Myoelectric and Microprocessor-Enabled Prostheses

Key Messages

What Is the Issue?

• Advanced prostheses offer people living with upper-limb or lower-limb amputations the potential for more complex movement compared to conventional or body-powered devices. However, advanced prostheses are expensive, require more training, and can require more maintenance than body-powered devices.
• A review of the literature can inform health care decision-making regarding these devices by summarizing their clinical benefits and cost-effectiveness compared to body-powered devices.

What Did We Do?

• To inform decisions regarding advanced prostheses for amputations, we conducted a Rapid Review to summarize evidence that compared the clinical effectiveness and cost-effectiveness of myoelectric and microprocessor-enabled prostheses to conventional or body-powered prostheses. We also sought to identify evidence-based guidelines regarding the use of myoelectric prostheses and microprocessor-enabled prostheses for this patient population.
• We searched key resources, including journal citation databases, and conducted a focused internet search for relevant evidence published since January 1, 2015.

What Did We Find?

• We found a total of 9 publications relevant for this review.
• Three cross-sectional studies evaluated the clinical effectiveness of myoelectric prostheses compared to body-powered prostheses. The findings suggested that myoelectric prostheses do not provide additional clinical benefits in physical function, quality of life, or satisfaction when compared to body-powered prostheses for adults with upper-limb amputations. However, the studies had limited internal and external validity, and they were likely underpowered. The study populations consisted mostly of white, male veterans in the US, with potential overlap between some of the identified studies.
• Two systematic reviews evaluated the clinical effectiveness of microprocessor-enabled prostheses (i.e., microprocessor knees) compared to body-powered prostheses. The findings suggested that, for above-the-knee amputations, microprocessor knees provide better or no additional clinical benefits in safety, physical function or mobility, quality of life, and satisfaction versus body-powered prostheses. However, there are many outcome measures used to assess safety and function across the literature, and results conflict depending on the measure used. Manufacturers were also involved in the conduct of 1 systematic review, while the other systematic review reported manufacturer involvement in the included studies.
• We did not identify any studies on the cost-effectiveness of myoelectric prostheses compared to body-powered prostheses for upper-limb amputations.
• One systematic review evaluated the cost-effectiveness of microprocessor-enabled prostheses (i.e., microprocessor knees). It concluded that microprocessor knees are cost-effective compared to nonmicroprocessor knees. However, the findings may not be generalizable to health systems in Canada, and there is considerable heterogeneity in willingness-to-pay thresholds and considered costs across the literature.
• One guideline on upper-limb amputation recommends body-powered prostheses or externally-powered prostheses (including myoelectric prostheses) to improve independence and reduce disability for people with upper-limb amputation (a weak recommendation based on very low certainty of evidence). It did not identify evidence to recommend 1 type over another.
• Two evidence-based guidelines recommend microprocessor knees based on evidence suggesting that they reduce falls, optimize function and mobility, enhance quality of life, and improve satisfaction. However, 1 guideline deemed the supporting evidence to be of very low quality and the recommendation to be weak, while the other guideline lacked a risk of bias assessment. The former guideline also recommends energy storing and return or microprocessor foot and ankle components over solid-ankle, cushioned-heel feet to improve ambulation and patient satisfaction (a weak recommendation based on very low-quality evidence).

What Does This Mean?

• Microprocessor-enabled prostheses, specifically those with microprocessor knees, may provide more or no additional clinical benefits and may be more cost-effective than conventional prostheses for adults with above-the-knee amputations. However, the literature was assessed to be of low quality, with considerable heterogeneity in outcomes. It is unclear how generalizable these findings are to health systems in Canada.
• Limited and low-quality evidence suggests that myoelectric prostheses and body-powered prostheses do not provide additional clinical benefits. Additionally, the comparative cost-effectiveness of these devices remains unclear.
• Evidence-based guidelines underscore the importance of patient-centred care and shared decision-making for people living with an amputation. Clinicians may wish to account for patient factors — such as their activity levels and needs, preferences, and access to rehabilitation services — when prescribing a prosthesis.
• Previous research has identified disproportionately higher rates of lower-limb amputations in remote areas, in neighbourhoods of low social capital or low socioeconomic status, and among Indigenous Peoples living in Canada, due to unmet health care needs. However, inadequate reporting of population characteristics in the included studies limited the ability to make conclusions about the applicability of findings for people with an amputation in these underserved populations.