Biomachanic Comparison Of The Internal Fixation Stability Of Different Instrumentations On Hoffa Fracture By Finite Element Analysis

Purpose:1.The forces of Hoffa fractures were analyzed with locking plate and hollow screw respectively2.From the perspective of mechanics,the effectiveness of locking plate,hollow screw,and steel plate combined with hollow screw in the fixation of Hoffa fractures was evaluated.Methods:A Hoffa fracture patient who underwent internal fixation in the orthopaedics department of our hospital was selected.Postoperative 3d CT scan of the left knee was performed,saved in DICOM format,and output.DICOM data were imported into Mimics 19.0 to reconstruct the bone model,and STL file was generated.And the file will be imported into Geomagic Studio 2013.The model generated by Mimics will be optimized and smoothed to get an accurate analysis model.The model is then imported into Solidworks 2017 for assembly processing to remove overlaps.Then,in ANSYS17.0,the model is assigned material attributes,constrained,and loaded.Finally analysis,output a variety of graphs.The interaction between the fracture block and the internal fixator in the cloud image was discussedThe fracture was fixed with hollow screws and locking plates.Therefore,three internal fixed model groups are created during the modeling process?Steel plate fixation group ? Hollow screw group ? Locking plate+Hollow screw group,Combined with the influencing factors such as body weight and bone mass,9sets of experimental data were collected from the three internal fixation model groups,and then analyzedResultsComparative analysis was made on the performance of internal fixation in the locking plate group,hollow screw group and hollow screw + locking plate group in normal bone and osteoporosis,and the results were shown in table 1,table 2 and table 3.Table1 Steel plate fixation group(values in the table are the maximum)Conclusion:Three internal fixation methods were evaluated from three aspects,namely,the stress of internal fixator,the stress around bone,and the degree of fracture block displacement.It was concluded that none of the three internal fixation methods for Hoffa fractures showed bone destruction,irreversible bending or fracture of internal fixator,etc.However,the displacement of fracture ends with hollow screw fixation is large,and the normal bone is 3.8433-6.0035mm,and the loose bone is 4.2756-5.847mm,greater than 1mm,which is not conducive to fracture healing.In the locking plate group,the stress distribution was average,the bone shear force was small,and the fracture displacement was small.In addition,the hollow screw +locking plate group with two additional hollow screws had the same fixation effect as the locking plate group.Therefore,from the perspective of mechanical analysis,it is recommended to use locking plate for fixation when Hoffa fractures are fixed.