| Objectives:A three-dimensional finite element model was established for ReganMorrey type II and type III fracture of the ulnar coronoid process fracture fixed with Kirschner wire,screw and anatomical bone plate.Three conditions of anti-pull-out,anti-horizontal displacement and anti-rotational displacement were simulated by computer software and finite element analysis was carried out to compare the stress of internal fixator of ulna coronoid process,the displacement change and stress distribution of fracture block.We aim to provide theoretical bases for the selection of internal fixation by exploring the biomechanical differences of three different internal fixation methods,and evaluating their stability in the treatment of ulnar coronoid process fracture.Methods: Elbow joint of a healthy young volunteer was scanned by the 128-slice spiral CT.The CT data were imported into Mimics 21.0 software to create an ulnar coronoid model,and materialize the ulnar coronoid model with Geomagic studio 2013 software.The ulnar coronoid model data were imported into Unigraphics NX 10.0 software to create models of the ulnar coronoid process Regan-Morrey type II and type III fracture,and to establish models of the kirschner wires,screws,and anatomical plate.The model datas were imported into Abaqus 6.14 software to create three internal fixation models of the ulnar coronoid Regan-Morrey type II and type III fractures,respectively,and to calculate three simulation conditions,it was the pull-out internal fixator simulation test,anti-horizontal displacement simulation test,and anti-rotation displacement simulation test.The loads of 0-100 N were gradually exerted to the three simulated conditions.The stress distribution of the internal fixation device and the fracture block,and the displacement change of the fracture block were recorded,the biomechanical characteristics of the three internal fixation methods for the two ulnar coronoid fractures were analyzed,and the displacement-load change curves and Mises stress cloud diagrams were plotted.Results:(1)Regan-Morrey Type II fracture: 1)Pull-out internal fixator simulation test:(1) The stress on the internal fixation device: screw group 148.14 MPa > anatomical plate group 120.43 MPa > kirschner wire group 51.32 MPa,compared with the kirschner wire group,the stress distribution in the screw and anatomical plate groups was slightly concentrated.(2)Thestress on the fracture block: anatomical plate group 80.22 MPa > screw group 56.56 MPa > kirschner wire group 52.14 MPa;(3)Themaximum displacement of the ulnar coronoid fracture block: kirschner wire group 0.4 mm > anatomical plate groups 0.1297 mm > screw group 0.0404 mm;(4)The stiffness of model system: screw group > anatomical plate group > Kirschner wire group.2)Anti-horizontal displacement simulation test:(1)The stress on the internal fixation device: screw group 209.41 MPa > kirschner wire group 190.62 MPa > anatomical plate group 130.45 MPa,the stress distribution of screw group and kirschner wire group was slightly concentrated compared with anatomical plate group;(2)The stress on the fracture block: anatomical plate group 83.00 MPa > kirschner wire group 71.32 MPa > screw group 29.96 MPa;(3)Themaximum displacement of the ulnar coronoid fracture block: 0.167 mm in the kirschner wire group > 0.127 mm in the screw group > 0.0985 mm in the anatomical plate group;(4)The stiffness of model system: anatomical plate group > screw group > kirschner wire group.3)Anti-rotation displacement simulation test:(1)The stress on the internal fixation device: screw group 281.38 MPa > anatomical plate group 272.57 MPa > kirschner wire group 223.64 MPa,the stress distribution in the screw group and anatomical plate group was slightly concentrated compared with the kirschner wire group;(2)Thestress on the fracture block: anatomical plate group 82.82 MPa > screw group 80.89 MPa >kirschner wire group 65.60 MPa;(3)Themaximum displacement of the ulnar coronoid fracture block: kirschner wire group 0.264 mm > screw group 0.210 mm > anatomical plate group 0.158 mm;(4) The stiffness of model system: anatomical plate group > screw group > kirschner wire group.(2)Regan-Morrey type III fracture: 1)Pull-out internal fixator simulation test:(1)The stress on the internal fixation device: Kirschner wire group 143.36 MPa > screw group 127.06 MPa > anatomical plate group 102.44 MPa.The stress distribution of Kirschner wire group was slightly concentrated compared with screw group and anatomical plate group;(2)Thestress on the fracture block: Kirschner wire group 83.21 MPa > anatomic plate group 82.20 MPa > screw group 67.78MPa;(3)Themaximum displacement of the ulnar coronoid fracture block: Kirschner wire group 0.2659 mm > anatomical plate group 0.1227 mm > screw group 0.0941mm;(4)The stiffness of model system: screw group > anatomical plate group > Kirschner wire group.2)Anti-horizontal displacement simulation test:(1)The stress on the internal fixation device: Kirschner wire group 214.93 MPa > screw group 138.47 MPa > anatomical plate group 100.94 MPa.Stress distribution of Kirschner wire model group was slightly concentrated compared with screw group and anatomical plate group;(2)Thestress on the fracture block: anatomical plate group 84.00 MPa > screw group 70.21 MPa > Kirschner wire group 27.30MPa;(3)Themaximum displacement of the ulnar coronoid fracture block: screw group 0.213 mm > Kirschner wire group 0.163 mm > anatomical plate grou 0.0926mm;(4) The stiffness of model system: anatomical plate group > screw group > Kirschner wire group.3)Anti-rotation displacement simulation test:(1)The stress on the internal fixation device: Kirschner wire group 313.36 MPa > anatomical plate group 249.02 MPa > screw group 227.28 MPa.The stress distribution of Kirschner wire group was slightly concentrated compared with screw group and anatomical plate group;(2)Thestress on the fracture block: anatomical plate group 82.60 MPa > screw group 71.53 MPa > Kirschner wire group 50.48MPa;(3)Themaximum displacement of the ulnar coronoid fracture block: screw group 0.306 mm > Kirschner wire group 0.305 mm > anatomical plate group 0.139mm;(4) The stiffness of model system: anatomical plate group > screw group > Kirschner wire group.Conclusions:(1)Fixing Regan-Morrey type II and III fractures of the ulna coronoid process with Kirschner wires,screws,and anatomical plate,the anti-pull-out property of the screws is more significant,and the anatomical plate have greater stability in the antihorizontal displacement and anti-horizontal displacement;(2)The anatomical plate has a good effect on maintaining the stability of fracture fragments in Regan-Morrey type Ⅱ and type Ⅲ fractures,especially for the type Ⅲ fracture;... |
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