What Causes Weakness In Legs After Insertion Of Pacemaker?

My mother is 74 years old and recently was operated for a pacemaker. She starting to feel weakness in her legs, fell down and has a small rupture in her vertebra. However, she was ok using a walker. Now she mentions that her legs do not respond at all. She takes a lot of medications. I have no idea if this has to do with the medications or operation. Please advise