Stifle Problems, Your opinions.?

I have had my 7 year old mare Since late january, She was trained 2 years of cutting training before her first owners sold her. She then went to a guy who was very interested in cutting and needed a horse to move up a level on so he bought her cause of her fantastic bloodlines. He said that she wasn'tt a high enough cutter for his level. So i bought her cause of her great reining potiential and amazing disposition. Im a 14 year old girl and she is my second horse. A few monthhavinghaveing her her stifle gave out. We have now had it buted TWICE and we think it's getting worse. I would like to know the opinions on the stifle surgery where they go in and clip a ligament around the stifle? I have heard very good and very bad from people who i personally know that have had there own experience. Has anyone had it done before? We have put so much money into her and she is the hardest worker, she would do anything to please and i would just hate to see anything bad happen to her. After the surgery would i be able to do reining or any serious events or would i need to look into another horse? I would love to have you opinions especially if you have had experience with this!