Extension means 'straightening'.

Page updated July 2023 by Dr Sheila Strover (Clinical Editor)

range of motion

A normal range of motion at the knee includes flexion, extension and a small amount of hyperextension. When the knee is straight it is said to be extended. 

Full extension is generally quoted as 0 degrees but may normally be as much as -6 degrees, which is very slightly bent backwards.


Is it important to regain full extension?

It is more important to regain full extension than it is to regain full flexion.

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What is passive extension?

Passive extension exercises, such as 'prone hangs' use gravity to help regain extension.

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Active extension exercises

Active extension exercises rely mostly on the quads muscles, but these muscles often become inhibited after knee injury or surgery, and it may take time to get the muscle to start triggering. Usually one begins with 'short arc extensions'.

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