An Experience With Externally Powered Prostheses For Children

J. Leonard Goldner, M.D. Bert R. Titus, C.P.O.


The Duke Orthopaedic Juvenile Amputee Clinic team continues to have difficulty in managing patients with congenital upper-extremity amelia and phocomelia, particularly when these conditions occur bilaterally. Historically, the problem has been insoluble from the time we opened our Clinic in 1955. We have equipped and trained several patients with bilateral amelia, first with one unit and then another, in the conventional way. In each instance the initial reception and accommodation by the patient was excellent, but eventually the prostheses have been discarded because of intolerance to increased body heat, slowness in performing the activities of daily living, distortion of total body image, appearance, emotional changes associated with changing age, and continued dependence on the feet.

After 12 years of intermittent trial, none of our bilateral amelic patients is wearing a prosthesis, and only a few with unilateral phocomelia continue to wear the prosthesis part time. Something else was needed, and a new approach had to be initiated in order to solve this problem if, in fact, the problem needed solving. Philosophically, the attitude of some patients with bilateral amelia might well be the answer to our efforts. For example, a 40-year-old California housewife, in spite of her handicap of bilateral amelia, had raised two children to the teen-age level without outside help and without the aid of prostheses. She is emphatic in her belief that a prosthesis would have been a hindrance to her performance.

One of our patients with bilateral amelia visited this woman in California, and both the child and its mother lost their sense of frustration and guilt associated with discarding the prosthesis that the child had worn intermittently for five years. The time, effort, and expense were not wasted; both the family and the patient had been given a choice.

Our experience may be unique, and other clinics may be having more success than we are. If so, we would like to learn what they are doing. We are not so interested in being able to fit and train patients with these devices as we are in their application to daily activities-whether the patient can perform more easily with prostheses than without, and his emotional acceptance of the devices over a period of six to eight years.

It has seemed to us that if the problems of these severely handicapped children are to be solved prosthetically, external rather than body sources of power are required. We have therefore experimented with both electrically and pneumatically powered prostheses. Our experiences with these devices are presented in the discussion which follows:

Case 1 (T.J.)

Two years ago, a patient with bilateral upper-extremity amelia came under our care. As an infant she had congenital dislocation of the hip, but at 18 months she was ambulatory, with a shoe lift on the involved side and a slight limp. She was adept at using her feet for manipulation and grasp. The hip condition was an unusual one, and because of the risk of diminishing her range of hip rotation by open reduction or similar treatment, the femur was allowed to remain dislocated. She followed the usual pattern of adapting to the demands of her daily activities by using her feet, but she was interested in and willing to try a prosthesis. We, of course, were ready to assist her. Early application would permit maximum development of both upper and lower extremities, would provide her with a choice of using the prosthesis or her feet, and would give us information about current developments.

In 1965 we secured from New York University an experimental electric feeding arm which had been made available for field testing. Our prosthetist, Mr. Bert Titus, and a physical therapist at the children's hospital in Durham worked diligently to provide this two-year-old with a functional extremity. She cooperated better than most children of her age, in that she accepted the prosthesis for use at mealtime, and tried to use it for other limited and light activities .

The unit was given a fair trial, but certain inherent deficiencies quickly became apparent. The screw in the shoulder joint which holds the wedges involved in humeral-section-to-socket alignment became loose on several occasions and had to be tightened. The microswitch wiring broke a number of times and needed repair and strengthening. Slippage of the socket occurred frequently, interfering with the child's ability to contact the fore and aft switches, with resulting frustration.

Elbow joint function was moderately smooth. However, because the humeral section was so long, the forearm had to be reduced to minimal size, with a resulting alteration in the lever system and loss of force. The small output, compared with the large input, resulted in low efficiency and limited function.

The power pack gave continuous difficulty because of its low energy production. The pack was sent to various repair areas and worked on by knowledgeable individuals, but only minimal improvement was obtained.

