Men and women vary in the range-of-motion of their knees, and there is variation within individuals of the same gender.

An important point of reference is always one's good knee.

(Narration: George Gibb)

 

Take-home messages -

  1. not everyone has the same normal range of motion
  2. always reference to your own good knee
  3. don't aim for just fully straight if your normal knee hyper-extends

Transcript of the video

Here are some photographs of three healthy people - two men and one woman. The woman is the one in the middle. You can see the wide variation, so the quoted ranges for men and women serve only as guidelines.

Note how two of the individuals have such good extension that the knee can actually bend backwards a little bit, and the the heel lifts right up off the bed? This is called hyper-extension, and a few degrees of hyper-extension is normal. The hyper-extension is quoted as a minus number. So, as a guideline, we can say that:​

  • normal ROM in women is usually minus 5 to 143 degrees
  • normal ROM in men is usually minus 6 to 140 degrees

The instrument for measuring range of motion is the goniometer. This is usually made of plastic and is inexpensive. A goniometer is a hinged dial with two arms. The dial is fixed to the one arm. To measure the range of motion, the dial is placed on the joint line while the two arms point to reference points on the hip and ankle. In practice, however, if you do not have a goniometer (and even if you do), a useful measure of the difference between both legs is the distance of each heel from the buttock.

Note how two of the individuals have such good extension that the knee can actually bend backwards a little bit, and the the heel lifts right up off the bed? This is called hyper-extension, and a few degrees of hyper-extension is normal. The hyper-extension is quoted as a minus number.

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