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Microprocessors Aren’t Just For Smartphones Any More

There’s no doubt that advanced technology makes the world go ‘round. But self-driving cars and super-computers aren’t the only industries that use high-end tech to keep people moving forward. The orthotic and prosthetic field has made great use of microprocessors to keep patients mobile. They might not move as fast as a Tesla, but they’ll keep moving in more important ways!

Where It All Began

Microprocessor prosthetic knee joints have marked some of the biggest advancements in the O&P field over the last few decades. These advances were giant leaps forward for the industry and our patients.

Traditional mechanical knees utilize several different methods for controlling the swing of the prosthetic limb. Pneumatic and hydraulic cylinders, along with knees with constant friction and even manual locking mechanisms, are used to control the resistance and speed in which the prosthetic knee extends as it takes a new step. Although these knees are still used today and may still be recommended for some amputees, they come with some difficulties. Mechanical knees are often unpredictable for the amputee and difficult to control when walking at various speeds. These functional discrepancies may lead to higher energy expenditure by the amputee while also increasing the risk of a fall.

Enter the microprocessor. The development of some of the first microprocessor knees were aimed at reducing the negative effects of mechanical knees. Early in this technology’s evolution, knees such as the Intelligent Prosthesis from Endolite included a single sensor that detected the moment the prosthesis was fully extended and automatically adjusting knee swing accordingly (3). This sensor allowed the prosthesis to adapt to the amputee’s varying walking speed, giving them more confidence in the prosthesis.

A Great Leap In O&P

While this was a huge leap in prosthetic technology, the introduction of the C-leg from Ottobock in the late 1990s was the first microprocessor knee to control all phases of gait. Sensor data from within the knee was read 100 times per second, adjusting the resistance within the knee in real time (4). These adjustments enabled a feeling of safety in the prosthesis which reduced falls by 64% while also reducing energy expenditure (4). The increase in sensor data influences safety as the knee can offer features such as “stumble recovery” and “natural sitting.” In addition to these features, the knee can be programmed for activities such as biking, golfing, and snowboarding and can be controlled by smartphone.

With the now-widespread use of this technology, most manufacturers have similar microprocessor knees on the market so every amputee can find a knee that works for them.

Although microprocessor knees have been on the market for some time, it was not until the past few years this technology has become available for orthotic patients. Knee-ankle-foot orthoses, or KAFOs, are commonly prescribed for a variety of diagnoses, including spinal cord injuries, stroke, and post-polio syndrome which can all reduce motor control in one or both lower limbs. In these cases, patients are often provided with KAFOs, which stabilize and limit motion of the knee and ankle joints.

These braces are often bulky and heavy, due to being made out of a combination of plastic, metal, and/or leather. Coupled with limited motion, patients often experience unnatural gait patterns while wearing the brace, which causes increased energy expenditure for ambulation and increased wear on other joints in the body.

A KAFO Breakthrough

Very few advances have been made in KAFO technology until recent years, when Ottobock used their microprocessor technology for bracing. The C-Brace is the first microprocessor KAFO, giving patients a lighter and more intelligent bracing option. Similar to that of the C-Leg, the C-Brace controls both phases of gait, giving patients both more freedom and more safety. The microprocessor sensors send data 100 times a second, allowing the KAFO to adjust for every situation (2). Patients can now traverse almost any terrain, walk at varying speeds, and even climb stairs in a more natural manner; movements otherwise difficult in traditional bracing (2).

Like the C-Leg, wearers of the C-Brace also have app-controlled features, allowing them to switch modes for activities such as cycling, or lock the brace for extended standing (1). All These features work together to potentially reduce energy expenditure, and they also reduce physical wear on the body (1).

This technology has been used in prosthetics for some time, but it is in its infancy for orthotics. While the benefits are easily demonstrated, clinical use of the C-Brace is still rare. If you, or someone you know is interested in how this technology can help, contact Tillges today to learn more.



  1. C-Brace. (n.d.). [Online Brochure]. Ottobock.
  2. C-Brace Media Kit. (n.d.). [Slide show; Online]. Ottobock.
  3. Michael, John W. MEd, CPO. Modern Prosthetic Knee Mechanisms. Clinical Orthopaedics and Related Research: April 1999 - Volume 361 - Issue - p 39-47
  4. Williams, W. (2021, October 12). Ottobock C-Leg Bionic Knee. Bionics for Everyone. Retrieved September 9, 2022, from

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