Lower-Limb Prosthetic Prescription: The Importance of Outcomes and Data
Article originally published in Edge Advantage.
There are an estimated 65 million people that live with limb amputations globally, with 1.5 million people undergoing amputations—mostly of the lower limb—each year. Most people with amputations need access to prosthetic services, and this need is expected to double by 2050. [1] With a limited number of physicians with sufficient expertise in prosthetic prescription and amputee rehabilitation, there is a growing need for well-coordinated teams to guide optimal prescription and rehabilitation. [2]
A key component of the rehabilitation process for people with lower-limb amputations is the provision of prosthetic care. Generally, the goal for patients with limb loss is to restore function and quality of life as much as possible without overlooking aesthetics. Lower-limb prostheses can give patients a chance to enhance their ambulation by decreasing the excess energy requirements of crutch walking. Additionally, prostheses can improve the patients’ balance with the restoration of bilateral proprioceptive feedback through the residual limb-prosthesis interface. Improved mobility also gives users the chance to gain independence by doing most of their activities of daily living without the assistance of another person.[3]
Prosthesis users should be suited with the best technology to not only meet their physical needs and restore functionality as much as possible but also to ensure they are satisfied psychologically and socially. Gone are the days in which rehabilitation would only concern functional recovery—the paradigm of care quality has now shifted to include psychosocial well-being. However, reported rates of prosthesis use can vary from 49 to 95 per cent, indicating that, as an intervention, prosthesis prescription may not always be effective or the most appropriate, which can lead to the technology not always being used to its full potential.[4] It becomes important to understand how prosthetic prescription can be improved to best serve the needs of the user, further develop the patient-healthcare team relationship, and rectify the use of resources, avoiding the underutilization of available technology.
A lower-limb prosthesis can be divided into several components: the prosthetic socket, the prosthetic suspension, the prosthetic ankle-foot mechanism, and for higher levels of amputation, the prosthetic knee. Physicians’ prosthetic prescriptions should include a diagnosis, medical and functional justification, and the device type with components sufficiently detailed. Despite the level of technicality that is necessary to provide all these details, prescriptions for lower-limb prostheses are primarily based on empirical knowledge, and the existence of a myriad of options for each component turns it into a convoluted problem. Prescription criteria are based mainly on physicians’, therapists’, and prosthetists’ subjective experiences, and the decisions seem to be deeply influenced by peer recommendation and local practices. This behaviour can lead to reluctance the adoption of new technologies, and the dissemination of certain components and certain brands instead of others. On the other hand, third-party payers frequently require justification for purchasing costly prostheses and components. From the perspective of prosthetic provision, not only the dissemination of information about different technologies and components is of utter relevance, but also a deeper understanding of what leads to prosthetic use compliance.
The prescription process should involve a multidisciplinary team: the patient, the prosthetist, the prescribing physician, and the rehabilitation therapist, for example. This team approach is crucial to enhance communication, timeliness, and appropriateness of a prosthetic limb fitting, eventual functional usage, and improvement of patient satisfaction, giving attention to the patient’s specific needs.
Nowadays, there is no consensus on the most important outcomes to measure in lower-limb prosthetic rehabilitation or on the specific outcome measures to be consistently used in prosthetic rehabilitation. For example, Deathe et al. have described how centers of care in Canada evaluated patient outcomes: 31 per cent reported that they did not use any formal outcome measure to assess patient outcomes. [5] Out of those centers that did use formal measures, 67 per cent did not use self-reported measures, thus missing the users’ perspectives on their rehabilitative outcomes.
In general terms, a prosthetic prescription should be based on matching the patients’ functional needs with the functional capacities of the prosthetic devices. But their general health, mental state, residual-limb health, pain, living circumstances, and vocational/recreational interests and motivations must be considered in addition to the level of amputation.
Before moving forward with prosthetic fitting, the individual’s tissue healing and relative pain control should be verified, but it is also important to monitor some conditions that can complicate or preclude prosthetic fitting, such as joint contractures, volume changes, phantom pain or complex regional pain syndrome, tissue adhesions, and overlying skin conditions. Monitoring these conditions is crucial because the limb will be in contact with the prosthetic socket (or with an interface), and the general health of the limb can influence a better or worse socket fit that potentiates or hinders comfort and stability.
The changes in patients’ residual limbs are not the only aspects that require attention. Likewise, prostheses require maintenance, repair, and periodic replacement, and everything that was mentioned needs to be considered when prescribing a new prosthesis or specific component for replacement.[6] It is problematic when prosthetists know their patients need new prosthetic components to improve their quality of life, and the payers refuse to cover these costs.
