On September 16–17, 2016, the American Academy of Orthotists and Prosthetists convened its 12th State of the Science Conference, with the event largely focused on the various control options and design types for upper-limb prostheses. Using a systematic review commissioned by the Academy and published by Carey et al.1 in 2015, a multinational, multidisciplinary panel was assembled to discuss a range of considerations and perspectives surrounding this topic. These perspectives included those of the clinical prosthetist in the private care setting, rehabilitation clinicians from US Department of Veterans Affairs (VA) and military health care settings, the physiatrist, the occupational therapist, the end user, global observations and trends, engineering, developing technologies, and associated medical procedures and outcome assessment.
A number of observations were brought forward that will receive additional treatment in these proceedings. Chief among them was the trend in the US health care system to approach control options for upper-limb prostheses in a hierarchal fashion. The premise of this approach may be based on the convenience of introducing control options in an order of increasing complexity, beginning with the choice of no prosthesis and proceeding with passive and body-powered designs and culminating in more technologically advanced externally powered options, frequently epitomized by myoelectric and hybrid control. This paradigm has led to a number of inaccurate dispositions. In a private health care system that remains characterized by both “high-end” and “low-end” coverage, any perceived ranking of prosthetic options could be used to exclude access to prosthetic care that is construed as “higher” or “advanced,” in deference to more basic care.
Within this unfortunate mindset, coverage of a myoelectric prosthesis may be denied outright as a policy exclusion or contingent upon the inability of a “standard body-powered device” to meet a patient's functional needs.2–4 Both positions are based upon the mindset that body-powered prostheses should be considered the standard of upper-limb care, and myoelectric control exceeds that standard. Importantly, to the extent that any “standard” in upper-limb control strategies has been identified globally, it varies within financial resources and prevailing views of different health care systems. In the United States, the viewpoint of body-powered control as a standard of care is observed in the private sector.2–4 Within the Veterans Health Administration health care system, where decisions are less influenced by cost-containment policies and strategies, body-powered and myoelectric systems are used with equal prevalence. Within Western Europe, myoelectric devices are overwhelmingly viewed as the standard of upper-limb prosthetic care.
Clearly, patients should be managed with the technology and prosthetic design that is most appropriate to their presentation, functional needs, and personal goals. This is best accomplished when the range of available prosthetic options are not viewed as hierarchical (Figure 1).
Within the framework of a nontiered view of upper-limb prosthetic choices, it must be understood that the most appropriate prosthesis or combination of prostheses varies with each individual, his/her physical presentation, his/her vocational and avocational activities and environments, and a host of other considerations. More directly, the most advanced, or expensive, prosthetic options may not be the “best” prosthesis for a given individual. Understanding the benefits and limitations of various prosthetic options must be conveyed in accessible language and may be facilitated in part through peer mentorship and its associated resources.
Conspicuous within any study of the current published evidence on upper-limb prosthetic rehabilitation is that lack of empirical evidence to support clear practice guidelines. For example, of the 27 recommendations in the VA/DoD Clinical Practice Guideline for the Management of Upper Extremity Amputation Rehabilitation, only 1 is empirically based, with the remaining 26 statements supported by expert opinion.5 This is a product of both the general paucity of research in this area and the low volumes and heterogeneous sampling that characterize existing upper-limb prosthetic research. However, such limitations are to be expected, given the comparatively low volume of upper-limb loss and deficiency. Of the over 2 million estimated individuals living in the United States with limb loss, just more than 500,000 involve the upper limb, and of these, only an estimated 41,000 are “major upper-limb amputations” (i.e., excluding finger amputations).6 By contrast, diabetes affects over 25 million people in the United States, or slightly more than 8% of the population.7 Similarly, the prevalence of hypertension in the United States is more than 3 times greater, reported at just fewer than 30% of the population.8
Realistically, the limitations associated with the empirical study of a demographic with a national population base of just over 40,000 individuals will continue to challenge future research efforts. Within these limitations, the collective observations of those rehabilitation professionals, including physicians, therapists, and prosthetists, who have amassed considerable experience in working with this patient population must be recognized as the most informed source of available evidence. Future empirical research efforts will likely require broad, potentially global collaboration to augment study sample sizes across the prosthetic design options of body power, external power, and passive systems as well as the decision not to use a prosthesis.
An emerging and increasingly relevant consideration in upper-limb prosthetic rehabilitation is the role of surgical interventions in defining the candidacy and functional potential of individuals with upper-limb deficiency. Although the quality of the upper-limb amputation has always had some bearing on prosthetic design and acceptance, this influence has been greatly magnified with the introduction of targeted muscle reinnervation, a surgical procedure that fundamentally alters an individual’s potential for prosthetic function. Osseointegration, along with imbedded sensory and motor electrodes, represents additional arenas where surgical intervention will be required to allow individuals to attain the greatest functional outcomes. However, in such instances, consideration must be given to available funding resources for the prosthesis itself. All of the surgical arenas described above require the use of more expensive, technologically advanced, externally powered prostheses. In the absence of access to the associated prosthetic care, the benefits associated with these surgical interventions will never be realized.
Of related concern, as the surgically assisted possibilities associated with externally powered prostheses continue to expand, the collective costs are likely to drastically increase. Fiscally determined limitations to the access of such advanced rehabilitation solutions are likely to result in appreciable limitations in function, quality of life, and cumulative rehabilitation, expanding the divide between the various financially determined standards of care that unfortunately already exist in patient care.
As the collaborative possibilities associated with developing prosthetic technologies and the creative surgical advances cited above become more defined and available, the rehabilitation community will need to quantify the associated benefits to function and quality of life. To do so will require the use of meaningful outcome measures. As efforts are undertaken to define a core set of meaningful outcome indices for this population, measures should have a high enough ceiling to ensure that they will remain meaningful as prosthetic and surgical advances expand functional abilities.
Core considerations in the outcomes attained during upper-limb prosthetic rehabilitation will need to examine fine motor activity and dexterity, the performance of activities of daily living, perceived disability, quality of life, satisfaction, and device utilization. In addition, as this is a population that experiences pain from a host of sources, including limb pain, phantom pain, and overuse syndromes, the prevalence, impact, and mitigation of the pain experience requires greater understanding. With regard to the choice of prosthetic type, the complex relationships between the type of prosthesis, its underlying control strategies, overall utilization, and associated pain experiences must be better understood.
1. Carey SL, Lura DJ, Highsmith MJ, et al. Differences in myoelectric
and body-powered upper-limb prostheses: systematic literature review. J Rehabil Res Dev
6. Ziegler-Graham K, MacKenzie EJ, Ephraim PL, et al. Estimating the prevalence of limb loss in the United States: 2005 to 2050. Arch Phys Med Rehabil
7. Centers for Disease Control and Prevention. National Diabetes Fact Sheet: National Estimates and General Information on Diabetes and Prediabetes in the United States, 2011
. Atlanta, GA: US Department of Health and Human Services, Centers for Disease Control and Prevention; 2011. Available at: http://www.familydocs.org/f/CDC%20Diabetes%20fact%20sheet-2011.pdf
. Accessed March 30, 2017.
8. Nwankwo T, Yoon SS, Burt V, et al. Hypertension among adults in the United States: National Health and Nutrition Examination Survey, 2011–2012. NCHS Data Brief