Knee Arthritis

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What is knee arthritis?

Your knee plays a vital role in helping you walk and keeps you stable when you stand or squat. It is a weight-bearing joint, which makes it vulnerable to a type of arthritis called osteoarthritis. This type of arthritis is often called degenerative, or ’wear-and-tear‘ arthritis because it results from the wearing away of the cartilage in your joints—most often the hips, knees and hands. With knee osteoarthritis, bone starts to move against bone, causing characteristic arthritic knee pain, stiffness, and reduced range of motion of the joint.

Experts estimate that half of all adults in the United States will develop osteoarthritis of the knee, according to the Arthritis Foundation. Although osteoarthritis is the most common knee arthritis, psoriatic arthritis, rheumatoid arthritis, and post-traumatic arthritis can also affect the knees.

Rheumatoid arthritis is an autoimmune disease that causes your immune system to create painful inflammation in the joints. Psoriatic arthritis affects people with the skin condition psoriasis. Psoriasis is also an autoimmune disease. Post-traumatic arthritis can occur in a joint, years after an injury, perhaps from a fall or a blow to the joint. These injuries can cause the cartilage to wear out more quickly, in case of cartilage damage, or cause unnatural joint movements after an injury.

Arthritis in the knee is painful, but it can affect more than just your knee. The pain can restrict your mobility resulting in limited activity, including social activities. A compensatory gait—walking in a way to avoid knee pain—can lead to skeletal imbalances and chronic back pain. It can affect your sleep, leaving you fatigued, and in serious cases, affect how you perform everyday activities like preparing meals. For people with significant mobility problems due to arthritis, complications can include malnutrition.

Knee arthritis symptoms usually come on gradually, as the cartilage wears away or the inflammation begins. Age is the major factor related to both rheumatoid arthritis and osteoarthritis of the knee, although they can affect younger people as well. To limit the degree of pain, prevent disability, and maintain a high quality of life, anyone with signs and symptoms of knee arthritis should seek medical care.

What are the symptoms of knee arthritis?

Although the different types of arthritis that affect the knee are separate diseases, they have many similar symptoms. However, unlike osteoarthritis and post-traumatic arthritis which can be limited to one joint, rheumatoid arthritis and psoriatic arthritis often affect several joints.

Common symptoms of post-traumatic and degenerative arthritis in the knee

Knee arthritis symptoms include:

  • Pain

  • Stiffness and decreased flexibility

  • Grating or rubbing sensation in the knee when you move it

  • Bone spurs

  • Swelling, more so for post-traumatic arthritis than osteoarthritis

Common symptoms of rheumatoid and psoriatic arthritis

Inflammatory arthritis of the knee also causes pain, stiffness, reduced range of motion, as well as these symptoms:

  • Swelling

  • Redness around the knee

  • Heat coming from the knee

Getting professional medical care when you first notice the symptoms of arthritis can help you get an accurate diagnosis and early treatment, possibly reducing damage to the knee and slowing down the disease progress. In many cases, a doctor can make a diagnosis of knee osteoarthritis based on your symptoms and physical exam, your medical history, and X-ray or other imaging test results. If the case is not clear, your doctor may order blood tests to check for specific markers of rheumatoid arthritis.

What causes knee arthritis?

The cause of knee arthritis depends on the type of arthritis. Osteoarthritis is most commonly found in joints that are used the most, such as the knee. The wear and tear on the joint causes the cartilage in your knee to degenerate and become rough, rubbing inside the joint. With time, the cartilage may wear away completely. Post-traumatic knee arthritis is similar to osteoarthritis, as the cartilage is damaged and wears away. Blows to the knee from contact sports or car accidents are examples of injuries that can cause this type of arthritis.

Rheumatoid arthritis and psoriatic arthritis are caused by autoimmune diseases. Your body’s immune system, which normally guards your body against bacteria and other organisms that can make you sick, begins to attack healthy cells in your body. With some autoimmune diseases, this can cause inflammation in your joints. As the inflammation builds up, it causes pain and swelling.

What are the risk factors for knee arthritis?

The main risk factor for developing arthritis in the knee is age. The exception is psoriatic arthritis, which is caused by psoriasis. It can develop at any age, but it is more common in adults than children.

