Biomechanics of humeral locking plate augmented with fibular strut allograft and intramedullary strut plate using finite element analysis

A humeral locking plate augmented with fibular strut allograft treated for proximal humeral fracture without internal structural support is satisfactory. While it is better clinically and biomechanically than the locking plate alone, it has disadvantages, including difficulty to obtain and the possibility of infection. Other alternative augmentation approaches are in demand. Therefore, the hypothesis of this study is whether intramedullary strut plate can replace fibular strut allograft as a surgical method while providing similar biomechanical performance. The finite element analysis (FEA) models were established based on three-dimensional computed tomography images. Computer-aided design implants were incorporated into the models. According to different implants, models were divided into four groups: the intact humerus, humeral locking plate alone (LP), humeral locking plate augmented with fibular strut allograft (FA), and humeral locking plate augmented with intramedullary strut plate (IMP). The displacements and von Mises stresses were measured on the models by simulating axial force, oblique force and torsion. Compared with the LP group, the displacements and von Mises stresses on the humerus and humeral locking plate in the FA, and IMP groups were all smaller in axial force, oblique force, and torsion. The biomechanical effects of FA and IMP in proximal humeral fracture without internal structural support were basically similar in terms of axial force, oblique force, and torsion. Findings provide useful new ideas for implant design. Our FEA simulation indicates that both the fibular strut allograft (FA) and intramedullary strut plate (IMP) offer similar biomechanical stability in treating proximal humeral fractures without internal structural support. This supports the hypothesis that the intramedullary strut plate can effectively replace the fibular strut allograft.