It is no secret that limb loss has numerous adverse effects on a person's physical, emotional, psychological, and social health. Numerous challenges need to be addressed to improve amputees' quality of life. A study published in December 2021 in the National Center for Biotechnology Information (NCBI) looked into improving the quality of life of above-knee amputees by collecting user data to enhance prosthetic knees.
Advances in prosthetic technology have undoubtedly significantly increased the availability of powered prosthetic ankles and microprocessor-controlled knees. However, the user adoption of powered prosthetic knees has remained low due to its cost, usability, weight, and lack of functional benefit for most above-knee amputees.
The researchers deemed the study necessary because above-knee amputees typically report lower satisfaction with their prosthetic limbs than below-knee amputees. This is because the former exhibits markedly reduced energy efficiency, gait speed, and compromised symmetry while also experiencing greater postural instability and a high risk of falls.
The answer to these issues lies in the widespread use of microprocessor-controlled knees. However, the researchers noted that conventional ones have difficulty recognizing and adapting to varying inclines, gait speeds, stairs, and other uneven terrains, usually encountered within a prosthetic user's daily environment.
The study was based on an extensive survey of unilateral above-knee amputees to characterize their subjective experience with their prosthetic limbs as well as their preferences about the features and functions of an ideal prosthesis.
The study subjects ranged from 18 to 79 years old. They were recruited from participating rehabilitation centers and online through affiliated patient support networks on social media.
Furthermore, there were more traumatic amputation cases—about 78.9%—in the study sample. This number markedly differed from the estimated 16.4% of above-knee amputees among the total number of lower-limb amputations.
The data gathered during the survey provided:
A characterization of above-knee prosthetic users.
Their experience with their current prosthetic limb.
Their preferences for an ideal prosthesis.
User experience and satisfaction
Overall, study subjects using microprocessor-controlled prosthetic knees use their prosthetic limbs more frequently than those using non-powered knees. The first group also reported a significantly greater sense of independence and was more satisfied with their prosthetic devices.
Microprocessor-controlled prosthetic knees have been shown to reduce falls in amputees with lower mobility grades as well as improve motor functions. In addition, microprocessor-controlled prosthetic knees promote greater overall movement control, dynamic stability, and functional mobility.
The study findings also reinforce a picture in which technologically advanced above-knee prosthetic limbs can be powerful tools in promoting user mobility and self-sufficiency. However, this must be employed as part of a comprehensive rehabilitation program that emphasizes functional training and proactive psychological support.
Based on past and present evidence, the researchers conclude that more advanced above-knee prosthetic limbs can be more effective than traditional ones at realizing user potential.
The ideal above-knee prosthesis
Users of traditional prosthetic knees identified the importance of stability first. In comparison, users of microprocessor-controlled prosthetic knees expressed a strong preference for stability as well as lifestyle adaptability.
The subjects identified more specific tasks like gait on uneven terrain, stair ascent, and ramp walking as second in importance.
According to researchers, the only pronounced difference between groups is the elevated preference for active cooling by microprocessor-controlled prosthesis users. This suggests more increased overall activity levels that would naturally result in more frequent sweating and volume changes in the residual limb.
The researchers noted that the findings are consistent with the hypothesis that more advanced above-knee prosthetic limbs positively influence the users' overall sense of personal independence, prosthesis acceptance and ownership, and, ultimately, their overall health and well-being.
Moreover, the study found significant differences in daily living autonomy between users of microprocessor-controlled knees and traditional prosthetic knees: the sense of independence is higher among non-traumatic amputees.
This suggests that above-knee prosthetic users with lower overall health status may get more significant marginal benefit from the use of advanced prostheses and that the current standard-of-care guideline of prescribing microprocessor-controlled prosthetic knees to more capable users should be more carefully evaluated.
Do you use a microprocessor-powered or traditional prosthetic knee unit? What do you think of the findings?