Research on musculoskeletal model of elbow joint for evaluating the feasibility of FES.

Tremor usually occurs in a patient's upper limb with a roughly sinusoidal profile. Understanding the inner mechanism of the involuntary movement is fundamental to improving tremor suppression treatments. Therefore, the musculoskeletal model of the elbow joint was developed in this study. Initially, healthy subjects were selected to simulate tremor and the tremulous data was collected with the purpose of sparing patients from fatigue. With the recorded joint angle and surface EMG (sEMG), the model was calibrated to subjects by optimization approach. The activation derived from the electric pulse was employed to drive the tuned model and the model's output was compared with the angle predicted by the EMG-driven musculoskeletal model. The results demonstrated that the performance of the calibrated model was improved by a smaller normalized root mean square error and a higher coefficient of determination compared with the no-tuned model. There was no significant difference between the angles estimated by the tuned model activated by the electric pulse and muscle excitation. It indicates that neural activation could be replaced by the electric pulse to excite the limbs for desired angle. Therefore, the study presents a good way to evaluate the feasibility of Functional Electric Stimulation to suppress tremor.