Prosthetic prescriptions are often driven by the expected functional outcomes and activity levels of each patient. In 1995, Medicare established K-levels as a means to quantify the need and potential benefit of prosthetic devices for patients after lower-limb amputations.[7] According to the American Academy of Orthotists and Prosthetists, there is no a method that is considered the gold standard for establishing K-levels. There are several tests that can be administered to determine the patients’ activity levels, such as the Patient Assessment Validation Evaluation Test (PAVET), Prosthesis Evaluation Questionnaire (PEQ), Timed Up and Go (TUG), timed walk tests, distance walk tests, and Amputee Mobility Predictor (AMP). By using this system, the physician and prosthetist determine the patient’s ability to reach a defined functional state within a reasonable period of time. The K-levels are divided in five tiers: K-0, in which the patient does not have the ability or potential to ambulate or transfer safely with or without assistance and a prosthesis does not enhance their quality of life or mobility; K-1, where the patient has the ability or potential to use a prosthesis for transfers or ambulation on level surfaces at fixed cadence, typical of the limited and unlimited household ambulator; K-2, (typical of a community ambulator) in which the patient has the ability or potential for ambulation with the ability to transverse low level environmental barriers such as curbs, stairs, or uneven surfaces; K-3, in which the patient has the ability or potential for ambulation with variable cadence, typical of the community ambulator who has the ability to transverse most environmental barriers and may have vocational, therapeutic, or exercise activity that demands prosthetic utilization beyond simple locomotion; and K-4, where the patient has the ability or potential for prosthetic ambulation that exceeds the basic ambulation skills, exhibiting high impact, stress, or energy levels typical of the prosthetic demands of the child, active adult, or athlete.[8]
The cost of prosthetic components has risen, and the insurance companies have started asking additional questions and requiring more data to justify prosthetic prescription or the replacement of prosthetic components. It is important to monitor patient evolution on each follow-up visit and to ponder if patients need new components or adjustments to their prostheses. If so, the multidisciplinary team must be called into action, defining a strategy and implementing it in the shortest time possible.
Any determination should use the results from studies on biomechanical aspects, and functional characteristics of several prosthetic components as prescription criteria is not straightforward. Outcome measures differ from study to study, therefore comparison or meta-analysis of the results is challenging.[9] The development of certain clinical guidelines for a prosthetic prescription (in terms, for example, of what studies should be done with each component and what metrics and outcomes should be evaluated) is a way of making healthcare more consistent and efficient and diminishing the gap between what clinicians do and what scientific evidence supports. Moreover, in the long run, data-driven guidelines are a useful tool to ensure cost-effectiveness. Creating these guidelines would make it easier to compare different treatments and interventions, enhance accountability in prosthetic services, and understand why and when prosthetic technology should be provided. Successful outcomes occur when there is a match between prosthetic component function and patient abilities, goals, and daily use.
References
Schaffalitzky, E., P. Gallagher, M. Malcolm, and T. Stephen. 2012. Developing consensus on important factors associated with lower-limb prosthetic prescription. Disability and Rehabilitation 34(24):2085-94.
Donaghy, C., S. J. Morgan, G. E. Kaufman, and D. C. Morgenroth. 2020. Team approach to prosthetic prescription decision-making. Current Physical Medicine and Rehabilitation Reports 8:386-95.
Bowker, H. and J. Michael. 2002. Atlas of Limb Prosthetics [Online]. http://www.oandplibrary.org/alp/.
Schaffalitzky, E. 2010. Optimising the prescription and use of lower limb prosthetic technology: A mixed methods approach.
Deathe, B., W. Miller, and M. Speechley. 2002. The status of outcome measurement in amputee rehabilitation in Canada. Archives of Physical Medicine and Rehabilitation 83:912-18.
Gailey, R. S., K. E. Roach, and E. Brooks Applegate, et al. 2002. The Amputee Mobility Predictor: An instrument to assess determinants of the lower-limb amputee’s ability to ambulate. Archives of Physical Medicine and Rehabilitation 83(5):613-27.
Van der Linde, H., J. Geertzen, and C. Hofstad, et al. 2003. Prosthetic prescription in the Netherlands. Prosthetics and Orthotics Internationational 27:170-8.
Liao, C., F. Seghers, and M. Savage, et al. 2020. Product Narrative: Prostheses, ATScale.
Centers for Medicare & Medicaid Services, 2017. Lower Limb Prosthetic Workgroup - Consensus Document.
