You'll need to check with your doctor on this one. X-rays often tell the story. There could be another fracture causing more weakness of the spine. Just the weight of your mother's body can be enough force to break another bone if she's extremely osteoporotic.
Many patients who have post taumatic deformity (PTD) didn't follow their doctor's advise. The didn't perform the exercises and stopped wearing the brace. Failure to take the medication is also a possible cause of the symptoms getting worse.