Detroit Lions receiver Calvin Johnson followed up his record-setting 2012 season with another almost 1,500 yards receiving this year, but it turns out Megatron was in need of some minor repairs. Lions general manager Martin Mayhew said today that Johnson underwent surgery Monday to correct a mangled finger on his left hand. Last week, Johnson had a minor scope on his right knee. “He played the entire season with a finger really that was pointing perpendicular from his body the whole season,” Mayhew said. “He’s trying to catch the ball like that. He would never complain about that, but certainly that was a factor, I think, in the way he played.” Johnson finished third in the NFL with 1,492 yards receiving, but he dropped an uncharacteristic 10 passes. He missed two games this season because of a sprained knee he suffered in September and pulled out of next week’s Pro Bowl earlier this month.