First of all get a X-Ray Knee joint ( AP and Lateral view) of the injured leg.
Get the report and see an orthopedic surgeon.
Meanwhile for symptomatic relief you would need:
1. Anti-inflammatory and analgesic
2. Rest to the part
compression and slight limb elevation to reduce the swelling
4. Avoid weight bearing
5. In case you have bruised your leg you may also need an Tetanus toxoid