Hello , I am Dr. Selmani and I read carefully your question. T 12 compression fracture happens from forces when spine bends forward so the purpose of treatment is to immobilize the spine with a brace in a position not to allow the patient to bend forward which may risk the patient to displace the fracture and cause nerve injuries. Usually the principle of these braces is the three point pressure like the tool that bends the wire. The brace should have 2 points of contact forward the body, which one is up in the sternum and one is down in the pubic symphysis in lower belly. The third point is on the back in the level of T12 vertebra that is compressed. The 2 points in front push the 3-rd point in the back of the brace to straighten the spine. Usually the brace should not be high until the chin but until the sternum.If it goes until the sternum you should shorten if possible or go to the ortho technician to repair it. Also your mother should not spend much time sitting in the first 3 months as this is a position that increases the forces of the spine to compress more the fracture. Your mother can do some back muscle strengthening exercises , walking and laying down.and some water aerobic or water gym exercises. I hope she will recover quickly.