Can Damage Be Caused If Boot Is Not Used After Heel Fracture?

My Autn who is 88 yrs old has just suffered a heel fracture. Dr. has put her on instructions not to walk on the foot, even the toe part with out the large boot. She is supposed to have it on at all times when walking. She has taken it off and feels that she can walk with limping on the toe area. Can she cause more damage to her fracture by not using the boot for walking even a for a short distance? She has severe osteo. Thanks for your help.

Trisha