Surgery Fail...Frustrated

Gracie has a luxating patella which basically means her knee cap slides out of place.  Surgery is the only way to fix it.  Not fixing it means pain and arthritis when Gracie is on older girl.  After saving $2500 (ouch), she had surgery a week ago.  Things were going well and then yesterday, her knee cap slid over.  It did it twice yesterday.  I called the vet and they said to keep her crated except for pottying and to bring her in early next week.  Today, it slipped out when Dan was walking her in a straight line on carpet out of the house to potty.  It was HARD to get it back in.  It slid out again while she was outside again walking on a relatively flat surface.  I'm so discouraged.  Not only does it feel like we wasted a ton of money, but it feels like the problem is worse :(.  Would you pray?