Philadelphia 78ers star Joel Embiid suffered an apparent knee injury Saturday and left his team’s playoff game against the Knicks. Embiid injured his knee after an emphatic dunk. After landing, he took a step then stopped and fell to the floor. Embiid made a relatively quick recovery. After heading to the locker room in the second quarter for more evaluation, he returned to action in the third. But NBA fans have a right to be concerned. After all, Embiid tore the meniscus in his left knee on Jan. 30 during a loss to the Golden State Warriors. He had a procedure to repair the cartilage a week l…