181 Can Movement Modelling Software, in a Digital Preclinical Trial, Help Understand the Optimal Sit to Stand Motion Using Commercially Available Peripheral Nerve Stimulators?

Abstract

Abstract Aim Ethical approval is difficult to acquire for functional electrical stimulation trials, simulation may bridge the gap between FES concept and clinical trial approval. Using OpenSim modelling tool, this project aims to identify the minimum number of muscles, their strength and order of stimulation, that can produce the safest standing motion, using commercially available peripheral nerve stimulators. Method Modelling was executed using version 4.1 of OpenSim, utilising a previously validated, and extensively referred to, OpenSim lower limb model (Gait2354_Simbody) as the base model. Starting excitation values emulated previous literature for optimal sit to stand motion. EMG values were inputted using the excitation function of the forward dynamics tool, used to predict motion given defined neurological excitation values. Muscle groups and excitation values were altered iteratively to achieve the objective. Once the model performed the required function, within normal joint forces, the simulation was stopped. Results For optimal movement, the muscles required included, Gluteus Maximus, Rectus Femoris, Sartorius, Soleus, Tibialis Anterior, Vastus Intermedialis. This exceeded the 5-muscle objective, however muscles that shared a nervous supply could utilise a single FES port. Joint reaction forces remained within literature estimates, knee on tibia joint in the vertical plane achieved 2500N bilaterally, this represents a force equating to 3.64 times body weight. Conclusions Movement modelling software can become a fundamental tool in acquiring ethical approval for FES studies through simulation of full body motion. OpenSim requires iterative inputted improvements by the user, therefore a software which generates automated efficient movements would be more accurate and faster.