The Knee That Thinks Ahead: Inside QUATTRO 2’s Real-Time Adaptive Technology
Reading Time: 5 minutes
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Summary:
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QUATTRO 2 microprocessor knee adapts to movement in real time
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Single bidirectional valve and three sensors replace older dual-valve lag
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Processor runs 10x faster than original QUATTRO
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New capabilities include stair ascent, backward walking detection, and independent ramp/stair resistance
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Comes with 20 pre-set activity modes; firmware updates done remotely, no clinic visit needed
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Most microprocessor knees (MPKs) are designed to react. Sensors detect signals from the residual limb, which a processor then interprets and uses to adjust the knee—all within the time it takes to take a step. However, the hesitation most amputees experience happens in the brief moment between footsteps, causing the knee to lag rather than move seamlessly with the user.
PROTEOR, a France-based medical device company that specializes in orthopedics, prosthetics, and orthotics, recently launched its second-generation QUATTRO 2 microprocessor knee to address this gap. According to the company, the new MPK not only detects movement but also adapts in real time. PROTEOR based this redesign on three core principles: motion, adaptability, and proof.
Motion: One Valve, Three Sensors
The QUATTRO 2 is equipped with a patented single bidirectional valve that offers infinitely adjustable resistance with ultra-responsive speed. It uses three high-precision sensors that constantly monitor the system, allowing for real-time adaptive adjustments instead of relying on the step-by-step corrections found in older MPK models.
These sensors are PROTEOR’s fastest yet, up to 10 times quicker than its predecessor, enabling the knee to respond instantly to movement. This means you can focus on living rather than thinking about your knee.
Additionally, the QUATTRO 2 introduces new features, including stair ascent capability and independent stair descent, ramp resistance, and backward walking detection—features that many MPKs still struggle to perform smoothly.
Adaptability: Adapts to You, Not the Other Way Around
The knee’s adaptability is evident in two key areas: fit and daily functionality.
PROTEOR notes that the QUATTRO 2 measures 21.6 cm (8.5 inches), making it “the shortest MPK on the market.” This reduced height enhances compatibility with a broader range of ankles, feet, and running blades, which is especially beneficial for users with limited residual limb length.
In terms of daily functionality, the device offers up to 20 pre-set activity modes, including activities like cycling, golf, and rehab exercises. Firmware updates are conducted remotely, allowing the software to be upgraded without a clinic visit. This marks a substantial change for users accustomed to scheduling appointments for updates.
Proof: Clinical Trial Results
PROTEOR supports its claim of real-time adaptation with a completed clinical trial. The study, titled “Evaluation of a New Microprocessor-Controlled Prosthetic Knee: A Prospective, Multicentered, Randomized Cross-Over Trial,” took place from June 2023 to December 2024 in France. It involved 17 amputees with above-knee or through-knee levels, aged 18 to 85, at the K3/K4 activity level.
Participants used their current MPK for four weeks, then switched to the QUATTRO 2 for another four weeks (or vice versa), and rated their ability to meet personal daily goals on the Patient-Specific Functional Scale (PSFS). PROTEOR reports that on 11 activities—including descending stairs, navigating uneven terrain, water activities, and walking backward—participants scored higher with the QUATTRO 2. The study also showed that users experienced fewer physical limitations with the QUATTRO 2 compared to their usual MPK.
Hardware Improvements
Beyond the software updates, PROTEOR reinforced the frame to support a weight limit of 150 kg/330 lbs, allowing more patients to use it. The knee now has an IP-68 rating, meaning it can withstand rain, showers, and submersion without requiring special precautions. And charging has shifted to USB-C, with a battery life of two to three days per charge and an optional booster cable for longer trips.
The QUATTRO 2, weighing 1,655 g (3.65 lbs), provides 135° of knee flexion. It comes with a 36-month warranty and no scheduled service required, with 2- and 3-year extension options. The device is PDAC-verified under L-codes L5828, L5845, L5848, L5850, L5856, and L5925.
Availability
The QUATTRO 2 is already available in the U.S., with global availability scheduled for September 1, 2026. However, PROTEOR says the date may change.
If you’re considering purchasing one, we advise consulting your prosthetist to ensure it aligns with your activity levels and goals. PROTEOR also provides a trial program for those who wish to test the device before making a commitment.
For more information about the PROTEOR QUATTRO 2 microprocessor knee, visit www.proteorquattro2.com.
Related Reading:
Computer-Controlled Prosthetic Legs: An Intro
Do You Think About Every Step? A Study Looks for a Better Way
Study Says Powered Lower-Limb Prostheses Promote Better Overall Health
Microprocessor vs Mechanical Prosthetic Knees: Which Gives Better Mobility and Value?
