Hi. I am a 25 year old female. In an accident in 2010, I suffered from displaced fracture of tibia , right in the middle of the bone. Doctors inserted a nail that runs throughout the tibial bone. 2 years after the accident, I still feel a clear cracking sound in my knee whenever I squat, bend, climb stairs or bend my legs. There is no pain though. The nailing in tibia is still there. Is the cracking sound in knee normal?