Pneumatic Arm Prostheses In Children

Ernst Marquardt, M.D.


(The following article by Dr. Ernst Marquardt, of the University of Heidelberg's Orthopedic Clinic, appeared in Jahrbuch der Fuersorge fuer Koerperbehinderte 1962, a yearbook published in West Germany by the German Association for the Help of the Disabled.)

Our experience indicates that it is desirable to fit a pneumatic prosthesis to an upper-extremity amputee at the age of four or five when the child has insufficient muscle power and shoulder girdle dimensions tc effectively operate a body powered prosthesis. This is true, for example, in children with bilateral loss of arms or hands. A child of this type must be able to bring his artificial "grasp organ" into all functional positions and have secure grasp with his artificial hand, in order to engage in eating, drinking, playing, school and handicraft activities. To achieve a satisfactory result, external power is necessary - in our case pneumatic servomotors which, although simply controlled by weak muscle power, make strong joint motions possible.

Case One

In the spring of 1957, we had our first opportunity to study the problems of fitting a little girl born without arms. At the age of four she had received a "grasp-arm" with a hook in the United States, but was referred to us when fitting was unsuccessful despite the best adaption and training. At first we substituted a pneumatic hand for a hook and a pneumatic hand turn joint was built in (Fig. 1 ). After three days, the child, then five years old, was able to eat, play and paint with the prosthesis.

As depicted in Fig. 1 , hand operation is pneumatically controlled by forward motion of the shoulder over a dual suction valve, while 180° hand pronation-supination is mechanically controlled by left shoulder elevation. A thigh belt actuates the motions of the elbow joint which is stabilized by a small chin lever. The two axis shoulder joint at the above-elbow rotation joint is passively adjustable.

In 1959, upon the request of her father, a pneumatic elbow joint (Fig. 2A and Fig. 2B ) was substituted for the mechanical elbow joint, making operation much easier. In the spring of 1962, she received her second pneumatic prosthesis which utilized many parts of the initial prosthesis -the hand, the hand-turn joint, the passive above-elbow rotation joint, and the passive two-axis shoulder joint. Thus, a child does not require a completely new prosthesis every year. Fig. 3A , Fig. 3B , Fig. 3C , Fig. 3D , Fig. 3E , and Fig. 3F depict this girl with her current prosthesis. She is now nine years old and is a very intelligent child. These pictures also reveal the general technique of the pneumatic prosthesis and the prosthetic training involved.

Control of grasp has been improved by using a muscle pressure valve directly connected with the left shoulder instead of a shoulder suction valve (Fig. 3A and Fig. 3B ). From the muscle pressure valve a belt leads across the left shoulder to a double suction valve. Elevation of the shoulder controls hand rotation, and forward motion controls grasp (Fig. 3C ). The elbow joint with automatic lock is controlled by chin action over a four-way pressure valve (Fig. 3D ).

The improved development of the girl's shoulder girdle is largely due to the early application of a prosthesis (Fig. 4A ). For comparative purposes, the picture of an 18-year-old patient is presented (Fig. 4B ). As a small boy he lost both arms at the shoulder joint in an accident involving high voltage current. He did not receive a prosthesis until he was 18 years old. His shoulders were originally normal, but gradually became narrow and sloped because of inactivity. Since the application of a prosthesis to a strong, broad shoulder girdle is easier and promises greater success, the significance of early fitting is emphasized.

Case Two

A 12-year-old girl with bilateral peromelia (hemimelia) is shown in Fig. 5A . Because of her exceptionally long above-elbow stumps, her fitting was both interesting and instructive. From the beginning the possibility of surgical revision to achieve easier application of a prosthesis was rejected. By shortening the stumps, we limit the areas of activity in which a disabled person can function without a prosthesis; a long stump can also provide increased control of the prosthesis.

