Knocked knees are a result of the body trying to find joint actions it is naturally missing in order to complete the gait cycle, or allow for full human movement. This comes at a cost of stressing tissues and joints around the pelvis and knee. To fix it, we should start with the root of the problem – the pelvis in Anteiror Tilt.
If your feet are flat, you are not going to get your arch to “re-rise” without a lot of help, especially from something like an orthodic. Pay attention to your pelvis because it’s a primary factor.
Our brain is seeking stability. But we need to be able to go through the “typical” gait cycle as normally as we can if we are to conserve the most energy. If we lack a range of motion we do not possess, compensations can occur up and down the chain to “find” that range of motion that might be lacking where we need it.