Advanced Knee Replacement
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|Advanced Knee Replacement|
Prosthetic heel springs
- The device consists of two prostheses completely or partially replacing the knee, partially tied to the Test Subject's calves, and prolonged with two flexible curved pieces of metal going under the Test Subject's heels, acting as springs.
- Before being first awoken, Chell had been fitted with Advanced Knee Replacement, which was destroyed when she got dragged by the Party Escort Bot after she defeated GLaDOS. After being awoken again by Wheatley, she donned Long Fall Boots instead.
 Behind the scenes
- The Advanced Knee Replacement was added to Portal due to disbelief by playtesters that Chell could survive the drops she was subject to, particularly those that involved falling recursively through portals. The Portal trailer, "Orientation Video no. 1", predates this development phase, as it states that jumping from high ledges is fatal if a portal is not below.
- The Advanced Knee Replacement design was recycled from that of the Combine Assassin's heel springs, the female Combine unit cut from Half-Life 2.
- According to Matt Charlesworth, the team was not sure whether to keep the Advanced Knee Replacement in Portal 2. He stated that some team members were attached to it, and that some were not, so they experimented what to do with them, or how to replace them, until they decided to replace it with a variant, the Long Fall Boot.
- The real-life corollary activity to this is called "powerbocking". A very similarly shaped device is also used as prosthetic legs for amputees (such as Eli Vance's).
- The sound files for the Advanced Knee Replacement footsteps use the name "future shoes".
 Portal 2
Concept art for different Advanced Knee Replacement iterations, revealed during the PotatoFoolsDay ARG. Several of these designs would be the basis for the Long Fall Boot that would later be used in Portal 2.
Outfit study for Chell on a picture of Alésia Glidewell, revealed during the PotatoFoolsDay ARG, featuring several Advanced Knee Replacement iterations.
Pink Advanced Knee Replacement on Mel's placeholder model.
 List of appearances
- Portal (First appearance)
- Portal: First Slice
- Portal: Still Alive (Non-canonical appearance)
- PotatoFoolsDay ARG
- Portal 2: Lab Rat
- The Final Hours of Portal 2