I thought nothing of it at the time, because my knee has straightened after five minutes in the past.

The diver uses it by moving his legs up and down together, letting the knees bend and straighten.

The captain's knees bent a little, then straightened and bent again with a sort of threatening rhythm.

But as the outlaws supported him into the room, his knees suddenly straightened, and she heard him say, "I'll sit over there."

She rubbed stiffened and saddle-galled knees, then straightened her crumpled clothing.

I got my knees straightened finally under me.

His knees straightened, and the drawn sword in his hands hissed.

If I bent my knees, straightened my back and moved slightly forward, balance would come more easily.

Lie flat, bend the knees then straighten the legs upwards so that they are at right angles to your body.

His knees gave slightly, and then straightened.