The Dysmelic Child And The Carbon Dioxide Prosthesis

Aline Macnaughtan, O.T.


The severe congenital limb deformities caused by the drug thalidomide in 1960 acted as a stimulant to the production of powered artificial arms. Prostheses powered by CO2 had already been developed in Germany by Marquardt and it was with limbs of this type that training of Scotland's thalidomide children began.

The training of dysmelic children is conducted in a self-care unit attached to the hospital. This unit has accommodations for two mothers and six children. The children, who come from all over Scotland and Northern Ireland, are admitted to the unit for periods of from one to four weeks. During this time their prostheses are renewed or mended and the occupational therapist has an opportunity to assess their progress in self-care activities and to give training in the use of their prostheses. The mothers are able to watch and absorb the training methods in relaxed surroundings.

Children Fitted With Prostheses

The two main groups of children to be fitted with artificial arms are those with bilateral phocomelia and those with bilateral amelia. In cases of bilateral phocomelia the decision to fit or not to fit is based on the results of a functional assessment made on the affected limbs. This assessment determines whether or not the child is capable of bringing either of his short limbs to his mouth and of reaching across his chest to manipulate toys in bimanual play (Fig. 1 and 2 ). The condition of his fingers with regard to flexion deformities, muscle power and grip is charted. This simple appraisal of the phocomelic limbs gives some indication as to which children should be trained to use their own resources and which should use their rudimentary fingers for the operation of switches to control powered limbs. Of 20 children fitted with CO2 prostheses, nine phocomelics no longer use artificial limbs because of increased finger function and limb growth.

The youngest child fitted (in September 1963) was a ten-month-old baby girl, who had bilateral amelia with a rudimentary digit attached to one shoulder. This digit was weak, but looked as though it could develop enough power to operate a switch. The child was hardly aware of the digit and a daily routine of exercise was instituted to determine its potential (Fig. 3 ). Toys, squeakers and bells placed beside the digit soon provided information as to which movements could be harnessed most successfully to move the switch. The Heidelberg limbs, which the child wore, brought two rubber mittens together by internal rotation at both elbow joints (Fig. 4 ). The child had been introduced to bilateral cosmetic arms as soon as sitting balance had been gained. This experience expedited her acclimatization to the powered limb suspension. At first, the movement of the powered limbs was completely haphazard, as would be expected of a child so young, but its value in laying the foundation of a movement pattern was evident when the child graduated to more sophisticated limbs. By the age of 18 months she was able to grasp toys with purpose and it was then that she was introduced to the limbs which were being developed by a newly formed team of engineers in Edinburgh under the direction of Dr. D. C. Simpson.

Training

Children are trained to use powered limbs in several stages. First the child learns to tolerate the prosthesis, which is effected by gentle introduction at an early age. The next step involves concentration on the control sites which will be used to operate the limb. After the child has become familiar with each individual limb movement, the combination of movements to perform more advanced tasks must be taught.

Movements to operate switches come from either the shoulders or the digits. Other means of operation, such as by chest expansion or chin control, are not used in Scotland.

At 18 to 24 months a child is given a limb with one control, which actuates elbow flexion and extension. The control point, whether it be digital or shoulder, is always on the same side as the powered unit. The benefit of this method of control can be seen when the child is being trained to feed himself. The incentive is strong and the child learns quickly. The elbow mechanism is based on the parallelogram principle which, among other things, allows a spoonful of food to arrive at the mouth in a horizontal position. The hook, which is passive, is preloaded with a spoon or biscuit, and is kept closed by a rubber band. The use of a second control is introduced shortly thereafter (usually one to two weeks) to give active control of the hook (Fig. 5 ).

Control of the Terminal Device

The control of the hook may be by means of a digit, or the shoulder on the opposite side from the powered arm. In cases of bilateral amelia where one digit is present, the hook control is operated by this digit, irrespective of the shoulder to which it is attached. To the child the image of a digit is possibly more closely associated with grasp and it is with this in mind that the positioning of the switch is arranged. With two powered units, the training of the child is augmented with many additional activities which include the use of action toys. The most useful of these are building baskets, pegboards, bricks, rod and bead sets, and any other toy which gives practice in grasping, lifting, positioning and releasing. Two factors govern the choice of toys. One is the hook opening (1 1/2 inches when fully opened), and the other is that the toys must be capable of use with one arm only. It is the practice at this centre to fit one powered arm and one cosmetic arm to a child with severe bilateral deficits.

