Help get nana a new knee so she's not in pain anymore!!

Our nana used to be able to go walking with us and she loves gardening and teaching us baking and even having messy slime fights, but for the past three years she hasn't been able to do these things very much. She has a very sore knee, so bad that some days she can't even walk but she just pretends it's not that sore and tries anyway. Somedays she cries because it's so sore, but she still says she ok and tries to do everything like she used to. She has been seeing the doctor for ages. They said she had to lose weight so she exercised heaps and that made her cry but she still did it and lost weight. Now the doctor says she's too young to go on the waiting list so she has to wait. We don't want our nana to be sore anymore. We think she should have a new knee so she can go for walks with her new grandchildren and teach them about gardening and slime fighting just as she taught us. She works really hard as a preschool teacher and she is studying full time as well as working full time so she can be a qualified teacher. It would be nice if she could do the things she used to, and to do all the things she wants to with the little children at her work but she can't when her knee hurts so much. Our family is all helping to find money and we are too. We are having garage sales and selling our stuff, we are forfeiting our Easter and birthdays to give that money to Nana and doing jobs to earn money to help nana get a new knee but we would really appreciate some more help