I dont know how to explain it properly in English, Like how you break your knuckles, I could make that same sound in my neck, hips, elbows, feet, ankles, toes and knees etc, name a joint and I can make that sound
My knees, and all my joints make that knocking sound quite often,
Prionation/****ation, what ever is correct spelling, is actually quite big thing.
When I was in army, I rejected support soles, a bad mistake. I had "stress infection" (not sure about correct english term) on both legs for basic training. It took about 26 400mg ibuprofen pain killers to make it through soldiers exam.
If you don't get good shoes you will have complications.