An outside elbow joint with pneumatic lock was used as depicted in Fig. 5B . You will note that the stump end protrudes from the lower end of the shell and, with the elbow joint flexed, can be utilized for touching. This girl showed remarkable skill in utilizing both stumps, so we provided her with a unilateral prosthesis only. The combination of the prosthesis on one side and the stump on the other side provided her with more function than bilateral prostheses. The prosthesis has an active pneumatic hand with a pneumatic hand-turn joint and a pneumatic elbow lock. The functions are well controlled. The girl attends our school for the physically disabled, wears the (already indispensable) prosthesis all day and uses it for eating, drinking, writing, handicraft and playing.

Case Three

Finally, two interesting unilateral applications of prostheses should be mentioned. The first involves a 10-year-old girl with a left side phocomelia and an elevated scapula (Fig. 6A and Fig. 6B ). Originally, the phocomelic hand hung loosely from the shoulder without noteworthy function. Three years ago it was surgically connected to the clavicle by a splint which has grown tightly into the shoulder, yet provides a functional joint connection. The hand controls the grasping act through a dual pressure valve. The child is very happy with the prosthesis and was able to control the grasping act quite naturally after only a few hours of training.

The sensitivity of the vestigial hand provides the child with a good estimate of the amount of power required to grasp an object. If a phocomelic hand has very limited mobility and power, it can at best be used to actuate the locking valve of the elbow joint. However, it is much more valuable if it can be used to control the grasp function.

Fig. 6B may help to explain the kind of prosthetic provision and training involved in fitting unilateral arm amputees. We provide training in bimanual activities from the early stages. It is a mistake if unilateral upper-extremity amputees are forced to use the prosthesis for activities which they will later perform with the sound arm. As a natural reaction to training of this type, the prosthesis "goes into the closet" soon after the training. However, if the prosthetic hand is trained from the beginning as an assistive device in various areas of activity, the prosthesis is later used remarkably well in the home and, subsequently, in a profession.

Case Four

The illustrations in Fig. 7A and Fig. 7B depict the prosthetic fitting of a 10-year-old boy with a unilateral short above-elbow stump. The prosthesis was first constructed in the conventional manner. It is then possible to substitute a pneumatic hand for a hook or to exchange other parts for certain activities, and also to substitute a pneumatic for a conventional elbow joint.All connective joints are standardized. In this instance, the grasp is controlled by moving the above-elbow stump backward against a valve in the shell. This can be done without interference with the movements controlling the conventional elbow joint.

Conclusions

In the United States, early prosthetic fitting, at first with a passive and later with an active prosthesis, is the customary procedure. Such is not the practice in Germany, where the official bearer of the costs sometimes refuses to authorize the necessary expenditures. This attitude is based on the claim that a child outgrows his prosthesis too quickly and too many expenses are incurred. However, the real facts are that while sockets, adhesive shells and bandages frequently require repair and renewal, the expensive parts of a prosthesis can be utilized for many years.

A child requiring prosthetic service should not lose valuable time because of expense. It may be too late when he is older and about to start a profession. A prosthesis, fitted at an advanced date, often fails or achieves only moderate success. Prosthetic application must begin as early as possible, even if it is difficult to determine the exact type of a prosthesis appropriate for a child's development. A prosthesis should certainly be provided before the child starts school.

The parents of all children with upper-extremity prostheses should receive proper instruction. It is desirable that mothers of children with arm amputations attend the final week of occupational therapy training in writing, eating and playing. The adult who does not observe his child using a prosthesis in the clinic may become discouraged at home by the seemingly complicated technique of an upper-extremity pneumatic prosthesis. The child, however, operates his artificial device without even thinking about the construction of the prosthesis. A child returning home may sometimes prefer the path of least resistance and desire to be fed by his mother, rather than eat by himself with the artificial limb. In view of this, the instruction of the parents and their understanding are essential for the success of an upper-extremity prosthesis fitted in childhood. Prosthetic training is initiated in the clinic, but must be continued in the home. A child may be considered fully adjusted to his prosthesis when it is indispensable for unconstrained play.

We are convinced that the progress already made in providing pneumatic arm prostheses for children must be followed up by the experts in children's care.

(Translated from the German by Maurice M. Schweizer, Ph.D., New York University-Child Prosthetic Studies)