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Hand and finger prostheses
REVIEW ARTICLE
Hand and finger prostheses Robert W. Beasley, M.D., F.A.C.S., New York, N.Y.
T
here have been rapid changes within our society and an astounding shift in the composition of the work force from labor to professional and service industries. Few workers are now engaged in heavy labor which is being progressively done by machines. According to the last census, the majority of jobs today involve people dealing with people; only 18% of the work force in the United States is engaged in manual labor. This, in tum, has changed the prosthetic needs of patients. For many patients, attention to esthetic considerations is a greater need than improving prehension. It is interesting that what the patient perceives as a stigma may also be interpreted as such by those around him. Also, there is almost no relationship between the actual physical loss and the psychological response or total impact of the loss. One patient with loss of a finger may have more difficulty adjusting than another patient with a major loss. Today we must view function in the total sense of how one functions in society, not merely as prehension. Logical conclusions can be reached only by comparison of all alternatives .' Therefore, the surgeon who is charged with primary responsibility for guiding the patient must be well versed not only in the surgical and reconstructive possibilities but also in the prosthetic potentials. Errors in initial judgment are not only costly but often result in irreversible changes which, ifunwise, permanently compromise the situation . By no means do all amputees need prostheses. We must listen to our patients, accurately determine their real needs , and discard preconceived and stereotyped ideas . For many patients an esthetic prosthesis may offer the greatest help , either alone or in combination with surgical repairs . Incorporation of the prosthesis into a master plan early on is best. The surgeon should not "go as far as he From the New York University and Bellevue Hospital Hand Services. New York, N.Y. This article was accepted for publication before July I, 1986. No conflict-of-interest statement was requested from the authors . Reprint requests: Robert W. Beasley, M.D., 310 E. 30th. St. , New York, NY 10016.
144
THE JOURNAL OF HAND SURGERY
can" and then send the patient for consideration of prosthetic fitting. Leaving parts optimal for prosthetic fitting should be viewed as an important reconstructive procedure, performed with skill and thorough knowledge of the requirements (Fig. I). Recognizing that esthetic considerations of the hands are very important, we need to be aware of how our system of visual perception works. In casual observations we essentially scan the scene and perceive only that which we are expecting to see, making a critical analysis of the observed only if there is some unexpected factor causing us to do SO.2 A hand with three normal fingers and a thumb, for example, attracts less attention than a hand with three normal fingers, a thumb, and a deformed finger. The ability to accomplish ordinary tasks in the usual and expected manner is often as important esthetically as the number of parts, color, form, etc. which the prosthetic artist can today reproduce with remarkable likeness (Figs. 1,2, and 3) except when the parts are truly grotesque. It is important that the prescribed prosthesis not obstruct existing physical capability, or the loss may be made more conspicuous. While the psychological response has little quantitative relation to the actual physical loss, it is obviously a major consideration in successful treatment. Fortunately, bilateral total hand loss is extremely rare since it results in such a severe physical handicap as to overshadow almost all other considerations. With unilateral hand loss, and with all partial hand amputations, there is a tremendous tendency to overestimate the physical impairment while neglecting the total impact. A person can accomplish about 90% of the activities of daily living (ADL) with one normal hand and manage the rest with a little extra effort. Achild with unilateral agenesis is unaware of any problem until the age of social consciousness. His methods of doing things will be a little different, but he gets the job done. All, however, suffer from a sense of stigma, and for many this is the paramount problem. Experience with many patients who have been fitted with prostheses has led to a new understanding of the role of sensibility in hand function. While always desirable and important for position sense, good sensi-
Vol. 12A, No.1 January 1987
Hand and finger prostheses
145
Fig. 1. A, Partial hand agenesis. B, The fine. silent, soft. lightweight esthetic prosthesis provides adjustable fingers against which the short thumb extended by the prosthesis can oppose. Nearnormal appearance eliminates the stigma, real or imaginary. C, The exquisite inlaid fingernails, copied faithfully in detail from the normal hand. Fig. 2. A, Total left hand loss. B, The esthetic prosthesis is a passively adjustable "vise", which loaded by the normal hand holds objects to be manipulated by that hand. C, Tying a scarf and similar simple but useful manipulations are possible with the passively-adjustable esthetic prosthesis.
