Anti-rotational Plate With Intramedullary Nailing Stabilize Femoral Shaft Fracture Nonunions:Abiomechanical Study

Augmentation plating(Anti-rotational plating)+Retained IM with autogenous bone grafting is one of most common treatment for femoral shaft nounion after femoral nailing.Most literatures so far have reported its union rate was 100%.But it's rare to see the literature regarding how to use it reasonably.The purpose of this study was to determine the biomechanical effects of treating femoral fracture nonunions with an Anti-rotational plate in addition to Intramedullary nailing to provide a theoretical basis for their clinical application.Twenty-five synthetic bones selected for this experiment were randomly divided into the experimental(Anti-rotational plate group IM+AP)andcontrolgroups(Intramedullary nailing group IM).The experimental group included four subgroups based on the number of screws and fixation method: 2-bicortical conventionalscrewsgroup(P2)and 3-bicortical conventional screws group(P3),2-unicortical locking screws group(L2)and 3-unicortical locking screws group(L3).The experimental model was constructed in which their ends were embedded in the embedding apparatus.The specimens were affixed to the mechanical testing system.Torsion testing was performed until each specimen's failure,while their torsional angle and torque values were recorded.Results are as following: The mean value of the anti-torsional strength in theAnti-rotational plate group was greater than that in the Intramedullary nailing group(F=7.223,P<0.05),which was statistically significant.Based on the comparisons betweenthe subgroupsof Anti-rotational plate group,when the torsion angle turned to 25°,the mean value in the 3-bicortical conventional screws group(P3)(46512±6659Nm)was greater than the 2-bicortical conventional screws group(P2)(39033±8515Nm,F=9.688,P=0.034,P<0.05),which was statistically significant.When the torsion angle turned to 5°,10°,25°,the mean value in the 3-unicortical locking screws group(L3)(13479±1680,23289±3718,48194±5343Nm)was greater than the2-unicortical locking screws group(L2)(9500±3616,16989±5485,38687±6559Nm,F=8.407,P=0.017?P=0.031?P=0.026,P<0.05),which was statistically significant.When the torsion angle turned to 20°,25°,the mean value in the 3-unicortical locking screws group(L3)(39148±5074,48194±5343Nm)was greater thanthe2-bicorticalconventionalscrewsgroup(P2)(32496±5648,39033±8515Nm),F=9.688,P=0.035?P=0.014,P<0.05 whichwasstatisticallysignificant.Several conclusions have been drawn from the experiment: The anti-torsional strength in the Anti-rotational plate group was stronger than that in the Intramedullary nailing group.The Anti-torsional strength of 3-screws groups was stronger than of the 2-screws groups.But the Anti-torsional strength were no difference between unicortical locking screws groups and bicortical conventional screws groups if there had same screws at each side of the fracture site.Anti-rotational plate group with three bicortical conventional screws or Anti-rotational plate group with three unicortical locking screws gave the strongest fixation,suggesting it should be used in the clinic for treating femoral shaft fracture nonunions.