| Background:Currently,the commonly accepted classification of tibial plateau fractures is Schatzker classification.However,the finite element analysis of tibial plateau fractures is mostly focused on the fractures of specific parts of the tibial plateau,such as posterolateral fractures,while the finite element analysis of Schatzker fractures of a certain classification is rarely studied.In addition Schatzker type Ⅵ tibial plateau fractures in clinical treatment,no specific treatment,primary treatment has a separate medial plate,single plate for outside and inside and outside,use a combination of three treatments as to what kind of treatment effect is best,at present there are only some one-on-one controlled clinical studies,and through the finite element method(fem)biomechanical simulation research,there is no effect.Objective:The three-dimensional finite element analysis method is adopted to Schatzker type Ⅵ tibial plateau fractures in a separate medial plate,single lateral steel plate and inside and outside steel joint under three different fixed way,respectively under different motion state namely load simulation of biomechanics,it is concluded that the stress of the blocks and internal fixation of fracture,and according to the results of biomechanical aspects of reference for clinical treatment.Methods:Use the three-dimensional modeling software build respectively Schatzker type Ⅵ tibial plateau fracture model,then according to the experiment design and principles of internal fixation of the medial plate alone,alone the lateral steel plate and the lateral steel plate joint model,three kinds of internal fixation and finally give each model respectively corresponding constraint and load(250 n,feet when standing on one foot when 1000 n,500 n,walk when run at 1500 n and other violent activities of 2000 n),simulate human tibial plateau fracture in different movement modes of stress and displacement.Then the obtained data were compared and tested by statistical methods and the corresponding conclusions were obtained.The results showed that the bone stress greater than 120 Mpa could lead to the bone stress absorption.The stress of internal fixator greater than 450 MPa can lead to irreversible deformation of internal fixator.The stress of the internal fixator is more than 600 MPa,which can lead to the fracture of the internal fixator.Fracture displacement greater than 1mm is not conducive to fracture healing,while fracture displacement greater than 2mm increases the incidence of traumatic arthritis.Results:Under the loads of 250 N,500N,1000 N,1500 and 2000 N,the maximum displacement of the lateral fracture mass was less than 0.8mm,the maximum displacement of the medial fracture mass was less than 0.9mm,the maximum stress of the lateral fracture mass was less than 55 Mpa,the maximum stress of the medial fracture mass was less than 28 Mpa,and the stress of the internal fixation mass was less than 152 Mpa.The results of the kruskal-wallis test were as follows: H=0.860,P > 0.05(adjusted P=0.651).According to the test standard of alpha =0.05,H0 was retained.Therefore,no difference was found between the three fixation methods in the displacement of the lateral fracture block.(2)displacement of medial fracture block: kruskal-wallis test results: H=0.816,P > 0.05(adjusted P=0.665).According to the test criteria of alpha =0.05,H0 was retained.It was considered that there was no difference in displacement of medial fracture block between the three fixation methods.The results of kruskal-wallis test showed that H=12.5,P < 0.05(P=0.002 after adjustment).According to the test standard of alpha =0.05,H0 was rejected,and the three fixation methods were considered to be different in stress of the lateral fracture block.After pintwo comparison,there was no difference in the stress of the lateral bone mass between the internal plate group and the double-plate group(P=0.231 after adjustment).There was a difference in the stress of the lateral bone mass between the inner plate group and the outer plate group(P < 0.05,P=0.001 after adjustment).There was no difference in the stress of the lateral bone mass between the two groups(P=0.231 after adjustment).Therefore,the stress of posterior lateral fracture block fixation with medial plate is small and statistically significant.(4)internal fracture block stress: kruskalwallis test results are: H=12.522,P < 0.05(P=0.002 after adjustment),according to the alpha =0.05 test standard,rejected H0,it is considered that the three fixation methods in the internal fracture block stress difference.After pin-two comparison,there was no difference in the stress of the medial bone mass between the internal plate group and the double-plate group(P=0.231 after adjustment).There was a difference in the stress of medial bone mass between the inner plate group and the outer plate group(P < 0.05,P=0.001 after adjustment).There was no difference in stress between the two groups(P=0.231 after adjustment).Therefore,the stress of posterior medial fracture block fixed by lateral plate is small and statistically significant.(5)internal fixation stress: kruskalwallis test results were: H=10.889,P < 0.05(adjusted P=0.004).According to the test standard of alpha =0.05,H0 was rejected,and the three fixation methods were considered different in terms of internal fixation stress.After pin-two comparison,there was no difference in the stress of the internal fixator between the inner steel group and the outer steel group(P=0.840 after adjustment).There was a difference in internal fixation stress between the internal plate group and the double-plate group(P < 0.05,P=0.004 after adjustment).There was no difference in internal fixation stress between the two groups(P=0.092 after adjustment).Conclusion:There was no obvious displacement of the medial and lateral fracture blocks under different loading in the three treatment methods,the displacement was all less than 0.9mm,and did not reach the standard values of 1mm and 2mm.Statistically,there was no significant difference between the three fixation methods in fracture block displacement,and all of them could achieve satisfactory surgical results.The three different fixation methods did not cause the maximum stress of the medial and lateral bone mass less than the yield stress of the tibia.According to the statistical results,the stress of posterior lateral fracture block fixed by medial plate was lower than that of posterior lateral fracture block fixed by lateral plate.However,because the lateral bone mass is smaller,it is more likely to be displaced after the instability of internal fixation,which leads to the failure of fixation.The medial bone mass is relatively large.From the perspective of fracture line,the contact area between the medial bone mass and the main bone is large and the Angle of fracture line is small,which is relatively less likely to cause the failure of fixation due to displacement after the instability of internal fixation.Therefore,the result of medial plate fixation is preferable.The maximum stress of internal fixation after internal fixation with medial plate,lateral plate and double plate did not reach the yield stress of deformation and fracture,which could achieve relatively stable and safe fixation.Statistical results: the stress of internal fixation after internal fixation with medial plate was small and statistically significant.In conclusion,all three internal fixation methods can achieve satisfactory results,and compared with other methods,medial plate fixation has more advantages and less damage to patients. |
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