Novel cross-locking intramedullary nails for olecranon: a finite element analysis and specimen experiments / 中华创伤骨科杂志

ABSTRACT

Objective:To determine the mechanical properties of our self-designed novel cross-locking intramedullary nails and the impact of number of conical locking nails on the fixation through a finite element analysis and specimen experiments.Methods:Mimics 19.0 and SolidWorks 2014 were used to create transverse fracture models of the olecranon which were subjected to fixation with respectively K-wire tension band (KTB) and our self-designed novel cross-locking intramedullary nails (NIN). The strengths of KTB and NIN fixation were analyzed by Ansys. Fifteen human ulna specimens were used to construct a transverse fracture model of the olecranon; an Instron E10000 mechanical testing machine was used to determine mechanical properties in fixation respectively with KTB, one NIN (NIN-1) and 3 NINs (NIN-3).Results:In the finite element analysis, in simulation of the forearm flexed at 45° under a 100 N load, the deformation of the fracture surface of the olecranon in fixation with KTB, NIN-1 and NIN-3 was respectively 0.131 mm, 0.123 mm and 0.121 mm. In the specimen experiments, in simulation of the forearm flexed at 45°, the maximum failure loads for fixation with KTB, NIN-1 and NIN-3 were (313.38±27.68) N, (528.56±53.58) N and (871.04±94.95) N, respectively, showing significant differences among the 3 groups ( P<0.05). The maximum failure load for NIN-3 fixation was significantly greater than that for KTB or NIN-1 fixation, and the maximum failure load for NIN-1 fixation was significantly greater than that for KTB fixation ( P<0.05). Conclusions:Compared with KTB fixation, NIN fixation is more convenient in operation and has better mechanical properties. NIN-3 fixation has the best mechanical properties.