What Is The Remedy For Lipoma On Lower Lumbar With Growth Around Sciatica?

Girlfriend has herniated L4 disc, her left hip is a partial replacement at top joint. She also has very large lipoma on lower lumbar with growth around her sciatica and it is affecting circulation in left leg and foot. Circulation is horable almost non exsistant. We have ben told if it gets worse she could lose left leg. Afraid to have lipoma removed because of the damage that could be caused to her sciatica if a mistake is made. Something has to be done before anything happens or it gets worse on its own. Very concerned about loosing leg or ending up in a wheelchair for life?