“…When patients in this study were investigated, the current musculoskeletal model displayed moderate improvement over the original version: the T9PA parameter was predicted with accuracy, PPV, NPV, sensitivity, and specificity values as 0.93, 0.93, 0.92, 0.93, and 0.92, respectively, compared with 0.89, 0.88, 0.92, 0.93, and 0.87, for the original model. 19 The cone-of-economy suggests that ideal alignment allows for a balanced standing posture that requires minimal muscle effort. 29 Utilizing this concept, we predicted postoperative sagittal alignment corresponding to minimum muscle activation and, thus, biomechanically, the most ergonomic.…”