Not for everyone from my understanding. For some folks it's primarily in the back. I'm similar like you and have it in my knees, hips. Elbows, Hands, neck, hips, back... You get the idea. Unfortunately it's impacted my sleep so my Rheumatologist says it has induced fibromyalgia.
Yes in my case all joints I have polymaalger as well but yes hips knees etc hope u feel releif soon xxxhugs