My papa has knee pain when stand but he sit he feel no pain and tomuch swelling.?

Osteoarthritis: Pain when standing usually indicates cartilage damage such as a torn meniscus or more likely wear and tear arthritis (osteoarthritis). The treatment may be very simple such as weight loss, wearing a brace, anti inflammatory medications, etc. I would advise that he get an accurate diagnosis, either from his primary care physician or an orthopedic surgeon.