Help Sammy get new knees

Sammy is one of 4 colony kittens trapped and successfully socialized. They were born under an abandoned vehicle in Van Nuys. I currently still feed this colony in a secret location after TNR for 8 cats of this particular colony. It was particularly hard to let go of any of the kittens but I also have 3 adult rescues. All from the streets of LA . Sammy melted our hearts and I chose to keep him.
Sammy is the only one diagnosed with patellar luxation grade 3 and grade 4. He is less then a year old. It is usually found only in small dogs. It basically means he needs new knees for any quality of life at all. I am unemployed for 10 months now and cannot afford this surgery but will do what I have to do to get it done. The picture is how Sammy copes, he lays down to drink as his knees cause him discomfort. I really want him to be free of pain and have a better quality of life. Its going to be long cage recovery but we all feel will eventually allow him a greater quality of life. Thank you for any help you can give.