Thanks for asking query.
Well what you mother is reffering as if feeling of current is going around her legs could be due to some nerve
compression . You havent mentioned clearly what were MRI
findings and what type of arthritis
you mother is suffering from because both the problems arthritis and pin acn be linked also or altogether can be different issues. You are advised to see an orthopaedic surgeon
to rule out any kind of nerve compression . You are also advised to see a rheumatologist
to assess your disease activity pertaining to arthritis .
Wish you good health