Establishment of finite element model and biomechanical analysis of external fixation and combined external and internal fixation for bone transport in treatment of a case with bone defect of lower limb / 中华显微外科杂志

ABSTRACT

Objective:To establish a finite element model for bone transport before surgery in the treatment of femoral and tibial bone defects with external fixation and combined intramedullary nails with external fixations, and evaluate the stability and properties of biomechanics.Methods:Between May 2022 and August 2022, a male volunteer in the Department of Trauma and Microreconstructive Surgery, the First Affiliated Hospital of Xinjiang Medical University was selected. The right lower limb was scanned using 64-slice CT. Data were imported into Mimics 21.0 to establish normal geometric models of femur and tibia. The models were arranged in 4 groups: a femoral external fixator group, a femoral external fixator combined with intramedullary nail group, a tibial external fixator group and a tibial external fixator combined with intramedullary nail group. Hypermesh 10.0 was used for meshing. Finite element analysis was performed by Ansys v.11 to measure the distribution and characteristics of equivalent stress in the transported bone segment, proximal and distal tibia, and fixtures in the 2 treatment modalities, respectively.Results:Peak Von Mises equivalent stress of cortical bone and external fixation was found higher in both of the femoral and tibial external fixator combined with intramedullary nail groups than that in the external fixator group, with stress reduction on cortical bone at approximately 76.9% and 77.8%, respectively. The stress reduction on external fixator was about 81.4% and 76.3%, respectively. Peak displacement of the structure in both of the femoral and tibial external fixator combined with intramedullary nail groups was lower than that in the external fixator group, with 78.4% and 60.1% reduction in displacement, respectively.Conclusion:Bone transport with intramedullary nailing combined with external fixator in treatment of femoral and tibial defects would offer better biomechanical advantages. It can facilitates bone regeneration and bone mineralisation during distraction phase and consolidation phase.