A Myoelectric Control System for Young Children

R. N. SCOTT,* V. A, DUNFIELD, P. D. RICHARD,J. W. HAYDEN, R. R. CALDWELL AND P. E. PAASCHIFredericton, New Brunswick


Noting that Rolf Sorbye demonstrated both the feasibility and the benefits of fitting congenital amputees as young as 18 months of age with myoelectric prostheses, even though he had to use adult components, we designed a new control system specifically for the very young child. Deficiencies in the Otto Bock control system include the electrodes which are too bulky for young children, the fact that the system is available for young children only as a two-state (two-muscle) system and the battery receptacle, if used, is too bulky. Deficiencies in the University of New Brunswick (UNB) control systems now available are that the units are too large and are only available as three-state (two-muscle) controls.

Design objectives for the new system were:

a)improved appearance

b) reduced weight

c) choice of two-state or three-state control in similar packages

d) choice of built-in or external battery

e) fast-charge option for built-in battery.

The first prototype of the new system was fitted briefly in February 1983, when certain design defects which had not been identified in bench testing became apparent. A redesign is essentially complete, with the first fitting of the redesign system scheduled for June 1983. The first system configuration to be completed is a three-state control with built-in battery, but systems with twostate control and the option of external battery with both control systems will be made available shortly.

The new system is designed to be used in conjunction with the hands made by Systemteknik, and permits fabrication of a below-elbow prosthesis with a weight of less than a pound including the built-in battery. Interference rejection of the new electronic control system is significantly better than that of present UNB systems, and an improved "battery saver" circuit is incorporated as a standard feature.

*Fredericton Myoelectric Prosthetics Clinic, Forest Hill Rehabilitation Centre, 180 Woodbridge Street, Fredericton, NB E3B 4R5 Canada