The wrist unit became loose after the prosthesis was worn for a few hours. The terminal device needed a thumb extension to anchor a spoon, a pencil, and similar objects, and its flat surfaces were too wide for many of a small child's activities. The terminal device also limited visibility of small objects.

In spite of these mechanical problems, the patient continued to use the prosthesis each day and demonstrated that persistence and encouragement could surmount many seemingly insurmountable obstacles. Fig. 1-3 show the child when she was about two and a half years old without the prosthesis, using her feet for play and action. Fig. 4-6 show her attempting to draw and eat with the electric feeding arm. However, interruption and failure of the power supply resulted in frequent periods of disuse.

The child regularly used her right foot and the left upper-extremity prosthesis to hold and pick up objects. Thus, although she seldom used the terminal device alone, she did find it an advantage in supplementing the actions of her feet. The arm was modified by the provision of stronger springs for the motor mounting in order to eliminate motor movement and allow more direct power drive. The nylon fitted sleeves were replaced by sleeves of hard aluminum to diminish the power necessary to flex and extend the forearm. The original terminal device was replaced by a Dorrance 10X hook in order to improve function.

Currently the power pack is under observation and some experimentation by two electrical engineers. The shoulder joint has been reworked, and the plastic socket is being altered in order to improve the shoulder contacts.

In order not to lose our subject and to maintain some degree of continuity, we contacted Dr. Edward A. Kiessling, a research engineer who is working on a pneumatic power system for the amelic patient under the sponsorship of the Children's Bureau. The success of his work was evident shortly after he came to Durham and assisted Mr. Titus in providing the patient with a new prosthesis. Within five days, a light, shell-type, well-aerated plastic socket, strong enough to support the power pack, the arm, and the forearm, was constructed. The smooth functioning of the activating mechanism, the terminal device, and the joints was obvious the first time the patient tried on the prosthesis. She was excited and interested, and the new arm has been worn several hours each day. The child has learned to use it to feed herself a complete meal, for certain play activities, and for drawing and printing. A second prosthesis is now being planned and will be applied in October 1967.

Fig. 7-9 show the patient with the carbon dioxide cylinder that provides power for the prosthesis and allows her to use the terminal device and elbow joint with greater ease and strength than before.

It is true that certain disadvantages exist, such as noise, the need for frequent refilling of the CO2 cylinder, slippage of the plastic socket on the wet skin, and the array of tubules. Nevertheless, the efficiency and strength of the new arm have more than compensated for the inconvenience.

In the near future we plan to fit this girl with a three-function prosthesis which will give her elbow flexion and extension, terminal device flexion and extension, and terminal device supination and pronation.

Case 2 (R.L.)

We have a second patient, now 12 years old, with a right shoulder disarticulation amputation secondary to trauma, and a very short below-elbow amputation on the opposite side. She is using a conventional prosthesis for the short below-elbow stump (Fig. 10 ), but the shoulder disarticulation prosthesis is powered by carbon dioxide (Fig. 11-13 ). Within a few days after fitting she was making more assistive use of this prosthesis than she had of her conventional arm over the past two or three years.

The patient has continued to wear her conventional below-elbow prosthesis with a preflexed forearm on the left side. This, of course, is her dominant "hand," and the pneumatic arm is therefore not essential. Consequently she has not developed the skill of the child with bilateral amelia.

Our enthusiasm for external power is not boundless. We recognize the limitations of both these prostheses, but realize that experimental effort must continue on a broad scale, even though the number of amelic patients is not large. The need is obvious, and the scientific personnel and materials are certainly available.

Obviously both the electric arm and the carbon dioxide prosthesis will be improved during the next couple of years. Concentrated effort should be directed toward making both units lightweight and efficient. We shall continue to work with both and hope to contribute worthwhile innovations.

J. Leonard Goldner, M.D. is the Professor of Orthopaedic Surgery and Chief of Orthopaedic-Amputee Clinics Duke University Medical Center Durham, North Carolina

Bert R. Titus, C.P.O. is the Director of Prosthetics and Orthotics Duke University Medical Center Durham, North Carolina