that made the greatest difference in healing it was stretching and loosening of my quads. Getting those muscles to create less pulling and tightness on the connections around the knee caused the patellar tendon to not have so much stress on it when exercising.
I went to a number of physical therapists over a year or so...most did the usual things. But none worked. I finally found Marv Roberson (this was in the early '90s) - he was the trainer who got Bosco held together in the Holiday Bowl in '84. He and his team spent most of their time on my quads getting out knots and getting them loose. It was VERY painful at times...killing knots it my legs with their elbows. But, it worked well.
I was a long, high and triple jumper...and with the tendinitis I couldn't high jump at all. He saved my track career.