There is a link for a knee X-ray.?
Well, from the point of view of a non medical individual who is 47 and had both knees replaced coming up on two years ago, that left one looks bone on bone, or darned close, on the medial (inside) aspect. Shes probably in a considerable amount of pain most days. Presumably, since theres an x-ray, shes been seen at least by her primary care physician. Hopefully he or she will refer her to an orthopedic specialist for further diagnosis and treatment. Possibly replacement in the future, though there are things they can try first. As you say she is overweight, it would benefit her greatly to try to lose some of that. My orthopedist had me try to lose 20 lbs (~9kg) before my surgery. It did help, both before surgery, and during recovery. Having built up muscle in the process makes recovery of those muscles easier and a bit faster. Besides, it builds good habits to exercise and do the rehab. If you mother has surgery to help or replace that knee, do try to help her out around the house. Itll be appreciated, even if she doesnt say so.