Abstract:
Reverse shoulder arthroplasty (RSA) addresses significant functional impairment in patients with rotator cuff deficiency and shoulder arthritis, yet remains complicated by instability issues related to implant design variations. This study employs finite element (FE) analysis to evaluate how different glenoid lateralizations (2mm, 4mm, and 10mm) and polyethylene liner designs (normal and retentive configurations) influence shoulder biomechanics post-RSA. FE models included accurate geometrical representations of the scapula, humerus, glenosphere implant, humeral components, and key muscles (deltoid, subscapularis, and infraspinatus), subjected to external rotation simulations to quantify biomechanical outcomes such as deltoid and subscapularis forces, range of motion without impingement, and joint stability metrics (subluxation gap). The findings reveal that increased glenoid lateralization enhanced impingement-free external rotation but concurrently amplified muscular forces, potentially elevating risks of scapular fracture and stress-induced bone remodeling. Additionally, retentive liners resulted in earlier impingement and higher subluxation compared to standard liners. This research highlights the delicate biomechanical trade-offs in RSA implant design, emphasizing the necessity for patient-specific computational modeling to guide clinical decisions toward optimized joint function and longevity.
