Application of a lateral intertubercular sulcus plate in the treatment of proximal humeral fractures: A finite element analysis and example in clinical practice

Abstract

Background: Inversion deformities caused by insufficient medial support are especially common when the PHILOS locking plate is used to treat proximal humeral fractures. Using finite element analysis, the present study aimed to compare the biomechanical properties of a PHILOS locking plate (PLP) and a PLP combined with a lateral intertubercular sulcus plate (PLP-LSP) in the fixation of proximal humeral fractures with loss of the medial column. We also present the results of a 69-year-old female patient with a comminuted fracture of the proximal right humerus (Neer type four-part fracture) who underwent successful surgical treatment with a PHILOS plate combined with an auxiliary lateral intertubercular sulcus plate. Methods: After creating a three-dimensional finite element model of a proximal humeral fracture with loss of the medial column, three implant models were established. A full-screw PLP was used in Group A, a PHILOS plate lacking medial screw support and an auxiliary plate (MPLP-LSP) was used in Group B, and a full-screw PLP-LSP was used in Group C. The three fixation models were applied to the proximal humeral fracture model, following which horizontal, compressive, and rotational loads were applied to the humerus model. We evaluated structural stiffness and stress distribution of the implant and compared displacement and angle changes among the three models. Results: Displacement and angle changes were smallest in Group C (PLP-LSP) compared to those in Group A and Group B. The implant model used in Group C also showed the highest structural rigidity, endured less von Misses stress, and had the strongest stability than that used in Group A and Group B. Conclusion: An LSP placed at the internodal grove not only aids in anatomical reduction but also provides effective lateral and medial support, thereby reducing stress on the PLP and providing better stability in patients with proximal humeral fractures.