(HealthDay News) -- Knee replacement surgery may be a solution for disabling arthritis, pain caused by other medical problems, or a tumor affecting the knee.

But if you've got certain risk factors, your doctor may advise against the surgery, the U.S. National Library of Medicine says. Here are some examples:

• Having an infection affecting the knee.
• Being morbidly obese.
• Having very weak muscles at the front of the thigh, making it difficult to walk.
• Being severely mentally impaired.
• Having insufficient blood flow to the leg, which could prevent proper healing.
• Having terminal cancer that continues to spread.