Possible Clues:

• As cover for joint, left a special plate on
• Joint cover provided in Asian and American city
• Patrick has the girl on his knee
• Put your bony hand on Ella's knee
• Quietly inform motorists about joint cover
• Bone in knee, head, and everyone's back
• Cap on a leg
• Make a pass at the girl on her knee
• The formal kneecap
• Give the girl a playful knock on the knee