The Cheetah

From: http://www.ossur.com/

The Cheetah Flex Foot

Fast Facts
Scores of amputee athletes have used the Cheetah Flex-Foot to compete at an international level of sport over the past decade. In fact, it is the gold standard in prosthetic feet for elite amputee athletes. Every medalist in the 100m, 200m and 400m races at the 2004 Paralympic Games in Athens wore a Cheetah. The technology used in the Cheetah Flex-Foot has existed since 1997, and has not experienced any significant updates since that time.

What Is It?
The Cheetah Flex-Foot is a J-Shaped, high performance carbon composite prosthetic sprinting foot, designed to store and release energy in order to mimic the reaction of the anatomical foot/ankle joint of the able bodied runners.

Who Is It For?
The Cheetah Flex-Foot was designed for unilateral/bilateral transtibial and transfemoral (above-the-knee and below-the-knee) amputees who wish to sprint on a competitive and or recreational level.

How Does It Work?
The Cheetah Flex-Foot is a passive prosthetic foot that uses patented carbon technology to efficiently store and release energy produced by the user while running. the shape, which somewhat resembles the hind quarter of a Cheetah -hence the name- acts like a spring and shock absorber. The "J" curve is compressed at impact, storing energy as well as absorbing high levels of stress that would otherwise be absorbed by the user's knee, hip, and lower back. At toe-off, the "J" returns back to its original shape, releasing a percentage of the stored energy and propelling the user forward. The foot is designed to have more layers of carbon at higher stress points, such as the apex of the "J" curve, and less carbon where more flexibility is needed, such as the toe portion. Importantly, the Cheetah Flex-Foot has no heel component. This ensures that the reaction of the foot accurately mimics that of an able-bodied runner by keeping the user on the "balls of their feet," as well as producing a quicker reaction from the loading response as compared to traditional prosthetic feet.

What Does This Mean for the Amputee?
Ultimately, it allows amputee athletes to train harder and longer, which should produce higher levels of performance than those of traditional feet. the smooth reaction and dampening effect of the foot allows the user to focus on the task at hand, and not on what the foot is doing.

Customization of the Cheetah Flex-Foot
The carbon technology is sometimes customized for the user. The thickness of stiffness of the foot is dependent on the user's body weight, residual limb length, and alignment of the foot in relation to their running style. This can help optimize the performance of each individual, as well as improving the durability of the foot. The Prosthetist also has the ability to customize the toe shape and tread plate that is attached to the bottom of the foot. The spike plate of a sprinting shoe or sole of a tennis shoe are applied to the carbon toe to assure traction and conformity to the running surface. Alignment wedges are provided so that the alignment of the foot can be altered even after the prosthesis has been finished.

Is the Cheetah a Bionic Foot?
No. Bionic limbs often incorporate sensors, microprocessors, and motors that have the ability to supply powered movement and responses for the user, based on feedback captured throughout the gait cycle. The Cheetah is a passive foot, which means it is limited to returning a portion of the energy stored during the loading phase of running. Studies have shown the Cheetah can return 90% of the load applied to it. In contrast, a normal able-bodied foot/ankle/gastroc system can return 249%.