Hello, According to the symptoms you have described, there seems no relation to your knee pain and the surgery you had had at the age of 35 years. It seems that you are suffering from osteoarthritis. Our knee joint is the joint that joins thigh and leg bones with each other. It is a hinge type of joint and works as any other hinge. In this joint, the bones of thigh and leg are joined with each other through a cushion like disc in between them. This disc absorbs shock, lubricates the joint and makes the movements of the knee easy. As the person ages, the disc degenerates slowly up to the point that the bones of thigh and knee feel friction while they come in contact with each other during movements. These movements are leg flexion and extension, the movements that you described you have trouble with. This osteoarthritis usually starts in people of age 50 or older, but because you have spent most of your life doing activities that give exercise to your body and joints, it has started at the age of about 75. To confirm the diagnosis, you can go to an orthopedic surgeon. He may take an x-ray of the knee joint and confirm the diagnosis by amount of degeneration x-ray shows. To find relief from the pain, you can take painkillers available over the counter like Ibuprofen 400 mg two times day (if you are allergic to it or asthmatic, avoid it) or Paracetamol 500 mg two to three times of day (avoid in case of allergic to this medicine) when needed. You can consult a physiotherapist to show you some exercises that can help in reducing the speed of degeneration. If you find that the pain is limiting your day-to-day activities after some years, you might have to go for knee replacement surgery. I hope this information helps. Thank you for choosing HealthCareMagic. Best, Dr. Viraj Shah