Other risk factors for osteoarthritis of the knee are:

  • Female gender

  • Overweight or obesity

  • History of knee injury

  • Repetitive stress, such as doing a job that requires you to squat or bend your knees regularly

  • Deformities in your leg bones, which may put pressure on your knees

Other risk factors for rheumatoid arthritis are:

  • Female gender

  • Family history of rheumatoid arthritis

  • Smoking

  • Obesity

Reducing your risk of knee arthritis

While risk factors related to genetic factors like gender and family history are out of your control, you may be able to lower your risk of knee arthritis by:

  • Maintaining a healthy weight

  • Taking care of knee injuries and allowing your knee to fully heal before resuming normal activities  Not smoking

  • Using protective gear when participating in activities that increase your risk of knee injuries

  • Exercising and strengthening your leg muscles so your knees don’t take all the stress, particularly if you must squat or bend them repetitively

  • Following your treatment plan if you have psoriasis

If you show signs or experience symptoms of arthritis in your knee or you have any risk factors for developing arthritis, speak with your doctor about what steps you can take to try to prevent the onset or progression.

How is knee arthritis treated?

Medical care cannot cure arthritis, but active treatment can help you manage arthritis symptoms and perhaps slow down the disease’s progression. There are some differences in treatment depending on the type of arthritis you have, but some strategies overlap. They include: 

  • Exercise and strength training. Building up your leg muscles can help protect your knees and reduce the strain and potential damage to the joint. Tai chi and yoga are often recommended because they do not put extra stress on your joints. They also help improve balance and reduce mental stress.

  • Weight management. Increased weight puts extra stress on your knees, which accelerates tissue degeneration, swelling, and pain. Maintaining a healthy weight may reduce pain and other arthritis symptoms.

  • Physical therapy. A physical therapist can help you regain muscle strength in your legs with special exercises and an at-home exercise plan.

  • Medication. Medicines including nonsteroidal anti-inflammatories can help reduce swelling and pain in your knee. In some cases, your doctor may recommend a cortisone injection in your knee. This will decrease knee swelling. If you have rheumatoid arthritis, a new class of drugs called biologic agents may help control the inflammation in your joints.

  • Artificial joint fluid. An injection of artificial joint fluid—hyaluronic acid—directly into your knee. Hyaluronic acid injections can create a barrier to inflammation and even provide temporary lubrication inside the knee joint, but they are not effective in all patients.

Your doctor may recommend seeing an orthopedic surgeon if the arthritis in your knee is severe. Possible surgical procedures include:

  • Synovectomy. This procedure removes the inflamed joint lining, called the synovium.

  • Osteotomy. This is bone realignment, which may be an option if only one side of your knee is damaged. A surgeon reshapes the bones in the knee to redistribute your body’s weight on the joint.

  • Knee replacement. A partial or total knee replacement removes the damaged knee or part of the knee and replaces it with a plastic or metal joint.

Following a treatment plan for knee arthritis can help improve your quality of life and may slow down the disease process or prevent its complications. Talk with your doctor about the different options that may be available to you.

What are the potential complications of knee arthritis?

Arthritis is a chronic degenerative disease. Left untreated, complications of knee arthritis include increased pain, which can lead to issues like limited mobility and insomnia. Severe knee arthritis can cause disability and inability to work, knee deformity, and social isolation from reduced mobility.

There is also a risk of complications with knee arthritis treatments, such as medicine side effects or surgical problems. As with other health conditions, it’s important to discuss the benefits and risks of available treatment options with your doctor before making a final decision. Many people with knee arthritis respond well to treatment, and the benefits to your health and well-being usually outweigh the risks of not treating the condition.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Aug 21
  1. What Is Osteoarthritis? Arthritis Foundation. http://www.arthritis.org/about-arthritis/types/osteoarthritis/what-is-osteoarthritis.php
  2. Osteoarthritis. Centers for Disease Control and Prevention. https://www.cdc.gov/arthritis/basics/osteoarthritis.htm
  3. Rheumatoid Arthritis. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/rheumatoid-arthritis/diagnosis-treatment/drc-20353653
  4. Osteoarthritis. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/osteoarthritis/diagnosis-treatment/drc-20351930
  5. Post-Traumatic Arthritis. Cleveland Clinic. https://my.clevelandclinic.org/health/articles/post-traumatic-arthritis
  6. Heidari B. Knee Osteoarthritis Prevalence, Risk Factors, Pathogenesis and Features: Part I. Caspian J Intern Med. 2011;2(2):205-212. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3766936/
  7. 25 Treatments for Hip and Knee Arthritis Pain. Arthritis Foundation. http://www.arthritis.org/living-with-arthritis/pain-management/tips/25-treatments-for-hip-knee-oa.ph...
  8. Arthritis of the Knee. American Academy of Orthopaedic Surgeons. http://orthoinfo.aaos.org/topic.cfm?topic=a00212
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