31.   So maybe it was merely flu that weakened him to the point where his knees buckled.

32.   The knee buckled inward when he stepped awkwardly while lunging for first base with his left foot.

33.   The knees buckled on both starting quarterbacks Sunday.

34.   Then his knees buckled, and he began to sob.

35.   To see a knee buckle like that is scary.

36.   Unfit knees buckle at the array.

37.   We were doing a simple passing block drill, and he started to slip and his knee buckled under him.

38.   When Jordan was asked about the changes the Knicks made, his knees did not buckle.

39.   When he tried to move his foot over to the bag, his knee buckled.

40.   When her knees buckled, William Hurt, who plays her husband, involuntarily grabbed one arm and lifted her into his arms.