My child who is prematurily born of 32 weeks is found having septic arthritis on knee joint. he is on antibiotics from last 13 days and doctors say it wil continue for 8 more days. and after that he has to continue oral medicine for another 3 weeks. x- ray show bone below knee is erroded.after 13 days of medicine he is moving his leg now by own although splint is still there. child is gaining weight.doctors say it will take 3 months for fully recovering of bone. I want to know few things first it is heard most common cause is IV is it true . second , what precaution need to be taken after discharge from hospital. third, he had developed swelling earlier on his leg but USG shows no pus and now swelling has also gone done.so why swelling had occurred.