Please Help us help Bella

Bella is in need of knee surgery she has a torn ACL that is very painfull for her but because she is a big dog she has to have a very specific surgery so it will hold which of course is very expense. Bella is a wonderful companion. I rescued her almost 3 years ago for my grandchildren. But she is the greatest all around dog i have ever seen. She has always been so full of life that it breaks my heart that she can no longer run n jump without pain. I have taken her to three different vets. But none of them could help her. The one vets office referred us to an orthopedic specialist who can help but they refuse to let us make payments they want it all. Without this surgery she will never be her self again. When she walks you can hear her knee pop and Crack it sounds awful I know she is in extreme pain. Please help her run and play again. Thankyou.