Third Control Added

When the child has become competent in the operation of two controls, a third one is added. This typically does not happen before the child is three years old. The third control provides wrist rotation and the source of control is on the shoulder opposite to the one fitted with the powered limb. If the child is phocomelic, the same principle applies. The availability of three controls opens up a whole new vista of activities. The one most readily apparent is a more polished performance at the dinner table (Fig. 6 ). It is somewhat difficult to find toys and games to provide training for the wrist function. The wrist unit furnishes 160 degrees of movement from the fully pronated position. However, some games which have been useful are playing cards, bubble-blowing, painting, pouring liquids from one container to another (Fig. 7 ), and "posting" shapes in boxes (Fig. 8 ). The child contributes to this training in an informal manner by examining everything he comes across whether it is rubbish in the waste paper basket or mud from the garden.

Position-Servo Controls

Between the times spent in training the child in the use of the prosthesis, exercises for the shoulders, fingers, and trunk are given to promote optimum power and movement. It is important that the shoulders maintain maximum mobility to make use of the position-servo controls which in 1965 replaced many of the two-way switches.

When the child operates a servo switch, he has to understand that whenever the shoulder or digit exerts pressure on the switch the limb will move proportionately as far as the switch travels. For instance, if the child wishes the arm to stay midway between flexion and extension, he must be able to sustain pressure on the control when it has reached the midpoint of its excursion. This gives a degree of sensory feedback which helps to develop the child's awareness of position. In training, this feedback may be illustrated by asking the child to draw a line at top, middle, and bottom points on a blackboard held in a vertical position, and then to repeat the experiment with his eyes shut. A remarkable degree of accuracy is achieved after very little practice and the child enjoys this new skill, as any attempt to simulate the normal arm function is enthusiastically pursued.

Dual Terminal-Device Operation

In order to provide the child with greater scope the cosmetic arm, which balances the powered arm, is fitted with a powered split hook which operates simultaneously with its neighbor. The value of this arrangement is found in activities such as pushing a doll's pram or a wheelbarrow, or riding a tricycle. It also allows the child to pick up an object with whichever arm is nearer (Fig. 9 ) but does not allow bimanual play because the hooks open simultaneously.

Several children have been fitted with Otto Bock hands which operate on the same system as the hooks. The hand on the dominant side is attached to the wrist unit at a flexion angle of 45 degrees so as to provide the best angle for prehension. This provision is necessary only on the dominant side to which the parallel movement unit is fitted.

In a series of tests with one of these children, it has been found that his performance with the hooks was slightly better than with the hands, but the child accepted the small deficit in function because of the cosmetic appeal of the hands (Fig. 10 ).

As the children grow older and wish to undertake more advanced tasks, those who have been very dependent on toe function are now happy to augment their feet with greater hook use. This use is readily seen at school where a child who wishes to be more like his classmates prefers to write holding a pencil with his hook or hand rather than to sit on the floor and use his toes (Fig. 11 and 12 ).

School Attendance

The schools which the children' attend are visited from time to time by the occupational therapist who shows the teacher how the prostheses work and suggests ways in which the child can adapt to the school routine. Simple devices such as magnets on metal boards, for example, can be used to hold exercise books and paper securely. Usually the teacher also sees to the refueling of the limbs, which is done by personnel of the British Oxygen Corporation who collect, refill, and deliver the crates of cylinders at regular intervals. A child may use up to six cylinders a day out of his regular supply of 42.

Clothing

Clothing usually has to be adapted so that the child may dress himself. This adaptation also makes it easier and quicker for the mother to dress him.* Part of the training of the child is devoted to dressing practice and the mother is encouraged to do as much altering and sewing of clothing as she can during her stay in the unit. The use of Velcro fastening has been a great help to the child who otherwise has to struggle to fasten his clothes. It also allows some children to go to the lavatory alone, which is a factor much appreciated by educational authorities when the child is placed in school.

Most of the children wear their prostheses all day and consequently breakages are common, particularly if the child has a flair for fighting or football.

The limbs which are currently being used have friction shoulder joints which limit the child's ability to reach across a working surface. A limb which will overcome this difficulty has now been designed. It has a powered shoulder unit which works in conjunction with the elbow and wrist units to provide an action simulating that of the human arm. This powered-shoulder joint prosthesis should be in use before long and its value will be carefully assessed.

Acknowledgement

My thanks to Dr. D. W. Lamb, Orthopaedic Surgeon, and Dr. D. C. Simpson, Physicist, for the encouragement and help given me in the treatment of our severely handicapped children.

"Miss Macnaughtan discusses the subject of adaptive clothing more fully in the publication "Clothing for the Limb Deficient Child."-Editor.

Aline Macnaughtan, O.T. is associated with the Princess Margaret Rose Orthopaedic Hospital in Edinburg, Scotland