You should not get kee problems from walking. Maybe your gait is somewhat unnatural?
Fortunately I never had problems like that but I am sure using barefoot shoes (Fivefinger in my case) improved how I walk. When I am not using those I use zero drop Trailrunners (Altra Lone Peak) which kind of force you to use your front foot more.
I can walk all day on reasonably level terrain with no knee issues. I prefer poles when there is appreciable climb and I absolutely must have poles and compression sleeves on my knees for any substantial descents.
I always hike with poles but if the terrain is level enough they'll be simply in one hand or possibly stowed on my pack. If I'm on a mountain I'll be using them frequently.
