Has anyone had issues with recovery from a hip revision surgery?

My mom has difficulty getting her leg to move when she walks. She had the revision surgery done in January 2013, and went through several months of physical therapy. She walks with the aid of a walker, but has trouble with her mobility in that her operative leg shakes and trembles when she tries to move it. She has a severe limp and says that it feels like she just can get her leg to move when she walks. Her surgeon has indicated that the hip is solid but that there was alot of trauma to the muscle since this is the second operation. We've had her seen by a neurologist who did an MRI of her head and neck but did not find anything out of the ordinary. Any suggestions or information is appreciated.