Advanced Knee Replacement

The Advanced Knee Replacement is a technique used by Aperture Science to prevent their Test Subjects from suffering from huge drops by lessening the impact. It consists of two prosthesis completely or partially replacing the knee, partially tied to the Test Subject's calves, and prolonged with two flexible bars going under the Test Subject's heels, acting as springs. As the only seen Test Subject, Chell uses these prosthesis.

Behind the scenes

 * The heel springs were originally created for the Combine Assassin, cut from Half-Life 2.


 * The Advanced Knee Replacement was added into Portal due to disbelief by playtesters that Chell could survive the drops she was subject to, particularly those that involved falling recursively through portals.


 * According to Matt Charlesworth, the team is not sure whether to keep the Advanced Knee Replacement in Portal 2. He states that some team members are attached to it, and that some are not, so they have experimented what to do with them, or how to replace them.

Trivia

 * The real-life corollary activity to this is called "powerbocking". A very similarly shaped device is also used as prosthetic legs for amputees (this is what Eli Vance uses).


 * The sound files for the Advanced Knee Replacement footsteps use the name "future shoes."

List of appearances

 * Portal
 * Portal 2