Improved myoelectric prosthesis control using targeted reinnervation surgery: a case series

Abstract

Targeted reinnervation is a surgical technique developed to increase the number of myoelectric input sites available to control an upper-limb prosthesis. Because signals from the nerves related to specific movements are used to control those missing degrees-of-freedom, the control of a prosthesis using this procedure is more physiologically appropriate compared to conventional control. This procedure has successfully been performed on three people with a shoulder disarticulation level amputation and three people with a transhumeral level amputation. Performance on timed tests, including the box-and-blocks test and clothespin test, has increased two to six times. Options for new control strategies are discussed.

Figures

Fig. 1

Timed tasks used to evaluate function pre-surgery and post-TMR: a) box and blocks, b) clothespin relocation task

Fig. 2

Results for all subjects for the Box and Blocks test. The left bar is the pre-surgical fitting and the right bar is the post-TMR fitting. All subjects had an increase in the number of blocks moved in 120s.

Fig. 3

Results for all subjects for the Clothespin relocation test. The left bar is the pre-surgical fitting and the right bar is the post-TMR fitting. All subjects reduced the amount of time required to move the three clothespins.

Fig. 4

Results for four subjects for the AMPS (Assessment of Motor and Process Skills) testing. Both motor and process scores are presented. SD-A did not perform the AMPS testing since these tasks were not possible with bilateral shoulder disarticulation prostheses. A change of .5 logits is considered to be significant. The cutoff for Motor skills is 2 and for Process skills is 1. Measures below the cutoffs indicate that there were problems that affected the quality or effectiveness of task performance.