Predictive Outcome Measures Versus Functional Outcome Measures in the Lower Limb Amputee

INTRODUCTION John Ware 1 wrote, “Life has two dimensions: quantity and quality. ” The distinction between the two entities is well illustrated in the common greeting “may you have a long and healthy life” (p. 473). Length of life is expressed in terms of average life expectancy, mortality rates, death due to specific causes, and numerous other indicators. When defining the second dimension, quality of life encompasses standard of living, the quality of housing and the neighborhood in which one lives, job satisfaction, and many other factors. With regard to the amputee, it has been well established that for a number of vascular amputees who have undergone an amputation due to the magnitude of vascular compromise, life expectancy is relatively short. For the amputee who has lost a limb to tumor, trauma, or congenital condition, amputation has little or no bearing on life expectancy. Medical interventions have improved care to the point where the impact of amputation on longevity has decreased tremendously. So, as quantity of life improves, what about quality of life? The World Health Organization (WHO) defined health as a “state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity. ” Health connotes “completeness” – nothing is missing from the person; it connotes “proper functions” – all is working efficiently. That would suggest that if a prosthesis has the ability to improve the quality of life for the amputee, then it should be provided. This is not to say that the “best” prosthesis belongs on all patients, primarily because what is considered the “best” for one person may be a hindrance to another. For example, a prosthetic foot that provides a mechanical high energy return at terminal stance, propelling the limb into the swing phase of gait will be a tremendous asset for a strong person with a fast cadence. Conversely, the same foot might only throw a frail, elderly person off balance, resulting in the fear of falling and a tentative gait pattern. Unfortunately, we are not sure what the best prosthesis is for the different amputee populations. The dilemma becomes apparent when trying to determine what are the best prosthetic components for each individual amputee. Common indictors such as materials, time of fabrication, complexity of design, and cost do not dictate the “best” components for each individual. Matching functional ability with the proper components is the solution for optimizing physical performance. This is not a novel concept. In fact, if questioned, most clinicians would agree that marriage of the correct prosthetic components for the appropriate level of function is one of the primary goals of the rehabilitation team. However, this goal is apparently not so easy to achieve. At the very root of the problem is the inability to define a “successful prosthetic ambulator. ” There are many interpretations for this common goal, from simply using the prosthesis “about an hour per day” to “prosthetic use without external support on a daily basis. ” There is no agreement anywhere with regard to the threshold of “successful prosthetic use. ” The question is whether there is one threshold or many as severe authors have advocated by virtue of offering multilevel functional scales and indices. There is a wide variety of indices published within the literature. In the United States today, it appears that only one index is of significant consequence to Medicare and managed care providers, the Durable Medial Equipment Regional Carrier (DMERC) K codes or Medicare’s Functional Classification Level (MFCL) index. Its exceptional importance is solely because assignment to a particular level of function within this index determines the level of prosthetic care, and, consequently, the financial reimbursement a prosthetist will receive for the prosthetic services rendered. After an extensive review of all available indices, the descriptors and selection of number of levels chosen for the MFCL index appears to be well constructed. This assumption is predicated on the basis that the MFCL index has a range from a fully dependent bed-bound amputee to a recreational athlete capable of higher level activities. Definitions clearly describe observable differences between each of the five levels using seemingly commonly assessed functional skills. It must be kept in mind, however, that as attractive as the MFCL may appear to be after initial examination, it was created based on content validity of a Medicare subcommittee and was not based on any formal scientific research. The use of a functional index seems to be reasonable, but ROBERT S. GAILEY, PhD, PT, is affiliated with the University of Miami School of Medicine, Department of Physical Therapy, Miami Veterans Affairs Medical Center, Miami, Florida.