Understanding how your knee works

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.

Normal Knee

Normal Knee
Bent leg


Moderate Stage Osteoarthritis

Moderate Stage Osteoarthritis
Straight leg


Severe Stage Osteoarthritis

Severe Stage Osteoarthritis
Bent leg


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.


  1. 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.

Indications for use
Gel-One Hyaluronate is indicated for the treatment of pain in osteoarthritis (OA) of the knee in patients who have failed to respond adequately to non-pharmacologic therapy, non-steroidal anti-inflammatory drugs (NSAIDs) or simple analgesics, e.g., acetaminophen.

Important safety information
Before using Gel-One Hyaluronate, tell your doctor if you are allergic to hyaluronan products, cinnamon, or products from birds such as feathers, eggs, and poultry. Gel-One Hyaluronate is only for injection into the knee, performed by a doctor or other qualified health care professional. You should not receive Gel-One Hyaluronate injection if you have a skin disease or infection around the area where the injection will be given. Gel-One Hyaluronate has not been tested to show pain relief in joints other than the knee and for conditions other than OA. Gel-One Hyaluronate has not been tested in patients who are pregnant, mothers who are nursing, or anyone under the age of 21. You should tell your doctor if you think you are pregnant or if you are nursing a child. Talk to your doctor before resuming strenuous or pro-longed weight-bearing activities after treatment. The effectiveness of repeat treatment cycles of Gel-One Hyaluronate has not been established. The side effects most commonly seen after injection of Gel-One Hyaluronate in the clinical trial were knee pain, swelling, and/or fluid build-up around the knee. These reactions are generally mild and do not last long. If any of these symptoms or signs appear after you are given Gel-One Hyaluronate or if you have any other problems, you should call your doctor. Ask your surgeon if you are a candidate and discuss potential risks. For additional information, call 1-800-447-5633 , or visit www.zimmerbiomet.com.

This material is intended for U.S. patients.

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The information herein is of a general nature and does not represent or constitute medical advice or recommendations and is for general education purposes only. This information is not meant to replace the specific verbal and written recommendations and instructions provided by your surgeon for your specific situation. Patient treatment plans and outcomes will vary.

Results may vary.  Not all patients are candidates for this product and/or procedure. Only a medical professional can determine the treatment appropriate for your specific condition.  Appropriate post-operative activities and restrictions will differ from patient to patient. Talk to your surgeon about whether joint replacement is right for you and the risks of the procedure, including the risk of implant wear, loosening, or failure.