Biomedical Engineering Program Development

George T. Aitken, M.D.

An after-dinner address given at the annual meeting of the Division of Engineering of the National Research Council, March 11, 1968.

Mr. President, Division Members, and Guests:

I am indeed flattered to have been asked to appear here this evening, but frankly I am concerned as to whether I will be able to present a proper message for a group such as this.

You gentlemen represent a group of scientists whose backgrounds are highly expert ones in a variety of engineering fields. My background is medicine, specifically the private practice of medicine as an orthopaedic surgeon. An area of special interest within orthopaedics has been the rehabilitation of children with acquired amputations and congenital limb deficiencies. Because of this interest, I have been associated, initially peripherally and recently intimately, with the activities of the Committee on Prosthetics Research and Development for a period of 15 years. It has been my opportunity, therefore, to be fully acquainted with the development and progress of this particular biomedical engineering program, and it is about this that I would like to speak.

Meaning of Biomedical Engineering

Before discussing the specifics, it might be well to review the term "Biomedical Engineering." I am unable to find a good definition. So, in order to clarify this presentation, it may be well to present my concept of the meaning of this term.

Biomedical engineering is a cooperative effort by a multidisciplinary group which includes representatives from the fields of biology, medicine, and engineering. The activities of such a group are stimulated by recognized but unmet needs of patients: Basically, we have three types of patients. First, we have the intact patient-a patient without disease or deformity. Second, we have a patient with a disease. Third, we have a patient who has a disability due to a loss of function or an anatomical loss of a portion of the body. These three types of patients stimulate us to do different types of multidisciplinary research.

The intact patient, or the one without disease or deformity, stimulates us to do biomedical engineering research and development only if this patient is required to exist and function for varying periods of time in an environment that is hostile to human life. The development of our current space program has depended in part on biomedical engineering research designed to modify the environment so that highly selected intact individuals may live and function in an otherwise hostile environment.

The second group of patients, those with disease, stimulates a different type of biomedical engineering endeavor. These are patients who require the provision of temporary artificial organ function in order to permit surgical repair of their own organs; or transplantation of organs; or replacement of malfunctioning internal parts with mechanical devices. The heart-lung machine, the artificial kidney, the renal dialysis unit, and the cardiac pacemaker are all examples of biomedical applications in this area.

The third group of patients, those with a loss of function or an anatomical loss of a portion of the body, stimulates yet a different type of biomedical engineering activity. These are people whose lives are generally not in jeopardy, but whose functional level is materially reduced. It is not a question here of temporarily altering their environment to permit normal function, nor is it one of temporarily or permanently replacing a damaged part essential to life. Here, it is the development of a permanent replacement that will permit optimal functioning in a normal environment. Simple examples of such problems are glasses for those with visual defects, and dentures for those who have lost their teeth. More complicated examples are the development of upper- and lower-limb prostheses for partial or complete loss of upper and lower limbs; the most complicated example (at least to date) is the development of visual prostheses for the totally blind-a goal as yet unattained.

This, like all other definitions or classifications, is open to discussion, and I am certain that there are many defects in such a summarization. For the purposes of tonight's discussion, however, it will at least identify the area that I wish to discuss. My remarks will be limited to the Group III" type patient, and specifically to the Group III-type patient with anatomical loss, complete or incomplete, of one or more limbs.

The Patient With an Amputation

Amputations are as old as the history of medicine. Each succeeding war has produced a marked increase in the numbers. As improvements in medicine have made it possible to remove limbs, prevent infections and obtain healing of the stump, increasing numbers of amputees have survived to require support or rehabilitation. The Industrial Revolution introduced additional hazards to limbs, and our modern transportation equipment has introduced another cause of limb losses. With us always have been the congenital malformations that are manifested by partial or complete absence of limbs. This problem has stimulated a wide variety of people to attempt a kind of biomedical engineering. Such efforts were initially very crude, and they were developed by the artisans who were skilled in wood and metal fabrication techniques. So, in medieval times the armorer was the limb-maker. Later, guild-type craftsmen became specialized in the techniques of making artificial limbs. The design of these limbs was basically a reproduction of the form of the lost part, with an attempt made in some instances to reproduce the lost function.

It was not until the end of World War II that a truly multidisciplinary approach to the problem was established in an effort to develop improved prosthetic services.

Prior to this time, the surgeon was concerned with the amputation only. The prosthetist was responsible for the fabrication, fit, and alignment of the prosthesis, and in many instances for the design of component parts also. Paramedical personnel were only minimally involved in the post-amputation training of patients in the use of prostheses.

