Prepare Your Hip Flexors
The quads and hips are often sold as a pair in the world of training. One important takeaway from that is to remember that the hinge joint in question is usually "prisoner" to the ball and socket joint above it.
Bad elbows usually come from incapable shoulders, and cranky knees are often a product of hip flexors that aren't in the greatest condition. Since the hip flexors – especially the psoas – attach on the spine, they serve a dual role in dictating the health of both the knees and the lower back.
Since most of us live in hip flexion (sitting on our butts), chances are our hip flexors could use an upgrade in tissue quality, which means lacrosse ball rolling, quad rolling, and half-kneeling stretches. They can go a long way in improving the general environment of the thigh and knee.
Again, very simple changes to your warm-up and pre-workout mobility routine may do just the trick. Spiderman walks with thoracic rotation are worth their weight in gold for creating a hip stretch from more than one angle, and the trick is to not just go through the motions.
As far as your workouts, add the half-kneeling position by doing contra-laterally loaded movements. The landmine press is the perfect formula.
Squeezing the glute on the trailing leg can deepen the stretch, making the abs co-contract on the opposing side for stability.