http://www.eatmoveimprove.com/2009/08/on-tendonitis/

The thing is there’s multiple ways it forms. Overuse is one, poor biomechanics is another, chronic inflammation of course.

For something like patellar the post above me is correct with anterior chain dominance being the likely culprit. Overuse of the quad leading to chronic tightness, poor mobility, and strong activation patterns at the expense of the posterior chain is very bad.

Since the hamstrings are very weak compared to the quads, most people in the gym and during movements will inadvertently start their squatting, running, etc. all with knee bending instead of proper hip action.

Since they begin with knee bending, the hamstrings don’t receive proper tension and it becomes all quads putting extreme stress on the knee and will likely interefer with proper roll and slide of the joint. This leads to increased clicking/popping/etc. and often tendonitis.

Easily correctable if you know what you are doing. Most knee problems can be solely improved a fair margin with JUST strengthening of the glutes and hamstrings.

Add in soft tissue massage, high dose fish oil for anti-inflammatory, heat to the muscles, ice to the tendon (if it’s -itis) otherwise heat (if it’s osis), and some light eccentric work + other stuff I mentioned in the above linka nd you’re golden.