bility is, in fact, not essential for effective power grasp or most percussion activities. In contrast, it must be essentially normal for effective small object manipulations. Consider how the patient with carpal tunnel syndrome has difficulty even with simple buttons. Recognizing this, it becomes apparent that the goals of major reconstructions, such as toe-to-hand transfers in which nerves are cut and sutured, or prosthetic devices
are almost the same. Usually the basic goal is to restore a pinch or vise mechanism that works effectively without normal sensibility. Neither can restore the ability needed for precision manipUlations. Contrary to most teaching, a precisely fitting finger prosthesis functions superbly as it transmits both pressure and position sense needed for automatic control with such activities as typing (Fig. 1). While the objectives of reconstruction
146
Beasley
The Journal of HAND SURGERY
Fig. 3. A, The shortest finger for which secure single digit prosthetic fitting is possible is about % inch. B, Long finger prosthesis, with ring proximally at juncture with skin. C, The new Bio-
Chromatic coloring process is a technological breakthrough, which results in unprecedented color matching and unique likeness, even for those with deeply pigmented skin. (Bio-Chromatic, American Hand Prosthetics, Inc., New York, N.Y. Photographs were provided by American Hand Prosthetics, Inc., New York, N.Y.)
and prosthetic fitting are similar, very often the prostheses will have a major esthetic advantage, which to many patients is the prime consideration. Sometimes a combination of surgical repairs with prosthetic fitting gives the best result. Prosthetic devices for the hand should be classified simply as total or partial hand prostheses . In tum, total prostheses can be divided into actively or passively adjustable types. In either case, they are no more than simple vise mechanisms, which are effective only for holding items to be manipulated with the normal hand (Figs. 2 and 3). The body-cable-powered, electric, or other actively adjustable devices provide more clamping power but do not have significant advantages over passively adjustable prostheses. The advantage must be weighed against their appearance, their clublike feeling on contact, maintenance requirements, and the high initial and maintenance cost of motorized units. A major problem with actively adjustable or so-called "functional" hand prostheses is that they are all "second-thought" devices. Nothing happens automatically, as with a normal hand. The desired clamping or releasing results from individually initiated commands that are transmitted through intermediaries, such as muscle of totally unrelated action in a myoelectric system. Farmers and those still engaged in heavy labor benefit from body-powered or externally powered car-
rier-tool type prostheses for specific tasks; at other times they usually find the advantages of actively moving units too small to offset the disadvantages. Most unilateral total-hand amputees today, not involved in labor, are finding their needs better met with the lifelike, lightweight, but passively adjustable hand prosthesis, which strikes a good balance between light-object-holding capacity and socially acceptable appearance (Fig. 2). Partial hand prostheses are all passive, but in general are even more successful than the total hand prostheses in improving mechanical function and at times even benefit the bilaterally injured. They restore length or opposing parts, enhancing physical capability. Such prostheses may be simple palettes, but more often today a lifelike prosthesis is desired to simultaneously provide prehensile improvement and esthetic restoration. Partial hand prostheses are even more difficult to design and are more technically demanding in fabrication than the total hand ones, but the results often are striking (Figs. 1 and 3). Individual finger or thumb prostheses are an increasingly important group of the partial hand type. The degree of function they restore is often unexpected and remarkable. Good esthetic results for digital prostheses require even greater perfection of details than a total hand, as they have a normal digit alongside for visual comparison. Individual finger prostheses are better than a glove with fingers, but the latter will be necessary
Vol. 12A, No . 1 January 1987
when an amputated digit extends less than about 15 mm beyond the interdigital web or fixation will be insecure. Also, a finger cannot have good presentation without a fingernail, a problem for which there is as yet no satisfactory surgical solution. The fingernails of the modem prostheses can match the normal almost perfectly (Fig. 3, C). Aside from appropriate patient selection and custom design, there are two conditions essential to satisfactory use of passively adjustable prostheses. First, construction must be to the highest standards, with meticulous attention to all details. If it is not a near replica of the normal, the prosthesis may serve only as a focal point of morbid curiosity, exactly contrary to its intended purpose. Second, reliable and prompt repair services must be available. There have been changes in our society and in the
Hand and finger prostheses
147
composition of the work force ; these make the stigma of agenesis or acquired hand deformities a real socioeconomic handicap. Relief from the stigma, while simultaneously improving physical capability, is often achieved with fine esthetic hand prostheses. The hand surgeon must be knowledgeable about prosthetics and consider them in his early comprehensive planning. REFERENCES 1. Brown PW: The rational selection of treatment for upper extremity amputations. Orthop Clin North Am 12:843-8, 1981 2. Beasley RW: Cosmetic considerations in surgery of the hand. In Tubiana R, editor: The hand, vol 2, Philadelphia, 1985, WB Saunders Co, pp 96-103
Hand and finger prostheses Robert W. Beasley, M.D., F.A.C.S., New York, N.Y.
