Simulating various patterns of muscle co-contraction to move the knee

Now that the femur of your knee kit is fixed in place, you're ready to start simulating various patterns of muscle contraction to see these affect the knee joint and the motion of the tibia.

An extensor contracting on its own to drive motion

How to attach

You'll start by simulating the contraction of a single muscle on its own to see what happens when muscles don't co-contract (also called co-activate) with other muscles, using the rectus femoris muscle as an example. This  muscle is one of the four quadriceps muscles, which are knee extensor muscles (they extend the knee). To attach the manual muscle cord, follow the steps shown in the video or listed out below.

Video to add: Attaching a rectus femoris manual muscle cord to the knee kit

1. Thread the non-looped end of a manual muscle cord through the hole for rectus femoris in the cross section plate (labeled REF-A).

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2. Pull the cord through enough so that you can insert the non-looped end of the cord through the clip on the rectus femoris tendon (labeled REF-B). Be sure to insert the cord through the labeled side first (i.e., you should see "REF-B" as you're inserting the cord).

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3. Pull the end knot through the clip and slide the cord into the slot on the top of the clip.

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4. Pull the cord back through the clip in the opposite direction, keeping the cord in the slot and allowing the knot to get become hooked inside the clip.

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5. You should now be able to pull on the looped end of the cord (on the other side of the cross section plate), tightening the cord and causing the knee to extend.

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When attaching manual muscle cords, always insert them through the cross section plate first since the knot on the looped end won't fit through the hole.

An extensor and a flexor co-contracting to drive motion

RF+hamstring

Two extensors co-contracting to drive motion

VAL

VAL+VAM

Two flexors co-contracting to drive motion

SEM

SEM+BFE

An agonist-antagonist pair co-contracting to stiffen joint

SEM

Two agonist-antagonist pairs co-contracting to stiffen joint

SEM