Biomechanical evaluation with finite element analysis of the reconstruction of femoral tumor defects by using a double-barrel free vascularized fibular graft combined with a locking plate.

The repair of large distal femoral tumor defects can be challenging for orthopedic surgeons. The combination of a double-barrel free vascularized fibular graft (DFVFG) with a locking plate is a viable option. However, the biomechanical influence of the fibular bone length on the locking plate attachment is unclear. We aimed to evaluate the stability of the distal femoral defect after reconstruction with fibular grafts of different lengths. A three-dimensional model of a healthy volunteer was developed using computed tomography images. A locking plate and bicortical screws were constructed and registered with CAD. Four models were defined (6 cm, 8 cm, 10 cm, and 12 cm bone grafts). The models were imported into finite element analysis software. Boundary-constrained and load conditions were applied. The model stress distribution and displacement were statistically analyzed. The Von Mises stress distributions were similar between the 6 cm, 8 cm, and 10 cm bone grafts and locking plate within each of those bone defect models (P > 0.05), while the Von Mises stress distribution was significantly higher in the 12 cm model than the other 3 lengths for both the bone graft and locking plate (P < 0.05). Significantly greater Von Mises stress was observed at the 12 cm bone graft and locking plate than with the shorter bone grafts. Therefore, we recommend that, to avoid complications, the bone graft should not exceed 12 cm when using FVFG in combination with a locking plate while treating a distal femoral tumor defect.