3D Finite Element Analysis of the Modular Prosthesis with Tooth Mechanism of the Femoral Shaft.

OBJECTIVES

To evaluate the mechanical properties and provide a theoretical basis of a diaphyseal prosthesis with tooth mechanism using the finite element analysis method from the point of view of biomechanics.

METHODS

A 3D digital femur model was generated based on a 28-year-old healthy man's femoral computed tomography (CT) data in Mimics 17.0 and the customized diaphyseal prostheses with/without tooth mechanism were designed in SolidWorks 2016. The 3D femur model after 8 cm osteotomy in the middle of its shaft and the prostheses with/without tooth mechanism was imported into Abaqus 2016 and the finite element analysis models were established. Three biomechanical tests (compression test, torsion test, and 3P-bending test) under broken load were simulated in FEA to evaluate the performance of the prostheses.

RESULTS

The stress distributions of the two prostheses were similar and the maximum von Mises stresses placed on them were very close in each test. The maximum von Mises stresses on the prosthesis with tooth mechanism were 31.55, 319.7, and 447.4 MPa, respectively, and those on the prosthesis without tooth mechanism were 26.26, 300.4, and 455.2 MPa, respectively, in the compression, torsion, and 3P-bending tests. The maximum von Mises stresses on them were far below the ultimate tensile strength or ultimate compressive strength of the titanium alloy.

CONCLUSIONS

The diaphyseal prosthesis with tooth mechanism is helpful to adjust the rotation of the long bone during operation. Compared with the conventional diaphyseal prosthesis (without tooth mechanism), the diaphyseal prosthesis with tooth mechanism also has a good biomechanical performance and does not increase the risk of prosthetic failure.