Suggest Treatment For Knee Injury

Hi... Yesterday, I hyperextended my knee while playing sports. I received a direct blow to the kneecap and am currently in a knee brace and on crutches. Today, i took the brace off to relax my leg and noticed that if i try to raise my injured leg inward (to make the shins cross) my knee cant support the weight of my shin and foot. I was wondering if this might be a symptom of an acl tear or something else. What could it be?