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Myoelectric and Body-Powered Upper-Limb Prostheses: The Users’ Perspective

Davis, Carrie MAOL; St. Onge, Mike AA

Journal of Prosthetics and Orthotics: October 2017 - Volume 29 - Issue 4S - p P30–P34
doi: 10.1097/JPO.0000000000000155
Proceedings
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There are a number of considerations that clinicians weigh when guiding patients through the decision-making processes associated with upper-limb prosthetic rehabilitation. While clinical guidance is essential to such decisions, especially for an individual's first prosthesis, many patients benefit from peer mentoring and interaction. The opportunity to speak to someone who has experienced what they are going through can be extremely valuable and appreciated. Thoughtful clinicians have also benefited from years of listening to the perspectives of their patient clientele. The intent of this article is to present two users' perspectives that canvass some of the various considerations associated with congenital deficiency versus acquired limb amputation, unilateral versus bilateral limb absence, and the perceived benefits associated with body-powered and externally powered systems.

CARRIE DAVIS, MAOL, is affiliated with Patient Experience, Sales and Marketing Division of Hanger Clinic, Hanger Inc., Austin, Texas.

MIKE ST. ONGE, AA, is a retired aircraft mechanic from The Boeing Company, Long Beach, California.

Disclosure: The authors declare no conflict of interest.

Correspondence to: Carrie Davis, MAOL, 4021 E. Windsong Avenue, Spokane, WA 99223; email: cdavis@hanger.com

In compiling the contents of the proceedings, there was agreement from the conference attendees that the perspectives of the end user should be represented. However, this decision is not without its pitfalls, as the individual needs, preferences, and resources of each patient are unique to that individual. Thus, the opinions and experiences of a single end user can never adequately represent the perspective of the entire population and could unintentionally skew content away from the state of the science toward the preferences of a single individual. Indeed, given the wide variety of needs, preferences, and resources in clinical care, it is beyond the scope and capacity of these conference proceedings to comprehensively cover the myriad of end user perspectives that might be found in clinical care.

However, two ideal end users were identified who were able to provide a general overview of common experiences of end users. Carrie Davis describes her perspective as an end user with a congenital unilateral transradial limb deficiency who grew up using body-powered (BP) systems and now prefers an externally powered prosthesis. In turn, Mike St. Onge describes his perspective as an end user with acquired bilateral amputations at the transradial and through-elbow level, respectively. Mike currently chooses to use a BP device on the transradial limb and prefers no prosthesis on his arm with the through-elbow amputation. Thus, these two commentaries provide a collective user's perspective that, if not comprehensive, is rather broad encompassing considerations germane to congenital and acquired limb deficiency, unilateral and bilateral deficits and prosthetic preferences towards body power, external power, and the choice of no prosthesis.

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USER’S PERSPECTIVE: EXTERNAL POWER

CARRIE DAVIS

I was born in 1971, long before ultrasound technology at the 20-week gestational mark was being used. Not only was it a surprise for my young parents that I was born a girl, but the bigger surprise was that I was born without my left arm below the elbow. Fortunately, at that time, the standard practice was to refer children with congenital birth anomalies to the orthopedic unit of the Shriners Hospital. There was never a question of whether or not to fit me with a prosthesis. The question was, “When?”

I know that many parents struggle with making that decision for their children today, particularly with all of the conflicting information they hear; that is, children with upper-limb deficiencies do just fine and do not need a prosthesis, or children generally reject upper-limb prostheses. I think both statements are true for some, especially the first. However, long-term issues with sound-side overuse syndrome and body symmetry can become problematic later in life. The second statement can be true if a parent waits until the child is older to be fit. Fitting a child after he/she has learned to do everything without a prosthesis can actually decrease the child's function because adjusting to a prosthesis is such a difficult undertaking. I can only imagine how difficult it must be to make decisions about the type of prosthesis one should choose when it comes to dealing with an acquired amputation.

In my case, the decision was pretty much made for my parents and me, and because of that, I started doing bimanual tasks at midline and with the appropriate body posture at a very young age. I was fit with my first prosthesis at 9 months old. It looked like a typical figure-of-eight harness and hook setup, but the terminal device (TD) was made of a soft rubbery material, and it was not activated by the cable. By age two, my prosthesis was cable activated and I learned how to open and close the device on my own. I do not remember a time in my life when I did not wear a prosthesis. It has always been a part of me, although over the years I have worn different devices during different seasons of my life. I hope that by sharing my experience with different devices and highlighting the benefits and limitations of the devices I have worn over the years, others who are faced with these choices can feel more informed.

