I have tried adding Inverse Kinematics to the legs of my humanoid model using this tutorial: https://www.youtube.com/watch?v=jp_SqjB0468

However, when I move the IK bone, the leg won't bend at the knee for some reason. I have checked the Parenting relationship between the Lower and Upper Leg and everything seems to be in order. How do I fix this so that the leg bends at the knee when I move the IK bone?

Leg doesn't bend at the knee

Here is a link to my .blend project: https://drive.google.com/file/d/1darEP59YbALtv4lqDqYXXS6K270zA3_n/view?usp=sharing


1 Answer 1


In order for the IK constraint to know that the knee is supposed to bend (even with a pole target), it needs to start slightly bent. In edit mode, move the kneecap slightly forward.

enter image description here

Once you've done this, the knee should bend correctly.

Note that if the IK target FootIK is further away from the hip than the ankle is, the leg will be fully extended and the knee will still not bend. Bring the target bone closer to the leg (touching the ankle) to make it bend.

  • $\begingroup$ Thank you! Very simple solution, you saved me lots of time. $\endgroup$
    – SErysuwo
    Dec 1, 2020 at 7:30

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