Power Knee
The Power Knee is a motorized battery-powered transfemoral prosthesis for above-knee amputees that features a set of sensors located on the sound leg. The on-board artificial intelligence module continuously receives data from the sound leg sensors, interprets the information and sends commands to the motor of the prosthesis to generate synchronized motions that will allow the amputee to perform gait in a more natural fashion.
The Power Knee is currently distributed in the U.S. and European markets with the collaboration of Victhom’s business partner Ossur hf. (www.ossur.com), one of the world leaders in the field. The Power Knee has been invented by Stéphane Bédard, founder and Chief Operating Officer of Victhom’s Biotronix Division. Victhom is responsible for the development and technical improvements of the Power Knee, whereas Ossur is in charge of marketing the product.
An above-knee amputation procedure removes two joints (ankle and knee) and a significant part of the thigh’s musculature that a normal person uses to perform various locomotion portions such as level ground walking, climbing and descending stairs, etc. Using standard prosthetic technology, amputees compensate for these absences by developing various strategies such as hip hiking, which generates lowered locomotion speed, a characteristic non-natural gait and, most importantly, harmful consequences such as considerable fatigue and recurrent stump pain and injuries.
Over the years, many kinds of leg prostheses have been devised in an effort to replace the leg or legs that amputees have lost. All these leg prostheses have the difficult task of promoting to these amputees gait that is as natural as possible. However, the complexity of human locomotion is such that, until now, conventional leg prostheses have only used passive mechanisms, where “computerized” passive leg prostheses are still considered by the market as the most sophisticated available devices. The performance of conventional leg prostheses is very limited compared to a real human leg and some needs were thus not entirely fulfilled by them.
According to amputees, specific conditions of use of conventional leg prostheses, such as repetitive movements, continuous loading and assisted mobility from the amputee, typically entail problems such as:
- increased metabolic energy expenditure;
- increased socket pressure;
- reduced locomotion speed;
- discrepant locomotion movements;
- disrupted postural balance;
- disrupted pelvis-spinal column alignment; and
- increased use of postural clinical rehabilitation programs.
About energy expenditure, the energy used for moving the prosthesis mainly originates from the amputees themselves because conventional leg prostheses do not have self-propulsion capability. This has considerable short and long-term negative side effects. Recent developments in the field of energy-saving prosthetic components have partially contributed to improve the energy transfer between amputees and their prostheses.
The Power Knee has become the world’s first leg prosthesis that allows the user to perform advanced gait patterns such as step-by-step stair climbing or standing up on both legs. Specifically, the Power Knee provides users with the necessary locomotion patterns for conventional daily activities such as ground level walking, stair or incline ascent/descent, and sitting down or standing up on two legs. Whereas the mobility of the prosthesis is fully synchronized with the user’s intentions, the Power Knee has a top walking speed of about 7 km/h (4.4 mph) depending on the user’s ability.
In summary, the Power Knee and its artificial intelligence module provide significant clinical benefits to amputees, including:
- Allows walking faster without increasing fatigue;
- Restores dynamics for level ground walking;
- Provides capability to climb a flight of stairs foot over foot;
- Provides powered assistance while walking up steep inclines;
- Allows sitting down and standing up from a chair more efficiently;
- Reduces pressure at the stump and skin injuries;
- Ensures natural gait which provides a normal posture and a significant reduction of back pain incidence;
- Increases the overall locomotion speed;
- Ensures capability to perform tasks previously impossible such as climbing stairs naturally.