One option, of course, is to go without a prosthesis. Having been born with a below-elbow limb deficiency, I have always found that I can do anything with or without a prosthesis. Because I am such a consistent wearer, however, I find that accomplishing my everyday tasks is much easier with a prosthesis than without. People with acquired amputations learn to do many of their daily activities using only one hand while their affected limb is healing. Sometimes, people find it easier to adapt to living with one hand over adapting to a prosthesis. Not wearing a prosthesis is a perfectly viable option for moving through life, especially if a person feels successful with his/her accommodations and adaptations. In addition, the length of the residual limb can factor into whether one is to be fit with a prosthesis. Individuals with longer limbs may opt to use only their residual limb and sound side or they may choose a prosthesis because the fitting and control mechanisms are somewhat easier. The higher up the arm the amputation is, the more difficult the fit and limited the function of a prosthesis. On the flip side of that, however, is the higher the amputation, the more useful a prosthesis can become.

For the past 28 years, I have worn a myoelectric prosthesis. In my experience, the suspension methods, battery life, and TD options have only gotten better over the years. I currently wear a carbon-fiber forearm with a custom silicone socket and an electric terminal device (a myoelectric hook). I have customized the look of my forearm by covering it with Swarovski crystals, and my prosthesis is not only extremely functional, but also it is a reflection of my creativity and spirit. I love to teach, and my prosthesis gets a lot of attention, which allows me the opportunity to teach others about limb differences. There was a time in my life when I was a teenager, however, when I did not want the attention that my prosthesis brought. I transitioned from a cable-operated hook to a myoelectric hand right before I went off to college. I absolutely loved the anonymity that the hand afforded me. I could walk around campus and no one knew that I was missing my arm. As a young woman at that time in my life, having a hand that was extremely functional and blending in was very important to me.

Today, there are so many options to consider when selecting a myoelectric TD. Ideally, a person could have two TDs or two prostheses. Unfortunately, most people are allowed to select just one device. So how does one choose? One of the best ways to become familiar with the benefits and limitations of the different devices is to speak to individuals who wear them. Peer mentoring programs like AMPOWER and the Amputee Coalition's program can help persons with new amputations to connect with others who are successfully moving through life wearing these devices. The manufacturers' Websites can list the features and benefits; however, there is nothing like seeing the device in action. There are hands with multiarticulating digits and compliant grasps, there are simpler versions of hands, and there are hooks. Each of these devices has features that can benefit the user. When deciding which device is right, it is important to look at your vocation, avocations, and goals and choose the device that best meets your needs. Often, people will go online and find the most technologically advanced, most expensive device and assume that it is the best on the market. That is not the case in most situations. Being an educated consumer means carefully evaluating the options before making a decision. Some devices are better for light duty versus heavy duty, some can get wet while others cannot, some offer compliant grasps while others offer fixed grasps. Having conversations with an experienced upper-limb clinician and also meeting others in similar situations will help narrow the choices.

Another option is to wear a cable-operated device. Unlike the myoelectric device that relies on a battery to power the TD, the wearer uses gross body movements to open and close the TD. This type of system is very durable and simple to use. There are voluntary opening and voluntary closing devices whereby the force exerted on the strap either closes or opens the TD. I wore a cable-operated prosthesis from the time I was 9 months old until I was 17. It was always reliable, comfortable, functional, and easy to operate. Once I switched to myoelectrics, I did not ever go back to a cable-operated device because I needed to alleviate the pressure under my sound side arm from the strap. That control strap is one of the drawbacks to wearing a cable-operated device in that it can eventually cause nerve impingement. If a person can tolerate the strap, however, the cable-operated system is a great option for longevity and durability. Functionally, cable-operated systems are very consistent. However, aesthetically, they may not meet the needs of everyone.

One nice feature of cable-operated devices is that they can become adaptive devices very easily and quickly. A functional everyday prosthesis can become many prostheses in one with a quick-disconnect unit that allows for a multitude of TDs. Different adaptive devices can be placed at the end of the prosthesis to allow for weight lifting, holding a golf club or tennis racket, or even a bow and arrow. The possibilities are almost limitless. If a person enjoys a number of avocations, this style of prosthesis might be the best option, especially if he/she is limited to only one prosthesis.

Finally, the functional aesthetic prosthesis is a great option for individuals who really want the look of the hand but cannot tolerate the weight of a myoelectric prosthesis. Although this style does not offer grasping capabilities, it does offer opposition to the sound side and is functional in that regard. I have worn a functional aesthetic prosthesis in the past and enjoyed the cosmesis and lightweight design. There is no threat of ruining it when it gets wet, so it was a great option at the beach or pool. Fortunately, I think today, there is less of a negative stigma associated with limb differences, so when people are making prosthetic choices, they can feel empowered to make a choice that meets their functional and aesthetic desires. Customizing a prosthesis to reflect a person's personality and style has become common practice as people embrace their challenges as survivors versus victims of their circumstances.

