The H.M.R.C. Experience with the Single-Site Voluntary Opening Control System


Our early attempts to apply components and fitting/training strategies designed for N2-4 year old amputees to younger children were disappointing and resulted in a re-evaluation of our fitting criteria. This included: an assessment of functional and social requirements of the very young child, size and suitability of components as well as training and fitting techniques employed.

The availability of new components has enabled us to produce a cosmetically appealing, self-contained prosthesis that has radically changed our approach to pre-school fittings. This system includes a VASI 0-3 infant-sized electric hand, incorporating a single-site, voluntary opening, `cookie crusher' circuit attached to an Otto Bock 13E125 electrode and a four cell 150 mA battery pack. If a child is referred early, we now prescribe an initial preparatory passive fitting at 3 months of age and then proceed directly to a myoelectric fitting when the child is ready for activation.

Children as young as 10 months adjust well to the fitting of this lightweight myoelectric prosthesis and master the control strategy easily on their own without any need for formal control training. The children are often able to open their hands voluntarily within a few minutes of prosthetic application and participate in simple grasp and release play activities. The development of a bilateral pattern of use is a slower process, however, and requires maturation developed with a consistent wearing pattern and ongoing encouragement by care-givers.

HMRC has now fitted 30 young children with the single-site voluntary control system. While success is difficult to define or quantify, our observations at this time would suggest that if the prosthesis is worn regularly, the younger the children are fitted the more they exhibit spontaneous integration of the prosthesis into their daily activity.

350 Rumsey Road, Toronto, Ont. M4G IR8