Iomechanical Study Of Internal Fixation For Transverse Patellar Fracture

Objective:To study the biomechanical properties of Kirschner wire tension band,half-screw cannulated screw,full-screw cannulated screw,half-screw cannulated screw tension band and full-screw cannulated screw tension band in the treatment of transverse patella fracture.Methods:A total of 30 knee specimens were used for the biomechanical study,and all of the patellar were modeled to simulate a standardized transverse fracture of the patella(AO-34-C1).They were randomly divided into 5 groups with 6specimens in each group.Group A was fixed with Kirschner wire tension band,group B was fixed with half-screw hollow screw,group C was fixed with full-screw hollow screw,group D was fixed with half-screw hollow screw tension band,and group E was fixed with full-screw hollow screw tension band.The knee specimen was fixed on the test mold after flexion of 90 degrees,and the static pulling test was carried out by connecting the electronic universal testing machine.When the broken end of the patella was moved more than2 mm,the failure of internal fixation of the patella was determined,and the ultimate load and stability data of each group could be measured.Result:When the transverse fracture of patella failed,the ultimate load that group A could bear was 640.00±8.16 N,group B was 676.67±16.99 N,group C was688.33±26.09 N,group D was 781.67±13.44 N,and group E was 905.00±17.08 N.Except that there was no statistical difference between group B and C(P>0.05),and there were significant statistical differences among other groups(P<0.01).In the process of 0-600 N loading,the stability of group A is greater than that of group B(P<0.01)and group C(P<0.05),less than that of group E(P<0.01),there was no statistically significant difference between group D(P>0.05).The stability of group B was lower than that of group C(P<0.05).The stability of group D was similar to that of group E,with statistical difference only at 300 N and 600N(P<0.05).Conclusion:The traditional Kirschner wire tension band is still an effective method to fix the transverse fracture of patella.Half-threaded hollow screws and full-threaded hollow screws can bear large loads but have poor stability,so they have higher risks when used alone.Half-threaded hollow screw tension bands can withstand large loads and stability,and are close to Kirschner wire tension bands,which is an acceptable method.Full screw hollow screw tension band has high load resistance and good stability,which can be used as an alternative method of Kirschner wire tension band.