'kNEEDING' A RESPONSIVE KNEE

A revolution in microprocessor knee technology keeps amputees moving these days – and at the pace that they desire.

The Plié MPC Knee from Freedom Innovations produces a smooth, secure and natural gait at any speed, angle or incline due to Actuator Response Time (ART) technology. ART uses advanced hydraulic engineering and optimized microprocessor programming to make constant, nearly instantaneous adjustments in response to changes in gait dynamics. Simply stated, the device measures and reacts to gait dynamics in one-tenth the time it takes to blink your eye. The net result is an easier, more natural gait, so amputees can stop concentrating on stability and return to normal activities.

The microprocessor-controlled stance stability and hydraulic swing characteristics enables adjustable stance resistance that enables manual changing from a low-resistant knee for bicycling to maximum resistance for working on an assembly line. The overall design allows the Plié MPC Knee to be water-resistant and is also integrated with wireless capabilities, allowing users to easily set up the knee utilizing bench alignment and manual setting similar to traditional SNS hydraulic knee units, along with simplified, user-friendly software.

However, the knee would not function if the computer-controlled damper inside the Plié MPC Knee did not seal tightly – which is where Trelleborg Sealing Solutions enters the picture.

Trelleborg supplies a range of components for the computer-controlled damper inside the knee. Components include a Zurcon AS Wiper, Zurcon L-Cup, busing, Turcon Slydring and custom FKM (fluoroelastomer) bladder, all ensuring leak-free performance.

The damper in the knee is a monotube with air on one side and oil on the other. Inside, the Zurcon AS Wiper keeps contamination out, while the Zurcon L-Cup is the main rod seal, and the Turcon Slydring is the main piston seal. Absorbing side load, the bushing keeps the rod from hitting the sides of the damper, while the custom FKM bladder forms a barrier between the oil and the air. The result is low friction, with no stick-slip or leakage.

While the wiper is keeping the computer-controlled damper inside the knee contamination-free, the Zurcon L-Cup single-acting rod seal is both an alternative to the U-Cup and a highly-effective sealing system component that delivers optimized sealing performance and extended service life. The L-Cup offers lowfriction, high-wear-resistance, and back-pumping ability, along with high static and dynamic tightness.

The Turcon Slydrings prevents metal to metal contact between piston/ rod and bore/gland, and absorbs transverse loads. The material used for the Slydrings delivers good load capacity with low friction and stickslip- free operation while protecting critical sealing lips from contamination and allowing higher static loads.

Finally, the FKM material used for the custom-made bladder within the Plié MPC knee is a material that provides extended life because of its ability to seal in oily substances.

Additional features of the Plié include a replaceable battery pack – enabling users the option of alternating with a second battery so the knee is never out of working order – and having a user weight rating of up to 253 lb while the prosthetic weighs only 2.3 lb.

Freedom Innovations Inc.
Irvine, CA
freedom-innovations.com

Trelleborg Sealing Solutions
Lombard, IL
tss.trelleborg.com