Three bones make up the knee joint: the end of the thighbone (femur), the top of the shinbone (tibia) and the knee cap (patella). The knee also contains large ligaments, which help control motion by connecting bones and by bracing the joint against abnormal types of motion. The space between the bones is filled with a substance called synovial fluid. Synovial fluid contains hyaluronic acid, which serves to help cushion and lubricate the joint.
When the cartilage between the femur and tibia is worn away – which happens with osteoarthritis – the bones can grind against each other. That grinding can hurt. You may feel it climbing stairs, working in the garden or just bending your knees. The pain may even keep you up at night.
As osteoarthritis progresses, the natural hyaluronic acid found in synovial fluid decreases both in quality and quantity. Therefore, it cannot cushion and lubricate the joint as well.
According to researchers, the link between genetics and osteoarthritis appears to be strong. In other words, if your mother had it, you may be more prone to have it too.1 Other contributing factors may be trauma to the knee, overuse on the job or being overweight. In addition, osteoarthritis can occur when joints are out of alignment, as in people who are bowlegged or knock-kneed.
Moderate Stage Osteoarthritis
Severe Stage Osteoarthritis
A sign of osteoarthritis, or any kind of arthritis, is pain in or around the joint. The pain may be there all the time or may come and go. It often occurs during or after activity or exercise. However, it may also happen after you’ve rested, or even when you are trying to sleep. The pain may be in one spot or you may feel it all over your body. Your joints may feel stiff or become swollen, red or tender.
Osteoarthritis pain in the knee can be treated. Because arthritis may worsen over the years, it is common for treatment to involve more than one approach and to change over time. Although there is no cure, early diagnosis and treatment are crucial steps in managing osteoarthritis knee pain. Together, you and your doctor can determine the best treatment options for you.
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, Department of Health and Human Services’ National Institute of Health (NIH), Handout on Health: Osteoarthritis. May 2006. NIH Publication No. 06-4617. Available at http://www.niams.nih.gov/hi/topics/arthritis/oahandout.htm.