The thought of Sebastian being executed almost made her knees give out.

A dawning understanding, and a wonder that made Cassie's knees feel weak.

Wine has made my knees as unsteady, but I liked the process better.

The implications of what Foster had said hit me hard enough to make my knees go weak.

But if heights make your knees shake, stay home.

She sat down again very suddenly, the reaction from her rage making her knees feel weak.

"The girl whose gaze made men's knees knock," as one rather romantic German paper put it.

Delayed shock hit, making his knees want to come unlocked and spill him to the ground.

A look to make your knees go weak, and - oh, hell - he was coming this way.

But being this close to her made his knees feel loose and uncertain.