Glenoid track evaluation by a validated finite-element shoulder numerical model

Background: The limits of the glenoid track have been defined through methods that do not take properly into account the physiological articular forces involved in the articular contact, which may interfere with its size. Finite elements numerical models can simulate joint forces more realistically. Objective: To evaluate the glenoid track in a finite element numerical model of the shoulder. Methods: We developed a finite element numerical model of the shoulder, based on imaging exams of a volunteer, including the proximal humerus, scapula, their respective articular cartilages, and the rotator cuff muscles. An algorithm to balance the weight of the arm calculated muscle, wrapping, and articular reaction forces. The model has freedom of translation in three axes. The articular contact characteristics and glenoid track's dimensions according to the literature references were evaluated in 60 degrees, 90 degrees and 120 degrees of abduction, all at the 90 degrees external rotation. Results: The model's anatomy and physiology were validated. The value of the glenoid track (according to Yamamoto's parameters) was 86% of glenoid length at 90 degrees abduction before loading of forces, and 79% afterwards. The glenoid track at 60 degrees, 90 degrees and 120 degrees of abduction (Omori's parameters) corresponded, respectively, to 71%, 88% and 104% of glenoid length before loading of forces, and 76%, 84% and 103% afterward. Conclusion: The numerical model is suitable for the shoulder articular contact evaluation. The articular contact analysis ratifies the glenoid track concept and contributes to its evolution. This value is influenced by glenohumeral joint forces, which should be considered for the analysis. (C) 2020 Elsevier Masson SAS. All rights reserved. (AU)