We all read about it:
"Bethanie Mattek-Sands, 32, was approaching the net early in the third set of her second-round match Thursday against at Wimbledon when her right leg crumpled.
As her opponent, Sorana Cirstea, walked toward the net to see what was wrong, Mattek-Sands began to shout: “Help me! Help me, please!”
She lay on the court, grabbing her knee, and her wrenching cries pierced through stunned silence across Court 17 and nearby courts. Cirstea stepped over the net, where, she said, she saw that Mattek-Sands’s right knee was 'in a very weird position.'"