6 weeks ago got pat tendonitis left knee now only tight pain while on run on treadmill is it safe to start run outside or can I cause more damage?

Start slow outside. Patella tendonitis can be a chronic problem and hard to get rid of. It usually takes backing off from the activity that caused in, relative rest then going back to activity slowly and in increments. If you can run on the tredmill with no problem you can start outside , best would be on a perma-traack like one found at a local high scjool or college. Th surface is level and more cushiony.