People have often asked me, “If you could go back and live your life with two hands, would you?” My answer has always been the same, “Not a chance.” Although I have experienced many struggles with this difference, I have experienced exponentially more wonderful moments in my life as a result of being born this way. When I was about 15 years old, I saw a refrigerator magnet that said, “Life isn't about finding yourself, it's about creating yourself.” That phrase stuck with me. We have so much power within us to create the lives we desire. By choosing love, hope, humility, and service, we have the power to change our world and the world around us. It is my goal every day to help improve the experience of people coping with the challenges of navigating life after limb loss and ensuring that their highest priority needs are met through compassionate, thoughtful care. It is my honor to get to serve this very unique community in this way, as it reminds me that no one ever has to feel alone.

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USER’S PERSPECTIVE: BODY-POWERED PROSTHESIS

MIKE ST. ONGE

I was 34 years old at the time I contracted pneumococcal pneumonia in January of 2000. This led to systemic gangrene resulting in amputation of all four limbs. My amputations are a very short below the elbow on my left arm, through elbow on my right arm and bilateral transtibial amputations on my lower limbs. I spent 5 months in four different hospitals, with the first 2 months spent in a drug-induced coma. My amputations and most of the skin grafts were performed while I was in a coma. I spent another 7 months in outpatient rehabilitation.

I received my prosthetic arms near the Fourth of July and my prosthetic legs the last week of August, roughly 6 months after my infections and amputations. I spent all of 2000 recuperating my strength and stamina and most of 2001 was spent on expanding my level of independence with my prostheses. This included learning when prosthetic arms could outperform just using my residual limbs, determining which feet might be most suitable for comfortable walking, and learning how to drive again. This learning was interrupted on multiple occasions (2001, 2002, 2004, 2006, 2008) with major surgeries to correct cosmetic damage to my face and improve my lower limbs for weight bearing.

When asked why I wear a BP hook, the simplest, most direct answer is that it was what I was given in the beginning. Although that answer is succinct, it is somewhat misleading. I have been a person with amputation for 17 years and I have been fortunate enough to experience many different types of upper- and lower-limb prostheses. I have been able to travel widely over the years attending many different conferences, seminars, workshops, camps, and events oriented toward both professionals and laymen. I have experimented with different BP TDs and suspension methods and have had the opportunity to utilize a myoelectric Greifer (a robust electric hook) for an extended period.

During the time I have been this way, people have approached me to talk about my amputations and often refer to “that hand on TV” followed up by comments like “isn't it amazing what they can do now.” Many people are a bit surprised that I would still choose to wear a BP hook when there are some really incredible, realistic myoelectric (myo) “hands” out there. I am always open to the opportunity to advocate for people with limb loss and educate people as to why I wear what I wear.

My initial foray into someone's preconceived notion is to explain the fundamental differences between a BP and a myo on how each one operates. Only then can I explain the differences in weight; strength; speed; input control; dependability; field serviceability; sensory feedback; visibility around or through the device; cosmesis; the impact of environmental factors like dirt or water, heat, or flame; and the associated costs and coverage by insurance companies. I have found that many of these considerations are better understood when I use an analogy by contrasting a smart phone to a pencil.

Smartphones are great, but we still use pencils… Why? Smartphones are great devices, but when they break, or more commonly, when the battery dies, we get very frustrated at our inability to communicate via call, text, or email. However, a smartphone is just one tool we use for transmitting information. When we need to “work,” many prefer to use pencils and paper.

Similarly, modern myo hands are great devices, but they are prone to breaking and, like cell phones, rely on regular recharging of their battery. For some who have become reliant upon this type of device, when it is not functional, it can lead to anger and frustration. I have found that I prefer BP hooks to myo hands for dependability, durability, and reliability. A BP hook can be repaired anywhere by almost anybody (I repair my own), while myo hands need to be sent back to the manufacturer and may be gone for weeks at a time. Although loaner TDs are often available from manufacturers during this repair period, if the damage is to the prosthesis itself, the user may be left without a functional device as “backup” prostheses are usually not covered by insurance companies and can be cost prohibitive to procure on your own.

Most people have experienced some kind of mishap with their smart phone, so it is easy for them to understand that once we become reliant on technology─and that technology fails─our life can get turned upside down. Can you remember your friends' phone numbers anymore or drive somewhere with a paper map with confidence?

The ultimate question that needs to be understood is, “as the wearer, what do I want from my device.” As an informed consumer, I had to educate myself on the pros and cons of different upper-limb prostheses. In the beginning, the amount of information out there can be overwhelming. This must be coupled with considerations like what is covered by your insurance and any associated copays.

When asked such questions, the person with a new amputation just wants “their hand back” and inquires, “What can you give me that is going to work like that?” Unfortunately, the human hand is very complicated, and all prosthetic substitutes fall short of its strength and dexterity, which returns the consumer to the more practical question, “What do you want from that device?” Because of my many years as a person with amputation and staying abreast of current technology, I am aware of what is out there. However, more importantly, I understand myself and what I am looking for from my prostheses. For me, I require a prosthesis that is durable and dependable that I can repair when needed.