T
here have been rapid changes within our society and an astounding shift in the composition of the work force from labor to professional and service industries. Few workers are now engaged in heavy labor which is being progressively done by machines. According to the last census, the majority of jobs today involve people dealing with people; only 18% of the work force in the United States is engaged in manual labor. This, in tum, has changed the prosthetic needs of patients. For many patients, attention to esthetic considerations is a greater need than improving prehension. It is interesting that what the patient perceives as a stigma may also be interpreted as such by those around him. Also, there is almost no relationship between the actual physical loss and the psychological response or total impact of the loss. One patient with loss of a finger may have more difficulty adjusting than another patient with a major loss. Today we must view function in the total sense of how one functions in society, not merely as prehension. Logical conclusions can be reached only by comparison of all alternatives .' Therefore, the surgeon who is charged with primary responsibility for guiding the patient must be well versed not only in the surgical and reconstructive possibilities but also in the prosthetic potentials. Errors in initial judgment are not only costly but often result in irreversible changes which, ifunwise, permanently compromise the situation . By no means do all amputees need prostheses. We must listen to our patients, accurately determine their real needs , and discard preconceived and stereotyped ideas . For many patients an esthetic prosthesis may offer the greatest help , either alone or in combination with surgical repairs . Incorporation of the prosthesis into a master plan early on is best. The surgeon should not "go as far as he From the New York University and Bellevue Hospital Hand Services. New York, N.Y. This article was accepted for publication before July I, 1986. No conflict-of-interest statement was requested from the authors . Reprint requests: Robert W. Beasley, M.D., 310 E. 30th. St. , New York, NY 10016.
144
THE JOURNAL OF HAND SURGERY
can" and then send the patient for consideration of prosthetic fitting. Leaving parts optimal for prosthetic fitting should be viewed as an important reconstructive procedure, performed with skill and thorough knowledge of the requirements (Fig. I). Recognizing that esthetic considerations of the hands are very important, we need to be aware of how our system of visual perception works. In casual observations we essentially scan the scene and perceive only that which we are expecting to see, making a critical analysis of the observed only if there is some unexpected factor causing us to do SO.2 A hand with three normal fingers and a thumb, for example, attracts less attention than a hand with three normal fingers, a thumb, and a deformed finger. The ability to accomplish ordinary tasks in the usual and expected manner is often as important esthetically as the number of parts, color, form, etc. which the prosthetic artist can today reproduce with remarkable likeness (Figs. 1,2, and 3) except when the parts are truly grotesque. It is important that the prescribed prosthesis not obstruct existing physical capability, or the loss may be made more conspicuous. While the psychological response has little quantitative relation to the actual physical loss, it is obviously a major consideration in successful treatment. Fortunately, bilateral total hand loss is extremely rare since it results in such a severe physical handicap as to overshadow almost all other considerations. With unilateral hand loss, and with all partial hand amputations, there is a tremendous tendency to overestimate the physical impairment while neglecting the total impact. A person can accomplish about 90% of the activities of daily living (ADL) with one normal hand and manage the rest with a little extra effort. Achild with unilateral agenesis is unaware of any problem until the age of social consciousness. His methods of doing things will be a little different, but he gets the job done. All, however, suffer from a sense of stigma, and for many this is the paramount problem. Experience with many patients who have been fitted with prostheses has led to a new understanding of the role of sensibility in hand function. While always desirable and important for position sense, good sensi-
Vol. 12A, No.1 January 1987
Hand and finger prostheses
145
Fig. 1. A, Partial hand agenesis. B, The fine. silent, soft. lightweight esthetic prosthesis provides adjustable fingers against which the short thumb extended by the prosthesis can oppose. Nearnormal appearance eliminates the stigma, real or imaginary. C, The exquisite inlaid fingernails, copied faithfully in detail from the normal hand. Fig. 2. A, Total left hand loss. B, The esthetic prosthesis is a passively adjustable "vise", which loaded by the normal hand holds objects to be manipulated by that hand. C, Tying a scarf and similar simple but useful manipulations are possible with the passively-adjustable esthetic prosthesis.
