| Part IThe measurement of proximal femoral morphological of crowe IV adult DDH prosthesisObjective: To study thethe morphology of proximal femoral medullary cavity, femoral head shape and characteristics of high hip dislocations for Crowe type IVdevelopmental dysplasia of the hip(DDH) in adults,and confirmed the special anatomic change of Crowe IV type DDH. Providing the references for dealing with the femurin total hip arthroplasty in adult DDH, and provides the reference for the designsof 3D printing personalized artificial femoral prosthesis for Crowe IV type DDH in adults.Methods: Randomly selectedthe X-ray datasof anteroposterior and lateral radiographs of proximal femurof 49 cases(58 hips) and 3D CT image datas of 17 cases(17 hips)(DICOM format) of Crowe IV type DDH in adults between 2004 June to 2014 December indepartment of orthopedics of First Hospital Affiliated to Suzhou University.Measured parameters ofdiameter in each case of proximal femoral medullary cavity with Osirix 5.85 software, includedinner diameters of medullary cavity every 1cm from 2cm above the most prominent point of the lesser trochanterto 10 cm below which, and inner diameter of isthmus, thickness of spondylolysis corticalinner and outer side of the isthmus, height of isthmus, dislocated distance of femoral head.Morphological parameters: including the canal flare indexof proximal femoral medullary cavity(CFI), metaphyseal canal flare index(MCFI)and the improved MCFI index( MCFI 2), distal canal flare index(DCFI) and neck shaft angle and the anteversion, femoral morphology. Statistical analysis was performed using Excel2007 and SPSS16.0,comparative studied the anatomic parameters of theproximal femoral medullary cavity of the normalpopulationreported by domestic and foreign scholars, analysisedthe characteristics and relationship of anatomic parameters of femoral medullary cavity in Crowe IV type DDH patients, and analysis thespecial anatomical change of Crowe IV type of proximal femur.Results: 1. Measurement of 49 patients(58 hips) in patients with Crowe IV type DDH in adults, there were 7 males(8 hips), 42 female patients(50 hips); male patients aged from 19 to 80 years, average 47.26 years old; female patients aged from 18 to 73 years old, average 37.01 years old. The incidence of DDH in female was higher than male, the age of onset was younger compared with primary osteoarthritis of the hip.2. Measured the diameterparameters of proximal femoral intramedullary of each side hip, the morphology of medullary cavity of femur of Crowe IV type DDH was obviously narrow and straightthan the normal population,inner diameter became smaller obviously, there was significant difference(P<0.01); the average distance between the femoral head dislocation was 6.09 ± 1.04cm; 8 hips(13.8%)related with femoral head and neck disappear completely and invisible; 11 hips(19%) relatedwith femoral head atrophy and deformation, femoral neck disappeared; the rest had different degree of deformation of the femoral head. The mean neck-shaft angle increased as 132.3°±9.06°(90.5-158.1°).3, Femoral neck anteversion of 17 cases(17 hips)were measured by use of three dimensional CT(17 hips) of Crowe IV type DDH in adults, a hip femoral neck disappeared completely and invisible, and could not measur the anteversion. There are 3 hips(17.6%) which femoral neck anteversionreversed, 13 hips(76.5%) anteversion, the average femoral neck anteversion angle significantly increases: 37±18.2 degrees, more larger compared to the normal population, there was significant difference(P<0.01).4, According to Noble classification, the mean CFI value is 3.50±0.42 of 58 hips with Crowe IV type DDH in this group, more smaller than the normal population, there was significant difference(P<0.01). The chimney type cavity(CFI < 3) accounted for 51.7%, normal medullary cavity(3 < CFI < 4.7) accounted for 48.8%, funnel type cavity(CFI > 4.7) accounted for 3.5%. Chimney type cavity ratio was significantly higher than that of other scholars measured innormal type of femoral cavity.Conclusion: 1, The anatomic morphology and size was variation of proximal femoral of Crowe IV type DDH in adults, there was considerable anatomical deformities in proximal femur, and have obvious difference compaired to normal peoplein the proximalfemoral morphology, so it is necessary to design individualized femoral prosthesis conforms to characteristics of proximal femoral medullary cavity in patients with DDH.2, The morphologyof proximal femoral is fine and straight of Crowe IV type DDH in