Finite Element Analysis Of Different Internal Fixation Patterns For Volar Marginal Rim Fractures

Purpose:The biomechanical stability of volar marginal rim fractures was analyzed and compared with metacarpal hook plate,metacarpal mini plate and universal locking compression plate by finite element analysis method.Method:A healthy young volunteer was scanned by CT and the data was extracted.The right wrist was scanned by three-dimensional CT,and the results of DICOM images were extracted.First of all,the DICOM data are extracted from the radius by Mimics19.0 and optimized in parallel to generate a three-dimensional model of the radius.Then GeomagicStudio2013 is used to further examine and optimize the radius model to make it convenient for further processing.In Solidworks2017,the simulation of fracture and the assembly of steel plate and bone are carried out.Finally,the finite element analysis is carried out by using ANSYS19.0,the material properties in the model are assigned,the constraints are carried out,and the static analysis is carried out,and the stress and displacement under three kinds of internal fixation and three different working conditions are obtained.Result:The results of internal fixation of metacarpal hook plate,metacarpal miniature plate and universal locking compression plate are compared and analyzed,and the results are as follows:1.Comparative analysis of internal fixation stress: metacarpal hook plate(15.336MPa)< metacarpal mini-plate(17.521MPa)< universal compression plate(25.555MPa)under axial 100 N load,metacarpal hook plate(17.228MPa)< metacarpal mini-plate(28.95MPa)< universal compression plate(79.62MPa)under back extension 50 N load,metacarpal hook plate(17.228MPa)< metacarpal mini-plate(28.95MPa)< universal compression plate(79.62MPa).Under the load of 50 N metacarpal flexion,metacarpal hook plate(19.701MPa)< universal compression plate(91.872MPa)< metacarpal mini plate(211.68MPa).2.Comparative analysis of fracture stress: under axial 100 N load,metacarpal hook plate group(3.4272MPa)< metacarpal mini-plate group(3.7563MPa)< universal compression plate group(5.5772MPa),metacarpal hook plate group(4.127MPa)< universal compression plate group(4.8494MPa)< metacarpal mini-plate group(5.1121MPa),metacarpal hook plate group(4.127MPa)< universal compression plate group(5.1121MPa),metacarpal hook plate group(4.127MPa)< universal compression plate group(4.8494MPa)< metacarpal mini-plate group(5.1121MPa).Under the load of 50 N metacarpal flexion,metacarpal hook plate group(3.5581MPa)< universal compression plate group(6.8398MPa)< metacarpal mini steel plate group(7.5267MPa).3.Comparative analysis of distal radius articular surface displacement: under axial 100 N load,universal compression plate group(0.58919mm)< metacarpal hook plate group(0.68501mm)< metacarpal mini-plate group(0.68721mm),under dorsal extension 50 N load,universal compression plate group(7.3557mm)< metacarpal hook plate group(7.7254mm)< metacarpal mini-plate group(7.7386mm),and under the load of 50 N dorsal extension,universal compression plate group(7.3557mm)< metacarpal hook plate group(7.7254mm)< metacarpal mini-plate group(7.7386mm).Under the load of 50 N metacarpal flexion,universal compression plate group(7.6714mm)< metacarpal hook plate group(8.1009mm)< metacarpal mini steel plate group(8.2852mm).Conclusion:In terms of internal fixation stress and fracture block stress,metacarpal hook plate is better than metacarpal mini plate and universal compression plate.In the aspect of articular surface displacement of distal radius,universal compression plate is better than metacarpal hook plate and metacarpal miniature plate.In the early stage of postoperative functional rehabilitation,weight-bearing wrist dorsal extension and palmar flexion exercise should be avoided as far as possible.