Biomechanics Properties Of Intramedullary Fixation Of Clavicle Fracture By Finite Element Analysis

Objective: to study the biomechanical stability of the elastic intramedullary nail and new intramedullary nail which were compared in finite element analysis, and investigate the feasibility and superiority of the independently developed clavicle nail to treat clavicle fracture. Methods: 12 fresh adult clavicle specimens, all of which are no clavicle fracture, osteoporosis, cancer, deformities and other anomalies, randomly divided into three groups(A, B,): A group for the new intramedullary nail、 B group of elastic intramedullary nail. all the specimens in the middle of the same part of the clavicle bone were caused for establishing fracture models.Respectively using new intramedullary nail and elastic intramedullary nail fix fracture model. Above all fixed model are scanned by computed tomography(CT),the relative modeling software establish two groups of 3D finite element model :elastic intramedullary nail and new intramedullary nail. Each construct was tested in axial compression,three-piont bending, clockwise twist, and counterclockwise twist,which can evaluate the maximum equivalent stress and displacement of these models. The measurement results are analyzed statistically by SPSS13.0.Test results are indicated by using x ±s.The difference between the two groups is used by T test. there was no significant difference in p>0.05, p<0.05 difference was statistically significant. Results: In axialcompression,Themaximumequivalent displacement of new intramed ullary nail group is 0.55±0.05 mm,that of elastic intramedullary nail group is 0.61 ±0.04 mm, there is significant difference between two groups(P<0.05). the maximum equivalent stress of new intramedullary nail group is 48.45 ±17.48 Mpa. that of elastic intramedullary nail groupis 47.45 ± 16.58 Mpa, but no statistically significant difference was found.(P>0.05). Resistance to compression of NIN is better than elastic intramedullary nail group. There is no difference in stress distribution of internal fixation. In clockwise torsion condition, the maximum equivalent displacement of NIN group is 0.42±0.04 mm, that of EIN group is0.51±0.06 mm.Comparing the two groups is significant difference between two groups(P<0.05). the maximum equivalent stress of NIN group is 18.45±1.48 Mpa. that of EIN group is 17.45±2.36 Mpa. There was no statistical significance between the two groups.(P>0.05).In Counterclockwise torsion condition, the maximum equivalent displacement of NIN group is 0.52±0.03 mm,that of EIN group is0.61±0.04 mm.Comparing the two groups is significant difference between two groups(P<0.05). the maximum equivalent stress of NIN group is 48.45±1.25 Mpa, that of EIN group is 47.45±1.36 Mpa. There was no statistical significance between the two groups.(P>0.05). anti torsion ability of the NIN is stronger. Two groups have no difference instress distribution of internal fixation.In three-piont bending condition, the maximum equivalent displacement of NIN group is 0.35±0.02 mm,,that of EIN group is0.47±0.04 mm.There is significant difference between two groups(P<0.05). the maximum equivalent stress of NIN group is 38.45±2.35 Mpa, that of EIN group is 37.25±2.38 Mpa. There was no statistical significance between the two groups.(P>0.05). anti-bending ability of the NIN group is better than that of EIN group.Instress distribution of internal fixation has no difference. Conclusions: Above all,this study successfully construct three-dimensional finite element model which contains real geometrical figure after fixation and simulating biomechanical properties. Secondly,, through four conditions of simulation,this study confirms biomechanics stability of NIN is superior to EIN.