Polycentric Knee Principles

Question 1

The first polycentric knee mechanism was developed at

Answer 1

N/A

Question 2

The instantaneous center of rotation or ICOR derives its name from:

Answer 2

A theoretical center of rotation is present for every possible angle throughout the range of motion available for the knee mechanism. As the knee mechanism flexes in time, the centers of rotation are found for a given instance.

Question 3

Alpha stability is defined as

Answer 3

The posterior placement of the instantaneous center of rotation with respect to the weight line. This value is considered increasingly positive the farther posterior it is located with respect to the weight line.

Question 4

Due to the reorientation of the linkages during flexion of the polycentric knee, the shin segment translates posterior LT; the shin segment rotates differently than it would if it acted about a single axis. This results in:

Answer 4

A relative dorsiflexion of the foot as the knee flexes, which in turn creates increased toe clearance.

Question 5

Due to the changing position of the instantaneous center of rotation, the functional length of the shin segment changes. As the instantaneous center is located more proximally during full extension , the relative shin length is longer.

Answer 5

True