Welcome, CarolJose1, I hope you will enjoy GN. I have no experience of your situation, but a neighbour was in a similar position. She managed to lose 2.5 stone on the 5:2 diet and went on to have her hip replacement, making a rapid recovery before having the second one done. She is a determined lady in her 80s, and worked hard at the diet and recommended exercises, which paid off.
I hope all goes well for you. There will be plenty of support on here. 