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The Varus-Valgus-Verifier: V3

Increasing efficacy one trial at a time.

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QuantiPedics is focused on quantifying the effectiveness of Össur's knee braces by measuring the medial and lateral forces in the knee throughout flexion and various varus valgus alignments. As there are no test devices available on the market that model this situation, our goal is to develop this test device; knowledge gained from these tests will help alleviate unnecessary pain from those affected by osteoarthritis within the knee. This project has presented many design and manufacturing challenges; utilizing the diverse background and expertise of our team members, we have steadily approached that goal through multiple research, design, and prototype phases

CAD Assembly

Varus, Valgus, & Flexion

Utilizing a system of pins along the base plate of the feature we are able to achieve a full discrete range of flexion in the knee and varus valgus angles. As seen in the image above there are two pin mechanisms in place to ensure functionality and hard stops between each degree point. The first set of pins in the base plate itself allow for adjustable amounts of varus or valgus flexion within the knee by angling the base ankle mount. The second set of pins rely on the arc fixture on the end of the plate as seen to the left. This arc fixture allows for a hard stop at any of the discrete angles of knee flexion. These two methods allow for not only a precise measurement of the varus valgus angles being affected, but for singular point flexion testing.

CAD Assembly

Knee Backing

The design was developed due to the need to have a flexible, durable and shape retaining knee backing. Throughout the design process the selected concept, a laser cut wooden sheet, was discovered and developed. The patterns within the wood, cut by the laser, allow for different degrees of flexion all while retaining the strength of the backing. Considering the other options for this backing, wood has the most durable standing as we are unable to develop a metal equivalent that wouldn't lead to errosion or be too brittle for the cyclical testing required. The backing of the knee is a laser cut wooden plank that in effect is flexible enough to endure cyclical testing while fixing the pivotal problem of the open back of the knee.

CAD Ankle Assembly


The ankle contains multiple components pivotal to the performance of the overall equipment. The ankle is mobile on two tracks that allow for flexibility. Springs connected to the main ankle cartliage act as the "ligaments" of the system. Without the springs there would be no resistance to the directional changes in the knee. The springs compress and stress the nearby Futek sensors. Working together these components allow QuantiPedics to measure the forces exerted on the knee by the knee brace.