Hello Siva, Injury to the knee can lead to fracture of the bones of knee joint, or bleeding in the joint cavity or a soft tissue i.e ligament, or cartilage or muscle injury, all of which will cause pain, swelling and limitation of movement. Analgesics antiinflammatory medicines like ibuprofen acetaminophen combination can reduce the pain and swelling temporarily but if the cause is fracture or deeper bleeding and injury the pain might remain so or even worsen after the effect of medicines are gone. So to be on the safer side, it is advisable to consult a doctor and get a simple xrayof knee joint atleast to rule out any major damage. The doctor may also prescribe a cast or immobilisation or antibiotics as per need. Meanwhile do not bear weight on the affected limb and if possible avoid excessive movement until diagnosis is clear.. Regards