adults, chimney type possessedhigh proportion,but different fromthe chimney typeof elderly,which was caused by osteoporosis and bone loss.3, The author improved metaphyseal canal flare index(MCFI 2) has guiding significance on thedesign of individualized femoral prosthesis which mainly fixed through metaphyseal.Part IIComputer Assisted Design of Individualized Femoral Prosthesis and(EBM RP) Metal 3D printObjective:Confrontdedthe severe deformity of proximal femoral medullary cavity caused by DDH and other diseases, and encountered the difficulty during THA with traditional standard femoral component, designed a personalized artificial femoral prothesis through computer aided design technologyand produced samples by electron beam melting(EBM, RP)3D printing technology, applied in a series of subsequent experimental study.Methods: Throughscanning on a cadaver femur with thin slice of 0.625 mmthick layer by using 64 slice spiral CT, obtained a tomographic image data; opened and saved as JPG format by using CDViewer tools,conversedall JPG format into BMP format batch by using the ACDSee tool; imported into Mimics15.0 and editedfor pretreatment, completed three dimensional reconstruction of femur, generated standard STL file format; based on the 3D inner contourof femoral cavity, designed 3D model of individualized prosthesis through UG 8.0 software;Importedstl. format files of individualized artificial femoral prosthesis into the main computer program of EBM RP 3D metal printer, adjusting parameters of pore diameter and porosity, printed out personalized sleeve; polishedthe inner surface of conicalcavity of sleeve, and assembled with the stem component of SR standard modular prothesis. completed the design and manufacturing of individualized femoral prothesis.Results:①CT scanning of cadaveric femur obtained clearandcontinuous tomographicimage datas, and successfully completed the conversion of images; ②importedthe image files into Mimics15.0, completedthe initialization and spatial location settings, edited pretreatment, removed noise, adjusted the threshold, region growing, determined the outline line of femur byautomatically extraction combined to manual extraction, 3D reconstruction to obtain the 3D model file of standard STL format of the proximal femur. ③Importedthe 3D graphics file in STL format of femoral generated by Mimics15.0 into UG 8.0, extractedthe 3D model of femoral cavity surface,marked 3.5-5cm metaphyseal inner contour as the outer surface of the personalized sleeves; and placed anappropriate size of standard SR prosthetic componentin the central of medullary cavity, formedinternalconical cavity in personalized sleeves; analog synthesisof personalized sleeve andstandardization prosthesiscomponent, placedthe modular prosthesis into proximal femoral medullary cavity and obtained simulatedeffect of THA. ④Obtained the personalized three-dimensional model of metaphysis sleeve afterappropriate smoothing and optimization processing of the outer surface. ⑤ Produced the personalized titanium alloy metaphyseal sleeve by using electron beam melting(EBM RP) metal 3D printer,after assemblingwith standard SR stem component, finished the product process of manufacturing of individualized femoral prosthesis.Conclusion:①Based thespiral CT images with thin layer scanning of femur, through the image transformation and related softwaresprocessing, satisfactory for 3D solid model of femur internal and external contour can obtainedby using the method of 3D reverse;②A good personalized femoral prosthesis matching the metaphyseal satifactory could be desigedof through the professional CAD technology on the basis of 3D model. It was possible to printpersonalized modulus titanium alloy femoral prosthesis with complexthree-dimensional, microporous in surface and low elasticity by using the latest(EBM RP) electron beam melting metal 3D printer.the technology with advantages of convenient, fast, accurate and printing prosthesis with individualization, perfect matching the metaphyseal cavity, and had wide application foreground.Part III EBM 3D metal printing of personalized femoral prosthesis and comparative analysis to the other four types cementless prosthesis with three dimensional finite element(FEA)Objective:Comparative analysised of EBM 3D metal printing personalized femoral prosthesis and the other four types cementless prosthesis(SR modular prosthesis, rectangular, cylindrical, taperedprosthesis), studied the biomechanical characteristics of personalized femoral prothesis so as to improve the design of which, played