If injured my lateral collateral ligament what wil the doctor advise? surgery?

Depends: The lateral (fibular) collateral ligament is uncommonly injured, but if it is injured in isolation, it can be treated in a hinged knee brace x 6 wks and may heal on its own. Stress xrays can be used to measure if it heals. This is followed by strengthening and a return to activities between 8-12 weeks. Often, it requires a surgery to reconstruct it and the surrounding "posterolateral corner.".