Can Knee Injury Be Healed By Medicine?

My son fell down from Bike last Monday, as per x-ray; there is air crack side of knee. When I consulted doctor, first he said, no surgery is required, as he is 25 years old, this will joined by medicines. Later when I came to know that he has got Medical Insurance, he is bent upon that surgery after 3 weeks. Now, they have not given any medicines. How any thing can heel without medicines? I start getting doubt about the version of Doctor. Please advice me