Hi,Welcome to healthcare magic. After going through your query I think You are suffering from osteoarthritis of every. You can not take anti inflamatory due to gastric by pass surgery. Diacerinre and glucosmine sulfate protect cartilage from breakdown and help in cartilage regeneration. Quadriceps exercises is started after pain relief. Serum vitamin D test is advised and if it is low than vitamin D supplementation will be required. You can discuss with your treating doctor. I do hope that you have found something helpful. If you have additional questions or follow up queries then please do not hesitate in writing to us. I will be happy to answer your queries. Wishing you good health. Take care.