bility is, in fact, not essential for effective power grasp or most percussion activities. In contrast, it must be essentially normal for effective small object manipulations. Consider how the patient with carpal tunnel syndrome has difficulty even with simple buttons. Recognizing this, it becomes apparent that the goals of major reconstructions, such as toe-to-hand transfers in which nerves are cut and sutured, or prosthetic devices
are almost the same. Usually the basic goal is to restore a pinch or vise mechanism that works effectively without normal sensibility. Neither can restore the ability needed for precision manipUlations. Contrary to most teaching, a precisely fitting finger prosthesis functions superbly as it transmits both pressure and position sense needed for automatic control with such activities as typing (Fig. 1). While the objectives of reconstruction
146
Beasley
The Journal of HAND SURGERY
Fig. 3. A, The shortest finger for which secure single digit prosthetic fitting is possible is about % inch. B, Long finger prosthesis, with ring proximally at juncture with skin. C, The new Bio-
Chromatic coloring process is a technological breakthrough, which results in unprecedented color matching and unique likeness, even for those with deeply pigmented skin. (Bio-Chromatic, American Hand Prosthetics, Inc., New York, N.Y. Photographs were provided by American Hand Prosthetics, Inc., New York, N.Y.)
and prosthetic fitting are similar, very often the prostheses will have a major esthetic advantage, which to many patients is the prime consideration. Sometimes a combination of surgical repairs with prosthetic fitting gives the best result. Prosthetic devices for the hand should be classified simply as total or partial hand prostheses . In tum, total prostheses can be divided into actively or passively adjustable types. In either case, they are no more than simple vise mechanisms, which are effective only for holding items to be manipulated with the normal hand (Figs. 2 and 3). The body-cable-powered, electric, or other actively adjustable devices provide more clamping power but do not have significant advantages over passively adjustable prostheses. The advantage must be weighed against their appearance, their clublike feeling on contact, maintenance requirements, and the high initial and maintenance cost of motorized units. A major problem with actively adjustable or so-called "functional" hand prostheses is that they are all "second-thought" devices. Nothing happens automatically, as with a normal hand. The desired clamping or releasing results from individually initiated commands that are transmitted through intermediaries, such as muscle of totally unrelated action in a myoelectric system. Farmers and those still engaged in heavy labor benefit from body-powered or externally powered car-
rier-tool type prostheses for specific tasks; at other times they usually find the advantages of actively moving units too small to offset the disadvantages. Most unilateral total-hand amputees today, not involved in labor, are finding their needs better met with the lifelike, lightweight, but passively adjustable hand prosthesis, which strikes a good balance between light-object-holding capacity and socially acceptable appearance (Fig. 2). Partial hand prostheses are all passive, but in general are even more successful than the total hand prostheses in improving mechanical function and at times even benefit the bilaterally injured. They restore length or opposing parts, enhancing physical capability. Such prostheses may be simple palettes, but more often today a lifelike prosthesis is desired to simultaneously provide prehensile improvement and esthetic restoration. Partial hand prostheses are even more difficult to design and are more technically demanding in fabrication than the total hand ones, but the results often are striking (Figs. 1 and 3). Individual finger or thumb prostheses are an increasingly important group of the partial hand type. The degree of function they restore is often unexpected and remarkable. Good esthetic results for digital prostheses require even greater perfection of details than a total hand, as they have a normal digit alongside for visual comparison. Individual finger prostheses are better than a glove with fingers, but the latter will be necessary
Vol. 12A, No . 1 January 1987
when an amputated digit extends less than about 15 mm beyond the interdigital web or fixation will be insecure. Also, a finger cannot have good presentation without a fingernail, a problem for which there is as yet no satisfactory surgical solution. The fingernails of the modem prostheses can match the normal almost perfectly (Fig. 3, C). Aside from appropriate patient selection and custom design, there are two conditions essential to satisfactory use of passively adjustable prostheses. First, construction must be to the highest standards, with meticulous attention to all details. If it is not a near replica of the normal, the prosthesis may serve only as a focal point of morbid curiosity, exactly contrary to its intended purpose. Second, reliable and prompt repair services must be available. There have been changes in our society and in the
Hand and finger prostheses
147
composition of the work force ; these make the stigma of agenesis or acquired hand deformities a real socioeconomic handicap. Relief from the stigma, while simultaneously improving physical capability, is often achieved with fine esthetic hand prostheses. The hand surgeon must be knowledgeable about prosthetics and consider them in his early comprehensive planning. REFERENCES 1. Brown PW: The rational selection of treatment for upper extremity amputations. Orthop Clin North Am 12:843-8, 1981 2. Beasley RW: Cosmetic considerations in surgery of the hand. In Tubiana R, editor: The hand, vol 2, Philadelphia, 1985, WB Saunders Co, pp 96-103