Are you working on it 10-15:00 everyday?
If you are and aren’t seeing improvements you need to relook at how you are addressing it.
Working up/down stream of where you see the issue is key.
Where you see the problem isn’t always where the situation originates.
Have you used a voodoo band on your knee?

Knee Pain? Got Full Knee Power/Range of Motion/Potential–Terminal Knee Extension Part 1
Knee Pain? Got Full Knee Power/Range of Motion/Potential–Terminal Knee Extension Part 2
Knee Pain? Got Full Knee Power/Range of Motion/Potential–Terminal Knee Extension Part 3

When the main engines of the hip or shoulder need attention you can see downstream impact.
The body will make compensations for a time until you hit the tissue tolerance. No warning just game over.