Optimal Force Myography Placement For Maximizing Locomotion Classification Accuracy in Transfemoral Amputees: A Pilot Study.

Force myography (FMG), is shown to be a promising alternative to electromyography in locomotion classification. However, the placement of force myography sensors over the thigh during locomotion is not yet clear. To this end, an inhouse developed FMG strap was placed over the thigh muscles of healthy/amputees, while walking on different terrains. The performance of the system was tested on six healthy and two amputees during the five different placements of FMG strap i.e., base, distal, lateral, medial, and proximal. The study reveals that there is an increase in average accuracy (STD) from [mean (STD)] 96.4% (4.0) to 99.5% (0.5) for healthy individuals and 95.5% (3.0) to 99.1% (0.3) for amputees while moving the FMG strap to the proximal of the thigh/stump. The study further determines the combination of three FMG channels on anterior side (Rectus Femoris, Vastus lateralis, and Iliotibial Tract muscles) that provides classification accuracy at par (p > 0.05) to utilizing all eight channels for locomotion classification. The variation of humidity throughout the trials did not significantly (p > 0.05) affect the classification accuracy. The study concludes that the optimal location to place the FMG strap is proximal to the thigh/ stump with a minimum of three FMG channels on the anterior part of the thigh for superior classification accuracy.