As the visitor turned back to face Elaine, his knee suddenly threatened to give way.

She had to go somewhere fast, for her knees were threatening to knock.

His knees trembled, and threatened to give way beneath him.

The knee was threatening to go out on me.

Her knees threatened to give way as she realized what she was seeing.

When he rose, his knees threatened to buckle under him.

His knees threatened to give way as the strap tightened.

He got up but staggered against the console as his knees threatened to give way.

She clung to the rail when her knees threatened to give way.

The man was crying openly now, and his knees were threatening to give way.