channel parameters D1 and OW2,there were statistical differences in other parameters between males and females.The maximum length of LC-? screw was(147.68±7.29)mm in males and(136.41±9.83)mm in females,and the difference was statistically significant(P<0.001);the maximum diameter of LC-? screw was(9.16±1,34)mm in males and(7.04± 1.63)mm in females,and the difference was statistically significant(P<0.001).There was no statistical difference in the LC-? screw insertion parameters between males and females except for ??.Based on the digital pelvic 3D model,the bony insertion point of the LC-? screw at anterior iliac regions was located in the posterior area of anterior inferior iliac spine.The included angle between LC-? screw and coronal plane was 48.06°for males and 45.10° for females;the included angle between LC-? screw and sagittal plane was 27.14° for males and 25.60° for females.Conclusion:Digital medicine was an ideal tool for studying the anatomical structure of LC-? screw bone channel.The LC-? screw channel could be planned by digital medical software,and by measuring the screw channel and insertion parameters,it could provide a comprehensive applied anatomy basis for the insertion of LC-? screw in a fast,safe and accurate manner.Part ?:Development of a percutaneously inserted digital template of LC-? screwObjectives:This study designed a percutaneously inserted digital template of LC-?screw,which can be applied individually for safe,rapid and accurate percutaneous insertion of LC-? screwsMethods:In December 2018,a 36-year-old male patient undergoing a complete pelvic CT scan at the Radiology Department of Jiangyin People's Hospital was selected According to the methods described in the first part of the subject Digital Anatomy Study on the Parameters of LC-? Screw Channels and Insertion of a Single LC-? Screw,the LC-? screw channel at the left pelvis was planned,and LC-? screw insertion was simulated for subsequent use.In the 3-Maticl3.0 software,skins around the insertion point of the LC-? screw were selected to make a digital skin model.According to the skin model,the digital template material fitting it was made,and finally the design of percutaneously inserted digital template of LC-? screw was completedResults:The design of percutaneously inserted digital template of LC-? screw was completed,which consisted of a skin-fitted panel,an LC-? screw guide tube,and two fixed needle guide tubes.The skin-fitting panel was designed according to the skin at the anterior superior iliac spine,and can be well adhered to the above area.The LC-? screw guide tube allowed the insertion of a 2.5-mm guide needle.For the two fixed needle guide tubes,one was placed on the anterior superior iliac spine,and the otherwas placed on the iliac tuberosity,allowing the insertion of a 2.5-mm fixed needleConclusion:In this study,the percutaneously inserted digital template of LC-? screw designed by digital medical software had a certain scientificity,and the design methods could be individually applied according to the CT data of different patientsPart ?:Development of a percutaneously inserted adjustable guiding device of LC-? screw based on digital medical measurementObjectives:To design a percutaneously inserted adjustable guiding device of LC-?screw based on digital medical measurementMethods:According to the methods described in the first part of the subject Digital Anatomy Study on the Parameters of LC-? Screw Channels and Insertion of a Single LC-?Screw,the positional relationship(horizontal and vertical distances)between skin needle insertion point of LC-? screw and bone landmark(anterior superior iliac spine)of the body surface,and the included angles between the needle insertion direction of the LC-? screw and the sagittal and coronal planes were obtained.First,the location of the anterior superior iliac spine was determined,and then according to the data measured in the digital medical software(Mimics 21.0,3-Matic13.0),the needle insertion point and direction of LC-? screw were found through the designed percutaneously inserted adjustable guiding device of LC-? screw;a 2.5-mm guide needle was inserted along the guide sleeve.Fluoroscopy was performed to determine the correct position of the guide needle,the LC-?screw was screwed along the guide needle.Results:A percutaneously inserted adjustable guiding device of LC-? screw based on digital medical measurement was designed,including a base,a locator and an angle guiding device.The locator was used to locate the needle insertion point of the LC-? screw in the body surface,and the angle guiding device was used to adjust the direction of needle insertion.Conclusion:According to the insertion parameters of the LC-? screw obtained by digital medical measurement,the LC-? screw could be percutaneously inserted by the guiding device in a safe,rapid,and accurate manner,thereby shortening the radiation exposure and operation time,and reducing the surgical trauma.Part ?:Biomechanical study of minimally invasive fixation of pelvic crescent fracture with LC-? screw----finite element analysisObjectives:To compare the stability and biomechanical compatibility for the fixation of Day? pelvic crescent fracture with two LC-? screws vs two plates by finite element analysis;compare the stability and biomechanical compatibility for the fixation of Day?pelvic crescent fracture with two LC-? screws alone vs two LC-? screws combined with a sacroiliac screw.Methods:Pelvic CT data of one volunteer were selected;by digital medical software(Mimics 21.0,3-Matic 13.0),Day? and Day? fractures were planned according to the Day classification of pelvic crescent fractures,and positions of the two LC-? screws and one sacroiliac screw for the fracture fixation were planned;finite element analysis software(Geomagic Studio12.0,Pro/Engineer5.0,Hypermesh 12.0,and ANSYS13.0)was used to construct five three-dimensional finite element analysis models of pelvis,including a physiological model(normal pelvis),two Day? fracture fixation models,and two Day?fracture fixation models;four load modes of upright,flexion and extension,lateral bending,and rotation were stimulated;displacement and stress distribution of the five models were analyzed.Results:For the Day? pelvic crescent fracture,there was little difference in displacements of the intact pelvis,Day?-screw,and Day?-plate models in all load modes;in the load mode of anteflexion,displacements of the intact pelvis,Day?-screw,and Day?-plate models were the largest,which was 0.57mm,0.76mm,and 0.68mm,respectively;the stress values of the Day?-plate and Day?-screw test models in different load modes were significantly increased:the stress values were increased by 320%in the upright load mode,134%in the anteflexion mode,211%in the backward extension mode,339%in the left lateral bending mode,208%in the rightlateral bending mode,321%in the left rotation mode,and 284%in the right rotation mode.For the Day? fracture,there was little difference in displacements of the intact pelvis,Day?-screw,and Day?-sacroiliac screw models in all load modes;in the load mode of anteflexion,displacements of the intact pelvis,Day?-screw,and Day?-sacroiliac screw model were the largest,which was 0.57mm,0.82mm,and 0.64mm,respectively;the stress values of the Day?-sacroiliac screw and Day?-screw test models were increased by 133%in the upright load mode,96%in the anteflexion mode,33%in the backward extension mode,89%in the left lateral bending mode,24%in the right lateral bending mode,113%in the left rotation mode,and 97%in the right rotation mode.Conclusion:For the Day? pelvic crescent fracture,two LC-? screws and two plates could offer good pelvic stability,but the plate placed at the sacroiliac joint had obvious stress concentration,and risks of fatigue fracture of the plate and screw loosening were greater than those of the LC-? screw.In the case of successful closed reduction,two LC-?screws were preferred for internal fixation.For the Day? fracture,two LC-? screws and two LC-? screws plus a sacroiliac screw could maintain good pelvic stability,and the addition of a sacroiliac screw had more significant stress distribution than LC-? screw alone;furthermore,the insertion technique of sacroiliac screw had high requirements,and increased surgical risk;therefore,under successful closed reduction,two LC-? screws were enough for the fixation. |
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