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Computer-Controlled Prosthetic Legs — An Intro

Posted by Bryan Potok on

Microprocessor technology has been used in prosthetics since the late 1990s with the introduction of microprocessor (MCP) knees or more commonly known as computer-controlled knees. Since then, prosthetic manufacturers, such as Ottobock, Össur, and Endolite, have made continued improvements and added features to make walking more efficient. Today, this cutting-edge technology has expanded to include microprocessor feet.

 An introduction to computer-controlled prosthetic leg systems.

Unlike mechanical prostheses, microprocessor systems are designed to move and even think the way biological systems do. This explains why those who wear microprocessor-enabled prostheses do not need to consciously direct their prostheses during the different elements of walking, including weight-bearing, swinging, or knee flexion. These smart devices make constant adjustments so the user can easily adapt to different terrains.

How Microprocessor Knees Work  

Microprocessor prosthetic knees have onboard sensors that detect variations in terrain and movement. The rich data collected by each sensor is used to adjust multiple times per second the air and fluid cylinder, which allows the computer knee to compensate. These adjustments are made in real-time, which improves the user's mobility and safety over unstable ground. This core feature enables the system to reduce falls or other injurious accidents.

The internal computer is the essential element in a microprocessor knee. It's responsible for making quick decisions based on sensory input. When a prosthetist provides a prosthetic microprocessor knee, they program the computer knee to learn to match the user's gait. And as the computer knee is used, the internal computer monitors every phase of the gait cycle, so it can make adjustments that are minute yet significant.

Microprocessor Knees: Pros  

Because microprocessor knees continuously make adjustments based on real-time data, above-knee amputees report experiencing a smoother gait. Users also report easier and better stability, extension, and flexion compared to other prosthetic knees. The ease of use allows the prosthetic user to enjoy a greater sense of security when walking on various terrains. 

Furthermore, microprocessor knees offer greater control with less effort compared to mechanical knee joints. This is because single- and multi-axis knees require the user to flex their muscles to maintain stability, while microprocessor knees require less conscious thought to initiate changes or control.

How Microprocessor Feet Work  

Prosthetic feet is the latest category to receive a smart, microprocessor upgrade. They, too, have an internal computer that collects sensory input to make minute adjustments in real-time, helping users walk better and easier on incline or decline surfaces. Furthermore, microprocessor feet offer users improved flexion at the ankle joint, thanks to the computer-controlled hydraulic unit.

However, not all microprocessor foot brands can integrate with a microprocessor knee. If you want to use the complete system, make sure that the foot is designed to work with a microprocessor knee or is part of a complete knee and foot system.

Microprocessor System: Cons  

While the microprocessor system is currently the best when it comes to prosthetic joint technology, it still has its drawbacks. Depending on your preference, you may want to consider the following cons before seeking insurance approval.

First, microprocessor systems come at a high cost, which makes them inaccessible to some depending upon insurance and coverage. However, a study published in the Journal of NeuroEngineering and Rehabilitation makes a compelling argument for the high price tag of microprocessor knees. According to the 2018 study, for every 100 persons, prosthetic microprocessor technology resulted in 82 fewer major falls, 62 fewer minor falls, and 16 fewer incidences of osteoarthritis over 10 years compared to non-microprocessor controlled prosthetic legs. Because it results in fewer injuries, researchers said that microprocessor knees reduce direct, as well as indirect healthcare costs.

Second, microprocessor-enabled prostheses tend to weigh more than other types and feel bulkier than a mechanical knee joint. If you prefer sleek and light prostheses, you may want to reconsider. For many users, weight isn't a significant issue because the core features outweigh the weight. Microprocessor knees and feet make adjustments that you would otherwise have to make using additional muscle input. 

Lastly, battery life may get in the way of your daily activities. Depending on how you use it, microprocessor systems require frequent charging.


If you are set on getting a microprocessor-enabled prosthetic leg, consult your primary care physician, physical therapist, and prosthetist. There are many types and brands available on the market today; your healthcare team can help you narrow down the right microprocessor system for you. 

Do you use microprocessor knees and/or feet? Which type and brand are you using? And what has been your experience? Please share your thoughts with the rest of the community below.
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  • Honestly selection depends on how long you’ve been an amputee. I’ve been an amputee my entire life. I got my first microprocessor knee about a year and a half ago. For newer amputees I think it’s beneficial, for veteran amputees its a bit of a nuisance. Though walking has improved, I prefer a hydralic knee. I have more control with a hydralic knee. Inclines, up and down, are tricky with a microprocessor as the knee attempts to brace you from falling and locks up. Stairs are also tricky as the built in fail safes kick in when bending the knee in short spurts and locks the knee. Also, battery charging is terrible. I attended the auto show last year and my battery died. I wound up going home because the knee locked up and wouldn’t move without a charged battery. I get that you have to constantly charge the battery but this is something not needed with a hydralic knee. I will be going back to a hydralic knee on my next prothesis.

    Troy on

  • I got my C-Leg in Sept. 2012. It takes a little to learn how to walk on it.

    charles barnhart on

  • I attempted to get a new leg built (The C-Leg) with the knee processor. I haven’t had a new leg in 28 years and Insurance flat denied me after numerous appeals. I was extremely disappointed. As I get older I am in need more and more for a stable , safe leg. I am a young 62 year old AKA still very active . As I get older a fall could spell real trouble for me.

    Terry Best on

  • Started with my first C-leg about 15 years ago after 30 years with various mechanical knees. The improvement with that very first knee was spectacular. However, I was younger then, and the C-leg was simpler. As the system has grown in complexity with succeeding generations, and as I have aged, I can’t say I’ve seen constant improvement. A microprocessor knee still beats a mechanical knee, but the nuances of fine tuning and occasional electronic gremlins have made it less of a life-changing improvement than that first C-leg was. An interesting comparison study would be to see if electronic knee users become “lazier” as our legs don’t take as much effort to use. In theory, they should allow us to do more.

    Scott on

  • I always wished technology to find ways to improve our lives, invest in humans, a lot more than seeking the unearthly unknown, This leg helps those with AKK since it lot more difficult maintaining balance with those other conventional types Now how affordable are they? of prosthetics,

    Luis Simental on

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