Comparative finite element analysis: internal fixation plate versus intramedullary nail for neer type III-VI proximal...

Finite element analysis (FEA) could advance the understanding of fracture fixation and guide the choice of surgical treatment. This study aimed to compare two internal fixation methods in the treatment of displaced proximal humeral fracture (PHF) through FEA.

Three-dimensional FEA model based on the left shoulder joint of a 67-year-old female patient with PHFs and osteoporosis was adopted, in order to analyze the fixation effect and load stress distribution of internal fixation plates with open reduction and intramedullary nails without opening the fracture in the treatment of Neer III-VI PHF.

The displacement of the distal humerus with intramedullary nail fixation was more obvious than that of the distal humerus with bone plate fixation, and the resistance of intramedullary nail fixation was less than that of bone plate fixation under the same stress load. Maximum stress on the screw when adopting the intramedullary nail fixation was smaller than that when adopting the internal fixation with the internal fixation plates. The strain data indicate that the strain of both the fixation device and the bone when adopting the internal fixation with the intramedullary nails is less than that when adopting the internal fixation with the internal fixation plates.

Biomechanical analysis demonstrated that for complex fracture types with osteoporosis intramedullary nail system without opening the fracture had better stress dispersion than internal fixation plates with open reduction, and the risk of failure of central fixation was lower.