2023, Vol. 27 ›› Issue (18): 2804-2808

Finite element analysis of different fibular support methods to reconstruct the poor medial column of humeral proximal fractures

Liu Yan1, Ge Hongqing2, Chen Wenzhi2, Liang Zeqian3, Li Junye1, He Jielong1   

Abstract: BACKGROUND: The method of fibular allograft to reconstruct the poor medial column of humeral proximal fractures has gradually been widely used in clinic, while the best support site in the intramedullary cavity is still controversial, and it is necessary to study its stability through biomechanical approach.  
OBJECTIVE: To explore the biomechanical stability of the fibula in the center of the medullary cavity, anterolateral, anteromedial, posterolateral, and posteromedial positions using a finite element analysis method.
METHODS:   The proximal humeral CT data of an osteoporosis female patient were obtained, modeled by Mimics 19.0 software and Geomagic Wrap software, and osteotomized in Soildworks 2017 software according to 5 mm below the anatomical neck of the humerus to establish a poor medial column support proximal humeral fracture model. The position of the fibula in the medullary cavity was divided into five groups. The fibula was located in center of the medullary cavity named F-C group; the fibula in anteromedial side of the medullary cavity named F-AL group; the fibula in anteromedial side of the medullary cavity named F-AM group; the fibula in posterolateral side of the medullary cavity named F-PL group; the fibula in posteromedial side of the medullary cavity named F-PM group. The data were imported into Ansys 2019 software to simulate the biomechanical stability of different grouping models under indirect violence.  
RESULTS AND CONCLUSION: (1) Under axial load of 600 N, humeral stress: F-PL group (49.706 MPa)   < F-C group (57.980 MPa) < F-AL group (58.519 MPa) < F-PM group (61.868 MPa) < F -AM group (63.886 MPa); internal fixation stress: F-AM group (106.310 MPa) < F-PM group (110.030 MPa) < F-C group (111.940 MPa) < F-PL group (114.320 MPa) < F-AL group (122.98 MPa). (2) Under 600 N axial loads, humeral deformation: F-PM group (0.352 mm) < F-PL group (0.416 mm) < F-C group (0.431 mm) < F-AM group (0.549 mm) < F-AL group (0.574 mm); internal fixation deformation: F-PM group (0.127 mm) < F-PL group (0.187 mm) < F-C group (0.191 mm) < F-AM group (0.272 mm) < F-AL group (0.290 mm). (3) Relative displacement of the fracture: F-PM group (0.048 mm) was approximately 0.54 times as large as the F-PL group (0.088 mm) and F-AM group (0.088 mm), and the F-C and F-AL groups were 0.067 mm and 0.103 mm. (4) The results of the study showed that the F-PM group had the least displacement and more distributed stresses, indicating that the biomechanical stability of placing the fibula on posteromedial side of the medullary cavity was better than that of placing the fibula in the center of the medullary cavity, and the biomechanical stability of placing the fibula on the lateral side of the medullary cavity was the worst.
Key words: proximal humerus fractures, proximal humeral internal locking system, bone grafting, finite element analysis, biomechanics