Ottobock’s Kenevo knee is the first bionic knee designed for users with lower mobility grades, meaning persons who walk at no more than half-speed, have difficulty overcoming obstacles, and are at a higher risk of stumbling or falling. This knee is exciting because it demonstrates the ability of bionic limbs to adapt to very specific needs.
A Quick Look at the Kenevo
It is not possible to provide a quick general overview of the Kenevo because it can operate in multiple modes and is functionally more like three different knees depending on the mode. Instead, we offer you a glimpse of the type of patient best suited for the knee and its impact on her life:
As explained in the video, this is a patient who had fallen several times with a mechanical knee. Her use of the Kenevo is primarily to ensure greater safety.
Another use-case might be a patient who is recovering from amputation and is undergoing rehabilitation. The Kenevo knee is uniquely suited to this task because users can progress through its different modes. To understand those modes, you first need to understand the knee’s basic capabilities.
Ottobock Kenevo Key Features
General Microprocessor Capabilities
To understand how bionic knees work in general, please see Understanding Bionic Legs & Feet.
The short story is that the microprocessors in bionic knees have three main tasks:
- automatically adjusting the resistance in the knee to ensure the proper level of support through each stage of the Stance Phase;
- ensuring the optimal release point for the knee to begin the Swing Phase, and also the proper foot clearance during this phase, especially when ascending stairs, ramps, etc.;
- assisting in stumble recovery;
The Kenevo offers varying levels of knee resistance depending on the selected mode. It does not attempt to actively control the Swing Phase flexion in any mode but it does actively manage the Swing Phase release point in two of its modes.
To understand precisely what we mean by this, it is best to examine the knee’s behavior in each mode.
Behavior Common to All Kenevo Modes
The Ottobock Kenevo supports a basic set of functions including:
- supported sitting down;
- supported standing up;
- wheelchair function;
These functions are described in the following video:
Mode A: Locked Mode
In this mode, the Kenevo essentially acts like a fixed prosthesis except during the basic functions described in the preceding section.
The purpose of this mode is to ensure maximum safety with no surprises. It is intended for users with less control of their residual limbs who mainly walk short distances indoors and sit.
Mode B/B+: Semi-Locked Mode With and Without Stance Phase Flexion
Both the B and B+ modes release the knee late in the Stance Phase to begin the Swing Phase. They also control the damping of the knee at the end of the Swing Phase. Users require average control over their residual limb to use this mode.
Mode B+ also introduces up to 10 degrees of flexion during heel strike and actively adjusts damping for the Stance Phase extension in real-time.
Mode C: Yielding Mode
In this mode, the knee is no longer locked during the Stance Phase but instead exhibits a high level of damping. Also, the knee is released earlier to start the Swing Phase.
This mode more closely resembles natural walking. It is intended for users who have better control over their residual limb, the ability to handle obstacles like curbs, and the potential to walk step-over-step up and down stairs, ramps, and slopes.
Benefits of the Kenevo’s Design
Quite frankly, this knee has one of the most thoughtful designs that we’ve encountered in bionic limbs. It targets a group of users who need technological help. It is the lightest of the bionic knees, which makes it easier for users to control their prosthesis. And its multi-mode approach makes it ideal for a broader range of use-cases.
The ability to change modes ranging from maximum safety to more dynamic walking is especially useful to:
- accommodate users from a low level of mobility to moderate levels;
- support the incremental stages of rehabilitation for new amputees;
In short, Kenevo’s design appears to fulfill all of its key objectives.
Compatibility with Prosthetic Feet
The Kenevo can be paired with numerous Ottobock feet rated for K1/K2 use, as well the Trias, which is also rated for K3/K4 use.
The Kenevo’s battery can last for up to 24 hours. Ottobock recommends charging the battery each night.
Despite searching extensively for this information, we do not yet know how long it takes to fully charge the battery if it is completely drained.
Water Proofing and Dust Resistance
The Kenevo has an IP rating of 22, meaning it is protected from dripping water but otherwise has little protection against water or dust.
It is best used indoors or in clean, dry environments.
Device Weight & User Weight Limit
The Kenevo is the lightest bionic knee at .92 kilograms. The maximum allowable user weight for the knee is 125 kilograms.
The Kenevo is technically rated for K1/K2 use, though it would be more commonly selected by K2 users. For a thorough understanding of K-levels, please see the Amputee Coalition’s web page on this topic.
In particular, the Kenevo was designed for those with lower-to-moderate mobility, i.e. the ability to walk up to 3 kilometers per hour versus the average walking speed of 6 km per hour.
Ottobock provides a software application for configuring the Kenevo called “K-Soft”, but this appears to be for prosthetists only.
The Kenevo does not appear to utilize Ottobock’s Cockpit Application, which allows users to adjust the settings for all other Ottobock bionic knees.
We have contacted Ottobock for clarification and will update this section as soon as we receive a response.
Ottobock offers a full three-year warranty on the Kenevo including any repair costs due to defects. They also offer a free service inspection in month 24 and a free service unit during repair and service inspections.
The warranty can be extended to six years at the user’s option.
According to our information, the Ottobock Kenevo sells for between $30,000 and $40,000 US including the socket, prosthetic foot, and all prosthetist fees.
Considerations Before Buying a Kenevo Knee
If you are a K2 amputee with low-to-moderate mobility, we think you should move the Kenevo to the top of your shopping list. It is designed specifically for you and Ottobock seems to have done a good job executing that design.
For more information on lower-limb bionics, see Understanding Bionic Legs & Feet.
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