Establishment And Validation Of Three Dimensional Finite Element Model Of Wrist Joint

Objective: Using high resolution MR and the autopsy method to build the threedimensional finite element model of normal human bone and soft tissue,including wrist tendon,ligament and cartilage,and to verify its accuracy.Methods: Normal three-dimensional finite element model of human wrist joint: Select a male fresh frozen cadaver specimens,routine examination and wrist X-ray examination to determine the non wrist disorders,64 rows of high resolution spiral nuclear magnetic resonance machine produced by Germany Fhilips slice thickness setting machine 0.625 mm,scanning interval is 0.625 mm,the scanning area is at the lower end of the right forearm distal region,including ulnar and radial section,all under the wrist and metacarpal and phalangeal bone and soft tissue structure.The scanned data output in Dicom format,and imported into Mimics 10 software,adjust the threshold to select all bone tissue,and through regional growth,smooth surface treatment,complete reconstruction of wrist bone rough model.Adjust the threshold of MR data again,select each part of tendon,ligament and cartilage plate.Because of the soft tissue between the threshold is similar to that of MR image difficult to accurately distinguish the autopsy and method of MR image control,dissect the carpal ligament,and the cartilage,and compared with MR images,the various parts of tendon,ligament and articular disc to distinguish,segmentation,reconstruction,get wrist soft tissue rough model.All the data in Point Cloud format output,and import the Geomagic studio 10 software,followed by some stage,stage,polygon processing and surface division stage,the bones,tendons,ligaments and articular disc tissue rough model contour relaxation,encapsulation,smooth surface,construction process,part angle and surface the repair manual operation is required,more fine and meet the wrist bone anatomy model.The wrist bone tissue was used as the working coordinate system,and the direction and position of the soft tissues and bones were carefully adjusted according to the anatomical relationship between the tissues of the wrist.The model was imported into Ansys 12 software in IGS format,and then the 3D finite element model of wrist joint was obtained by defining the unit model,material properties and meshing.Amphiarthrosis intercarpal model used in cartilage link connection,large activity such as wrist joint,metacarpophalangeal joint is connected by each contact element.2,Verify the three-dimensional finite element model of wrist joint: Using Ansys 12 software to open the three-dimensional finite element model of the wrist joint,the proximal ulna and radius is set to a fixed point,axial pressure of 100 N in the metacarpal head,the contact stress distribution calculation under the pressure of radiocarpal joint surface pressure obtained by the mechanical study method and reported in the literature by comparing the accuracy of three-dimensional finite element model used in this experiment to verify the research methods of the reconstruction.Results: In this experiment,the three-dimensional finite element model of wrist joint was established by using MR image and autopsy.The model includes the ulnar and radial section(each 1),wrist(total 8),metacarpal(total 5)and the triangular fibrocartilage complex(articular disc,palmar and dorsal distal radioulnar ligament,joint capsule,ulnotriquetral ligament,extensor carpi ulnaris,radiolunate etc.)the radioscaphoid ligament,ligament structure.The model consists of 829345 nodes,42154 solid elements,and a contact unit of 739.In the axial pressure 100 N of the metacarpal head under the scaphoid bone conduction to the wrist joint contact stress is 5.3 Mpa,contact July radiocarpal joint bone conduction to the stress of 3 Mpa,the ratio of the two to 1.767,consistent pressure obtained by mechanical method and research reported in the literature,the rationality of three-dimensional the finite element model of the wrist joint thus it is proved that the experimental method of the.Conclusion: The three-dimensional finite element model of wrist joint construction method using MR image and autopsy combination,the precise anatomical structure,the corresponding relationship is reasonable,the operation is relatively simple and feasible experiment,and provides a new way for the construction of a threedimensional finite element model of the complex structure,but also provides research ideas new for biomechanical analysis of wrist.