I had a knee injury -- it now hurts to push off knee.?

Need for info: Hard to answer without knowing how you hurt your knee. If you fell or sustained a traumatic event such as a twisting injury, it would be important to be seen soon to eval for a fracture or ligament injury. Without trauma, you have more time to see if it gets better with ice, rest and some anti-inflammatory meds.

Kneecap joint.: You may have irritated the kneecap joint. The discomfort with "pushing off" , would make one think that. But there could be other things wrong. See an orthopedic knee specialist, for an exact diagnosis.