The Human knee

How does the human knee move? There are two phases of motion – the first takes your knee from fully extended to being bent approximately 90-degrees. The second phase of motion is when your knee moves past 90-degrees until it is fully bent, which
is about 155-degrees.

During this first phase of motion, the knee literally pivots, with the outside compartment of the knee moving backwards more rapidly than the inside compartment. Past 90-degrees, your knee moves backwards evenly, with a combination of rolling and sliding.

Traditional knee
replacement designs

How do knee replacements move? Unlike your natural knee, most knee replacements lack any pivot motion. The movement consists of sliding and rolling through both phases of motion, with only a slight pivot of the outside compartment (rather than the inside compartment like your natural knee).

Also, your knee cap can become slightly misaligned when your knee is fully bent. This makes your quadricep muscle pull at an awkward angle, which causes pain and discomfort.

The JOURNEY* knee

How does the JOURNEY knee move? Just like your natural knee, the JOURNEY knee has two distinct phases of motion—the first takes your knee from being fully extended to being bent approximately 90-degrees. The second phase of motion is when your knee moves past 90-degrees until it is fully bent, which is about 155-degrees.

During this first phase of motion, the knee pivots in a similar fashion to your original knee, with the outside compartment of the knee moving backwards more rapidly than the inside compartment. Past 90-degrees, your knee moves backwards nearly evenly, with a combination of rolling and sliding as your natural knee would.