well basics for follow-up study.Method: Selectedthe 3D STL. files of personalized femoral prosthesis previously studied and the 3D STL. files of SR modular prosthesis( 14 D cuff, 2#, provided by AIkang Yicheng companies), selected the three kinds of common femoral stems with differentmorphology(cylindrical,rectangle, tapered) according to the the suitable size of femoral medullary cavity previously researched, scaned the three kinds femoral stems with Daheng 3D laser scanner, exported3 D stl. files to UG 8.0 softwareand reconsted three-dimensional model, repair bad point, got the required 3D stl. format files and export to Ansys10.0 software, prosthesisd finite element mesh of digital modeles of 5 femoral stems, resected femoral head, necksimulatively and implanted into the digitized femoral medullary cavity in accordance with the standard operative requirements respectively. After assigned materials ofthe femur and prosthesis materials, simulated biped still standing andslow walking staterespectively, a simulation experiment was carried out of five kinds of prosthesis by using Ansys10.0 software, compared four biomechanical characteristics as stress distribution, interface stress, initial fretting, stress shielding ofthe five kinds of femoral prosthesis.Results: 1, When standing still with double foot, mean stress of individualized femoral prosthesis was only slightly higher than the cylindrical prosthesis, positive stress was only slightly higher than the taper prosthesis, shear stress was lower than the other prosthesis; When inlow-speed walking condition, mean stress of individualized femoral prosthesis wasonly slightly higher than the cylindrical prosthesis; the positive stress lower than SR modular prosthesis and higher than the other three types of common prosthesis. The maximum stress point was located at the corner of the prosthesis neck; the shear stresswas lower than SR andrectangular prosthesis(25.78%, 62.50%), higherthan cylindrical and tapered prosthesis(35.74%, 15.82%).2, When standing still with double foot, horizontal micro motion of individualized femoral prosthesis was higher than the other femoral stems, the maximum value was26.4um, in the micro range of bone ingrowth; the vertical micro motion was lower than the other four prosthesis. When inlow-speed walking condition, the horizontal micro motion of individualized femoral prosthesis was higher than the other femoral stems, the maximum value was398um; the vertical micro motion was slightly lower than cylindrical prosthesis and slightly higher than SR, rectangular,and tapered prosthesis(16.10%, 23.67%, 1.54%).3, When standing still with double foot and walking slowly, personalized sleeve was lower than SR standard sleeve inmean stress, positive stressand shear stress; the horizontal micro motion was slightly bigger, the maximum value of which was 26.4umand172 um repectively, in the micro critical range of bone ingrowth.When standing still with double foot personalized sleeve was lower than SR standard sleeve invertical micro motion about(50%), the maximum value was 0.407mm; When inlow-speed walking condition, vertical micro motion was slightly higher than SR standard sleeve(11.68%), the maximum value was 1.701 mm.4, When standing still with double foot,the rate of proximal stress shielding of individualized femoral prosthesis was minimum, lower than the SR, rectangular, cylindrical and tapered prosthesis about 56.21%, 41.88%, 23.92% and 17.98%respectively. When inlow-speed walking condition, the rate of proximal stress shielding of individualized femoral prosthesis was minimum, lower than the SR, rectangular, cylindrical and tapered prosthesis about 56.84%, 31.10%, 20.45% and 16.69%respectively.Conclusion: 1, EBM 3D metal printing personalized femoral prosthesishad better biomechanical properties than SR modular prosthesis in stress distribution, interface stress and stress shielding.2, in the normal femoral medullary cavity, The individualized femoral prosthesis had lower stress shielding than ordinary prosthesis, the initial horizontal micro motion was higher than common prosthesis, but the micro motion was in therange of bone ingrowth; 3, The 3D metal printing personalized femoral prosthesis was more suitable for the patients withabmormal proximal femoral medullary cavity and anteversion for its personalized design and adjustable neck anteversion. Integrative individualized femoralprosthesis with 3D metal printing was the trend of artifical prosthesis in future. |
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