Three-dimensional finite element analysis of mini-external fixation and Kirschner wire internal fixation in Bennett fracture treatment

Objective: To analyze the mini-external fixation and percutaneous K-wire internal fixation for the treatment of Bennett fracture by using finite element analysis and to compare the biomechanical stability and postoperative impact of the two fixations on the fracture. Methods: Three-dimensional digital models of the first metacarpal bone, second metacarpal bone, and the trapezium were established using Mimics 10.01 software. A solid model and finite element models were created and analyzed using ANSYS 10.0. The same load of 100 N was exerted on both the mini-external fixator and the Kirschner (K)-wire internal fixator for the treatment of Bennett fracture. Finally, the none-line solution was analyzed, and displacement nephograms were obtained. Results: The displacement nephograms of the distal and proximal fragments of the fracture obtained using the mini-external and K-wire models were established. The X/Y/Z (SUM)component displacements of 15 nodes aligned with the articular surface fracture were obtained. The relative displacement of the distal and the proximal fragments of the fracture were calculated, and all digits of relative displacement were entered into SPSS 13.0 software. The difference between the X-component relative displacements was statistically significant. Moreover, the comparison of the Y-component, Z-component, and SUM-component relative displacements yielded statistical significance. The average relative displacement in the X-direction was 0.3214 mm in the K-wire model. Conclusion: Mini-external fixation is more effective than K-wire internal fixation for secure Bennett fracture stability. Both fixations have similar effects on postoperative traumatic arthritis and postoperative hand functions. Level of evidence: 1 Biomechanical studies. (C) 2012 Elsevier Masson SAS. All rights reserved.