Hi, I had both knees replaced at same time in Feb 2013. Three months later I ruptured my left quadriceps tendon. Two surgeries were done, one at the time it happened & one 6 months later. Unfortunately I still have alot of weakness in that leg over the last 10 years despite those 2 surgeries & many PT sessions!! I've needed to use a walker/rollator to get around. I still keep doing those exercises to try to keep it as best I can. Was told that my situation only happens in 2-3% of cases post knee replacement. And usually up to 3 months post op. Anyway keep up with your exercises and taking whichever NSAID you can to help with inflammation. Best of luck to you!!!