A CAD-to-Simulink framework for evaluating impingement-free motion in reverse total shoulder arthroplasty

Accurate characterization of impingement-free range of motion (ROM) following reverse total shoulder arthroplasty (RTSA) is essential for implant design and surgical planning. Existing computational methods often rely on mesh-overlap or clearance-based estimations, which can limit geometric accuracy. This study introduces and validates a CAD-to-Simulink computational pipeline that predicts impingement-free ROM using a high-resolution, point-cloud-based collision detection approach. Computer models of shoulder bony anatomy and generic RTSA implant components were assembled in SolidWorks and exported to MATLAB. Automated scripts executed humeral motion sweeps across planes of elevation. Point clouds were seeded on the acromion, coracoid, and scapular neck and used to detect impingement when penetration depth ≥1 mm. Three neck-shaft angles (155°, 145°, 135°) were evaluated. The 155° configuration was validated experimentally using additive manufactured monoblocs mounted on a custom-made frame under a 15 N compressive load. Sensitivity analyses examined the influence of point cloud density and spacing on impingement detection accuracy. Computational results demonstrated that decreasing the neck-shaft angle from 155° to 135° increased impingement-free ROM across evaluated planes, with improvements of up to 23°. This gain was attributed to delayed inferior impingement during adduction. Experimental validation closely aligned with predictions, showing impingement at 61.4° (superior) and 20.9° (inferior), compared to predicted values of 61.4° and 21.0°. Sensitivity analyses highlighted the importance of point cloud placement along key scapular regions. The CAD-to-Simulink framework provides a validated, reproducible, Finite Element Method independent prediction of impingement-free ROM, providing a kinematically accurate tool to optimize implant geometry and surgical positioning in RTSA.