You could stop reading now - as you have the news. Everything else is detail.
Above is a random x-ray of a healthy right hip. On Mom's left hip, she sustained a hairline fracture in the little thumb of bone which protrudes from the top rear of the lower, outer sheath. Mom's little thumb of bone appears detached from the lower sheath of her hip bone. In this x-ray of a right hip, you can see such a thumb of bone protruding inwards, near the nine o'clock position - which is why I included this picture. The thumb of sheath bone is attached to muscle.
To the left is a drawing of a healthy left hip. The thumb of bone would be on the back side of the lower sheath of bone - near the three o'clock position in this drawing.
To the left is a cutaway drawing of the metal ball and spike used in a partial hip replacement. The metal ball and spike from Mom's surgery are undamaged, and remain perfectly positioned.
The hairline fractured sheath of Mom's hip has been partially pulled from the bone by attached muscle. Possibly as a result, Mom's left leg might be shorter than her right leg - by less than an inch. She should be able to live with that, with little problem. Possibly as a result, her left leg might be slightly rotated towards the outside, rather than positioned with her left foot and left knee pointed more forward. She can live with this also. It's difficult to say how many degrees her left leg might remain rotated towards the outside. As her muscle tone increases, Mom's leg, knee, and foot might be pulled more towards the front.
There is only the slightest chance the hairline fracture will cause a serious problem. That serious problem, if it arose, would be a new dislocation of her left hip, caused by a lack of muscle support to the area.
We did not know, until today, that Mom's hip had a hairline fracture. The ER Doctor missed the fracture on the post-fall x-ray. Mom saw her Orthopedic Surgeon today, and he saw the fracture. Hopefully, this will merely be a blip, as Mom has been walking further and further distances since the fall. She is currently travelling 400 feet per day(editor's note: not 400 at one time, as I originally wrote). Insert your own sports analogy in the comments below.
Previous to the fall, I had been a pest about hip precautions. Mom had not been happy to be pestered. After her fall, as she lay on the floor, Mom's first thought was "I can't believe I did this". Her second thought was "I hope Greg doesn't find out."
Pate Rehab now keeps someone in Mom's Sitting Room all during the night, to ensure that she doesn't get up, and try to walk, without supervision. Mom is strong enough to rise and walk on her own. Since her balance is imperfect, she needs her walker, and some supervision.