Step Up Your Lateral Game
Ninety percent of weight training is done in the sagittal plane (forward and backward movement). Only 10 percent is done in the frontal/lateral plane. In English, that means doing lateral (side) movements with load usually takes a huge backseat to common lifts like deads and squats, and it can explain why you're in a world of chronic pain and injury rehab.
For any joint to function correctly, it has to have relative balance between the muscles on both of that joint's sides. Squats, deadlifts, and even split squats have tremendous bang for their buck, but we're tricking ourselves if we think that sagittal plane movements like this are all we need for truly healthy knees over the long term.
Exercises that can take your hip health, knee health, and even lumbar spine and sacral health to the next level are probably the adduction and abduction-based movements that you've been neglecting for years. Here's one of my favorite lateral plane movements.
Side Lying, Leg-Elevated Adduction
This movement combines working the adductors with oblique activation. Don't cut your range of motion short, though.