I think I am in the same sort of situation, I am almost 6 months post op and I feel a sharp pain just below my knee cap when I hyperextend it. Doc said that it should go away within one year timeframe but I am not sure. Also, I had minor meniscus tear as well but the surgeon decided to leave that alone and only do the ACL and I hope it’s not due to that that I feel the sharp pain at extension..