But his knees folded under him and he bowed slowly forward.

The man's knees folded, and he fell hard onto the floor.

He sat in the middle of the bed, knees folded like a yoga.

My knees folded and I felt the floor rush up as vision went black.

His knees folded, and he sank in a slow circle to the floor.

When I took a step the knee almost folded.

The tall man's knees folded, and he fell face down.

I felt my knees fold in the wrong direction.

Then things got kind of dim, and my knees folded.

His knees folded and he melted to the floor without a sound.