By Daniel Chavkin Nick Piazza, the Saints chain crew worker who suffered two torn ligaments, a fractured fibula and cartilage damage to his right knee in New Orleans’s game vs. the Lions on Sunday, spoke for the first time since the injury. Piazza thanked all the fans who sent home presents and messages, and especially thanked running back Alvin Kamara, who ran into him to cause the injury, for signing a football and jersey as part of the Saints care package. “I really appreciate the messages, care packages and medical treatment,” Piazza said, via Jeff Duncan of NOLA.com. “And if you see Alvin…