The numerical analysis results for biomechanical behavior depend on the fidelity of the shoulder joint biomodel and the mesh discretization, a factor often overlooked in soft-tissue analysis. This study evaluates the sensitivity of numerical simulations to element size in a detailed shoulder biomodel. Results demonstrate that output variability is highly specific to structures based on the number of nodes and elements that the structure’s biomodel has. A change from 0.8 mm to 1.0 mm elements induced a 30% variation in coracohumeral displacement and a staggering 65% difference at 90° of arm elevation. The articular capsule varied by 2% to 11%; the GLH inferior showed an 80% on stress variation during arm abduction at different angles. In contrast, the labrum showed substantial dependence on mesh discretization, with elongation increasing from 0.24005 mm to 1.6934 mm when the mesh was coarse. These findings highlight that even a minimal change in mesh discretization can yield different biomechanical predictions, compromising the clinical validity of computational models.