I'm sorry you and your family are in such an unenviable position and facing a decision which we all dread.
It might be worth your time to explore in detail with an orthopaedic surgeon, the type and number of the surgeries your puppy will need over her lifetime and the potential for success for each of these surgeries and balance that against her and your quality of life. Some of the folks here who are involved in rescue may be able to best advise you on the chances of a successful adoption with a family who is able to afford the series of surgeries your puppy will need.
But at the end of the day only you know what you can live with and I guess that is the decision isn't it ?
