Finite element analysis of antegrade and retrograde internal intramedullary nailing for mid-shaft clavicle fracture.

INTRODUCTION

Titanium elastic nail (TEN) fixation is a commonly used intramedullary technique, favored for its minimal incision, elastic fixation, and shorter healing time. However, the stability of TEN fixation is not always assured. We developed a new surgical approach for TEN fixation that has shown excellent clinical outcomes. This study aimed to perform a finite element analysis comparing the traditional antegrade internal TEN (ATEN) biomechanical characteristics with retrograde lateral TEN (RTEN) fixations for mid-shaft clavicle fractures.

MATERIALS AND METHODS

The CT images were obtained from the right clavicle of a 40-year-old male volunteer. Models of intact and mid-shaft clavicle fractures fixed using ATEN and RTEN were constructed. Distal clavicle displacement, von Mises stress, and von Mises strain were measured under compressive axial loading and cantilever bending loading.

RESULTS

The stiffness of both TEN fixation models was lower than that of the intact clavicle under both loading conditions. However, when comparing the two fixation methods, RTEN demonstrated higher stiffness than ATEN under both cantilever bending loading (43.05% vs. 38.57%) and axial compression loading (25.73% vs. 22.44%). The peak von Mises stresses of 2 TEN models were both concentrated on the implants, with RTEN showing lower peak stress than ATEN in both conditions (1090.4 MPa vs. 1371.3 MPa under cantilever bending loading and 1112.9 MPa vs. 1433.8 MPa under axial compression loading).

CONCLUSION

Compared to ATEN, RTEN exhibits superior biomechanical properties, with higher stiffness and lower peak von Mises stress. This suggests that RTEN may allow for a shorter immobilization period and earlier rehabilitation, while also presenting a lower risk of fixation failure, such as bending or disruption. Simulation is promising but clinical studies need to be pursued before concluding that retrograde nailing is superior in consideration of the anatomy.

CLINICAL TRIAL NUMBER

Not applicable.