Under the aegis of the Committee on Artificial Limbs, the team approach was established. The physician was encouraged to be involved not only in the surgery of amputations, but also, on the basis of his knowledge of kinesiology and his ability to diagnose functional loss, to become interested in clearly defining the essential functional regain that was desirable in the artificial limb.

The engineer was encouraged to attempt to translate biomechanical losses into design criteria for well-engineered, mechanical replacement components. Also, he was encouraged to utilize his special knowledge in the area of new materials to encourage prosthetists to take advantage of the wide variety of lightweight, easily formed, structurally sound plastics, resins, and metals that were becoming industrially available at a rapidly accelerating rate.

New fitting and alignment techniques developed out of the fundamental studies done by physicians and engineers in the areas of upper-and lower-limb function.

Using modern instrumentation, the whole field of "how man walks" was reviewed. As a result, there developed a new body of basic research data that could be utilized to establish design, fit and alignment criteria.

This program also developed a generous body of additional basic research information, including data from time-motion studies of upper-limb function and the metabolic cost of prosthesis wearing.

From this program evolved a wide variety of new, well-designed components and fitting techniques for upper- and lower-limb prostheses, including new fabrication techniques, plastic laminate sockets, and adjustable legs for alignment. Transfer jigs to reproduce ideal alignment in finished legs were developed also.

Unfortunately, this very valuable knowledge was initially available only in research laboratories, and it involved the utilization of handmade components.

Education Necessary

Since the whole program was stimulated by the needs of a large body of patients, a method to get the results of research and development on the patient needed to be found.

Education was considered to be the solution. Schools of prosthetic education were established. In these schools, physicians, prosthetists, and therapists were trained by experts to prescribe, fit and align prostheses that incorporated all of the available new concepts and components, and to train patients in their use.

Such a program stimulated demand for these improved items and service. This demand encouraged industry to make the results of research and development commercially available.

A full circle had been made. A patient with a functional loss was evaluated, and the need for better care was recognized. By a multi-disciplinary approach a solution was found, and by education of those involved in patient care the benefits of this biomedical engineering research and development were returned to the patient.

There are a multitude of examples of the results of this program, particularly in the adult area. By means of joints and rubber bumpers, early prosthetic feet attempted to simulate the dorsi- and plantar-flexion motions of the ankle and the inversion and eversion function of the subtalar joint. When the functional characteristics of the ankle were described by the clinician, the engineer was capable of producing a component, the SACH (solid-ankle cushion-heel) foot that, without any moving parts, would duplicate adequately the ranges of dorsi- and plantar flexion and inversion and eversion that were necessary for good prosthetic gait.

There are many other examples, but I believe that I can more adequately highlight this program by talking about the area that is my particular interest.

The Child Amputee

Each year a number of children are born without upper extremities. These children are condemned to live dependent upon foot function as a substitute for arm function unless one can supply them with adequate upper-extremity prostheses. A multidisciplinary approach to this problem is currently in progress in several laboratories. The physician has been asked to translate the anatomical loss into functional loss terms so that the engineer may clearly understand the specifics of the replacement problem; design criteria can be developed, new designs translated into prototypes, and the prototypes studied in clinical applications to determine their efficacy. Eventually, when a reasonable prototype has been developed, adequate numbers of the prototype must be provided by one mechanism or another. Physicians, prosthetists, and allied health personnel must then be educated so that patients who could be benefited by these prostheses are fitted with them and trained in their use.

Patient-Related Research Essential

Certain types of research are not related to specific needs other than those of increasing knowledge and developing new concepts.

Biomedical engineering research must, in my opinion, remain constantly related to the patients' needs. It is from the patient that the research stimulus arises; it is only by evaluating the results of research on the patient that a determination of the validity of the results can be made. Lastly, and possibly most importantly, the results of successful research must be made as generally available to patients as their needs require. In the case of large-volume items such as prosthetic feet, our private enterprise system can profitably fill the demands. In the case of low-volume items such as externally powered arms for the juvenile amelic, a mechanism other than private enterprise will probably have to be developed. Whether this mechanism is private funding; local, state, or federal governmental funding; or some type of inclusion in established governmental health programs is not clearly established.

The important feature is that, unless a recognition of this need for transition from research and development to general patient application is an integral part of biomechanical engineering planning, the results of such research and development will fail to justify their funding or their accomplishments.

George T. Aitken, M.D. is the Medical Co-Director of the Area Child Amputee Center Grand Rapids, Michigan