Hi, thought I’d introduce myself, I’m Loz and I own 3 dogs, a 14yr old Jack Russell, an 8yr old collie X and a 6mnth old red merle border collie who will be starting agility soon. I work in a veterinary practice and have been a dog groomer for nearly 20yrs now.
My question is to anyone who has had a dog with a luxating patella, my 8yr old has a grade 4, has anyone had or got a dog that has had surgery for this, and how much of a success was it? Just weighing up wether to get it fixed or not. 
Hello and welcome to the forum. I cannot help you with the decision about luxating patella as none of my dogs has suffered with this. I have had three dogs that needed cruciate ligament surgery. I appreciate that this is different but it is orthopaedic surgery and probably requires the same type of care. I had all of them operated on as soon as possible to save the joint from damage and subsequent arthritis. I also had it done for pain relief. All did very well and did not require ongoing medication. From this experience I would say that good post operative care is very important.
Hello and welcome to the forum. I did once have a read up on this as I have a terrier who hops. She does not seem to do it as much these days thankfully and the vet thinks her patella are okay. From what I can remember when researching, it is one of those conditions which should be monitored and treated according to severity.
If I recall once it gets to stage 4, surgery is required as it will be painful for the dog. Your vet should be able to advise better as beyond some research on the web, I do not have any experience with this condition. I would advise speaking to the vet ASAP though. As with the cruciate ligament problem, which Dottie’s dogs suffered from, delaying surgery could cause more complications. Good luck.