**6. Limitations and future prospects**

There are several important limitations in the methodology of computer simulation. First, the bone model used in the simulation does not assess factors related to the soft tissue, including the labrum. Therefore, impingement simulation that includes consideration of the soft tissues may be required. Secondly, the simulation conditions, i.e., the variation of flexion angle, have not yet been fully established. In addition, the influence of pelvic tilt must be considered, as dynamic changes significantly influence the impingement location and simulated range of motion [10]. Currently, we use the functional pelvic plane as the reference plane; however, pelvic tilt would certainly be influenced by interventions, such as rehabilitation or surgery [11].
