New Hope For The Patient With Severe Upper-Extremity Deficiencies: Externally Powered Prostheses
Maurice Mongeau, M.D.
For many years we have recognized the limited functions provided by conventional prostheses for the amputee with severe upper-extremity deficits. The person with a shoulder disarticulation amputation or other severe upper-extremity loss is quite limited functionally when he is provided with conventional prostheses because of difficulty in activating the different components, especially the terminal devices. The problem becomes even more critical if the high amputations are bilateral.
Since 1962, as an aftermath of the thalidomide tragedy, the number of congenital and acquired amputees referred to our Child Amputee Clinic has increased steadily (our case load is now 243). There has also been an increase in upper-extremity adult amputee referrals. With this growth, a great need for functional improvement of upper-extremity prostheses has become increasingly apparent.
In 1964, the only source of external power available and practically applicable to the amputee was carbon dioxide, which could be used to activate the functional components of upper-extremity prostheses. In the past three years, a total of 24 upper-extremity amputees at our centre have been fitted and trained with 44 prostheses activated by CO2. Twenty of these amputees have been fitted with bilateral CO2 prostheses: three had bilateral amelia, two had unilateral amel-ia and contralateral phocomelia, 14 had bilateral phocomelia (Fig. 1-3 ), and one had a bilateral shoulder disarticulation amputation. Only four amputees have been trained with a unilateral upper-extremity pneumatic prosthesis: one was a unilateral shoulder disarticulation amputee; two were bilateral above-elbow amputees fitted on the dominant side with a pneumatic forearm; and one was a three-year-old quadruple amputee fitted with unilateral CO2 components for the elbow, the forearm, and the terminal device. The average age of this group at the present time is 8.3 years.
In 40 of the 44 CO2 prostheses, the operation of the terminal device (hook), its pronation and supination, and the flexion, extension, and locking of the elbow are powered by small pneumatic pistons controlled by phocomelic fingers, acromion, chin, or traction developed by trunk movements. Power is supplied to the pistons by the release of compressed carbon dioxide. In two prostheses, pronation and supination of the terminal device are the only functions pneumatically activated. In three hybrid prostheses, we have combined a myoelectrically controlled terminal device with a pneumatically controlled elbow and forearm.
At the beginning of 1965, following a visit to Moscow, we at the Rehabilitation Institute of Montreal became interested in the myoelectric prostheses developed in the Soviet Union for forearm amputees. During our clinical trials and experimentation with the Russian hand, the myoelectric prosthesis has been studied and improved in our Research and Prosthetic Departments. We have already fitted and trained 22 upper-extremity amputees with 27 myoelectric prostheses. The present average age of this group of amputees is 39.1 years. Etiological data indicates that 17 patients were traumatic cases, four were amputated following electric burns, and one was amputated as a sequela of an embolism.
For these 22 cases, the levels of amputation were as follows:
We started with forearm amputees (Fig. 4 ) but soon realized that the myoelectric principle could be applied with very interesting results to severely handicapped upper-extremity amputees, such as shoulder disarticulation or forequarter cases, where conventional prostheses provide little function and are quite often discarded by the amputee. In the past ten months, we have fitted and trained two unilateral forequarter amputees (Fig. 5 and 6 ), two unilateral shoulder disarticulees, and one bilateral shoulder disarticulation amputee, by using signals from trunk muscles (trapezius, rhomboids, dorsalis major, pectoralis major, and others) to activate the artificial hand. In three of these five cases, only the terminal device (Russian hand) was activated by myoelectric control, the remainder of the prosthesis being conventional.
In two amputees, including a bilateral shoulder disarticulation case (Fig. 7 and Fig. 8 ), we have combined two different principles of external power in the same prosthesis - the so-called hybrid prosthesis. This hybrid prosthesis incorporates (1) the application of myoelectric control by using muscles of the trunk to activate the terminal device, and (2) the application of pneumatic control by using carbon dioxide to activate the forearm and elbow.
With the experience acquired in the use of carbon dioxide in upper-extremity prostheses and also with the results obtained from myoelectric control in the use of the Russian hand, we firmly believe that it is now possible to solve some of the problems of severely afflicted upper-extremity amputees by giving them better function, more independence, and better appearance.
There is no doubt that in the coming years more demands will arise for practical and functional external power prostheses for high-level upper-extremity amputees. In order to improve the upper-extremity prostheses we now have, we surely need more basic research and more cooperation among engineers, physicians, and prosthetists who deal with amputees. We particularly need more and better clinical trials and clinical research on the sophisticated external power systems that now exist as laboratory models.
Maurice Mongeau, M.D. is the Clinic Chief of the Children's Amputee Clinic Rehabilitation Institute of Montreal Montreal, Quebec