I have really weak knee joints, is there anything i can do to make them stronger and less injury prone?

Yes: Strengthen from "core to floor." work on building core strength, buttock strength, and finally quadriceps (thigh muscle) strength. A common mistake is to only focus on thigh muscle strength, but it is important to start with a strong core and buttock muscles. Also, work on stretching such as hip flexors, hamstring, and Achilles (heel cord).

Strength training: The knee joint can be helped by building up the muscles that cross the joint: quads, hamstrings, calf muscles. The best way is exercise where you recruit most of the muscle (closed chain exercises) such as squats, leg press, cycling etc.