Terminal Device Activation for Infant Amputees

Elaine Trefler, P. & O. T. Reg.

The terminal device fitted to the prosthesis of a child with a congenital above-elbow or below-elbow amputation is usually activated when a child is about two years of age. This activation is almost always followed by several weeks of training. In the experience of this Centre, this timetable has presented a number of drawbacks:

  • A child is ready for bilateral grasp before he reaches the age of two years.

  • A child is difficult to work with after he reaches the "terrible twos" stage of hyperactivity and negativism.

  • If activation is delayed until the child is two years old he may already have developed compensatory patterns which could have been more easily prevented than they can be broken.

For these reasons we now begin activation of the terminal device when the infant is 15 months of age. The advantages of this procedure are:

  • We find the 15-month-old child easy to work with for short periods of time. He has an attention span of one or two minutes.

  • The cable system, when applied to the prosthesis of an infant, often helps to eliminate the problem of excessive internal rotation of the socket.

  • The availability of active grasp can enhance the activity pattern of an intelligent child.

We have not found any disadvantages to activating the terminal device early as the cable does not restrict any of the movements necessary for the child's play.


After the cable is applied to the prosthesis, two types of training are given. The first and most important part of training for a 15-month-old child is the instruction given to the parent(s). The mother is shown the pathway which the cable follows and the body control movements necessary to open and close the hook. She is told that her child will probably learn to operate the terminal device in the following sequence:

  1. Releasing an object from the terminal device.

  2. Relaxing after an object is placed in the device.

  3. Reaching for an object to be placed in the device.

  4. Placing objects in the terminal device himself.

  5. Operating bimanually with the terminal device and the sound hand at the midline of the body.

A variety of games which produce the desired body-control movements are demonstrated. Finally it is stressed that the mother can encourage her child but should not force him into a situation in which he must use the terminal device. The child will usually discover its best uses by himself.

The second type of training is with the child. He is shown that the hook holds objects and by performing certain movements he can drop toys, preferably those falling with a loud noise. He is seen once a week for a half-hour session over a period of three or four weeks. The rest of the time he is left to play either by himself or with the guidance of his parents.


In the past nine months we have activated the prostheses of seven children with congenital amputations at 15 months of age: two above-elbow and five below-elbow. Of these seven, only one is not currently using his terminal device spontaneously. Of course these children are still young and we have no assurance that they will continue to use their prostheses proficiently as they mature.


The contribution of Mrs. Marilyn Ross who instigated the program described in this report, is gratefully acknowledged.

Elaine Trefler, P. & O. T. Reg. is associated with Ontario Crippled Children's Centre Toronto, Canada