One thought about the recipient 'accepting' reiki through the knees rather than the hips. If you consider the esoteric meanings of various conditions - the knees are supposed to hold a lot of 'past' - things that might block one from moving forward - the hips or complaints concerning the hips are representative of 'moving forward' Maybe the recipient needed to deal with the block (knees) before being able to move forward (hips). Just a thought. Nice to see your name here Mamabear.
Love, Light & Reiki Rainbows
Namaste
Eaglestar