Another factor in my prosthetic selection is that I am more interested in function over form. Also, being married and mentally secure in my identity at the time of my acquired amputations, I have never worried about what I look like wearing a hook. However, for others, appearance and form are more valued in their decision making.

My selection process for an upper- or lower-limb prosthesis includes the following:

Acceptance—Accept that a limb is gone, only then will any replacement be tolerated.

Education—Learn about the different prosthetic options available for a missing limb or joint.

Pros/Cons—Weigh the benefits and detractions of each device: functional, passive, or myoelectric.

Know thyself—What are my basic needs? What are my additional wants?

Peer discussion—Talk to others with similar problems or devices.

Evaluate—Can I try before I buy?

Satisfaction—Did that device live up to my ideas and expectations?

Coverage—How will this device be paid for?

I have found that going through these considerations has helped me make decisions about my prostheses to ensure I have the devices that are most consistent with my needs, preferences and resources.

Another point in my prosthetic selection is my upper-limb amputation levels. My right arm has been amputated through my elbow joint as a disarticulation and my left arm has been transected just below my elbow. Before my illness and amputations, I was right handed. Now I am left handed because my left side has one more natural joint, my elbow, which makes the use of that prosthesis slightly more natural or intuitive.

Originally, I wore prostheses on both limbs, but I quickly discovered that I was using only my left arm for most tasks. This may have originally resulted from delays in fitting the right limb with a prosthesis (approximately 2 to 3 months after the left), learning to function with my environment without any prostheses, and the activities I was frequently trying to do early in rehabilitation, specifically picking up my infant daughter and steering an electric wheelchair.

Because my right arm is an elbow disarticulation, it is fitted much like an above-elbow prosthesis, only with outside locking hinges. Although this design is functional, it is not greatly intuitive in its use. The operation is not that fluid. The forearm is “stationary” in that it must be locked into a position before opening or closing the TD (hook). This “step-by-step” function (described by prosthetists as “sequential” control) inherently leads to a nonfluid process.

I quickly discovered the limitations of my right prosthesis and would frequently remove it to do bimanual tasks like picking up my daughter. Because my entire right upper arm was encased in the socket, I did not have tactile sensation and had difficulty determining how much, or how little, pressure I was applying while picking her up. This led to sometimes squeezing her too hard and hurting her or not hard enough and she would slip from my grasp. I overcame this dilemma by removing my prostheses and using my residual limbs.

I also had plenty of similar “slips” or mishaps while trying to steer my electric wheelchair. The combination of a plastic joystick and a smooth round forearm led to quite a few dings in door jambs and scrapes in the walls. Again I learned that it was safer and easier to drive while not wearing my right prosthesis. It took about 3 months of doing activities of daily living with and without my right prosthesis before I learned that it was less physically and maybe, more importantly, less mentally tasking to do things while not wearing it, so I asked that it be removed.

My current level of independence and functionality has not been impeded by a lack of a right hand or prosthetic device. This anecdotally fits what I have observed with many persons with unilateral upper-limb amputation who choose not to wear a prosthesis. Even though I was right-hand dominant before my amputations, the actual daily use of a prosthesis on that side was not effective, efficient, or fluid, ultimately leading me to reject it.

As with most anything in our life, we try to make choices that hopefully make us happy and comfortable. I have been asked if I could, would I want my limbs back? I have thought long and hard about this answer and it is a solid “no.” Had I been asked 6 months before this happening if I could live this way, I would have also said “no.” But, 6 seconds after waking up from that coma I said, “I got this.” I have been very blessed during all of this and have been afforded so many opportunities that would never have come my way if I had not fallen ill and lost my limbs. Yes, of course, there are many difficult times and frustrations, but I had tough times in my life before my amputations. Those challenging items are still there, just different.

I am not only happy and content with my current situation in life, but I also challenge myself to do more and learn different things. After my amputations, I have been fortunate enough to go skydiving, snow skiing, jet skiing, surfing, and horseback riding. I have snorkeled in Hawaii, climbed Mayan pyramids, ziplined through a tropical rain forest, and traveled the country mentoring to others with limb loss. I have also been involved with research projects and lectured to professionals. None of these opportunities would have come my way if I still had my limbs.

The prostheses I have chosen afford me the durability, comfort, and capability to live my life to the fullest of my ability. I keep a careful watch on current and future technology and am grateful for the advancements being made in the field. My choice of a single BP upper-limb prosthesis allows me to pursue most of my everyday activities and most of my ambitions with ease and confidence.

Keywords:

upper-limb prosthesis; prosthesis; individual with amputation; limb deficiency

© 2017 by the American Academy of Orthotists and Prosthetists.