Not so sure about it actually weaking the connective tissue of the knee. I do know that sometimes the rapid strength gains you get from taking the AAS will overstress the tendons, as they dont have proper time to grow stronger. The connective tissues dont grow nearly as fast, and dont have a good blood supply. I think I might have read somewhere about some AAS weaking the tendons though, might have been winstrol but im very unsure about that. Ive had petellar tendonitis plenty of times, and I usually get it when I am trying to do powerlifting to gain strength. The pounding of that heavy weight week after week adds up and my tendons just cant take it anymore.