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Arthritis of the Knee

Last updated April 18, 2018

Approved by: Krish Tangella MD, MBA, FCAP

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Arthritis is a disorder characterized by an abnormal inflammation that affects the knee joint.


What are the other Names for this Condition? (Also known as/Synonyms)

  • Degenerative Osteoarthritis of Knee
  • Inflammation of the Knee Joint
  • Knee Arthritis

What is Arthritis of the Knee? (Definition/Background Information)

  • Arthritis is a joint disorder characterized by an abnormal inflammation that affects one or more joints, within the body. Generally, arthritis increases with age. The majority of individuals who develop the condition begin experiencing pain and stiffness, in the affected joint or limb
  • Arthritis of the Knee affects the knee joint; especially the cartilage, bone, soft tissue surrounding the joint, muscles, and tendon
  • There are many causes of Arthritis of the Knee. Major causes are: Degenerative osteoarthritis, post-traumatic arthritis, avascular necrosis, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and gout (gouty arthritis)

There are several different types of arthritis. The most common types of Knee Arthritis that may develop include:

  • Degenerative Osteoarthritis of Knee: It is the most common type of arthritis. Osteoarthritis is characterized by a progressive degeneration of cartilage, bones, or synovial membrane, within the joint, usually over a prolonged time period
  • Post-Traumatic Knee Arthritis: It is a type of osteoarthritis. Post-Traumatic Knee Arthritis is a progressive, degenerative disorder that may develop after a significantly traumatic injury to the knee
  • Avascular Necrosis of Knee: Avascular necrosis of knee occurs when blood flow to knee joint is disrupted. This results in tissue damage (of both the bone and soft tissue surrounding the joints). Common causes of avascular necrosis include, chronic steroidal therapy, sickle cell disease, and trauma to the joint
  • Rheumatoid Arthritis involving Knee: Rheumatoid arthritis is an autoimmune systemic inflammatory condition that may affect the lining of joints, surrounding tissues, or organs, within the body
  • Systemic Lupus Erythematosus causing Knee Arthritis: Systemic lupus erythematosus is an autoimmune systemic inflammatory condition that occurs when an individual’s immune system creates antibodies that accidently attack healthy tissues and organs within the body
  • Gout involving the Knee Joint: A complex type of inflammatory arthritis, gouty arthritis is a medical condition caused by a high level of uric acid within the blood. A gout attack occurs with the abnormal formation of crystallized uric acid, resulting in inflammation of the joints. Gout generally affects small joints of the foot. Involvement of the knee joint by gout, is not common

Who gets Arthritis of the Knee? (Age and Sex Distribution)

  • Individuals of all age, race, or ethnic groups, and belonging to any gender, may develop Arthritis of the Knee
  • However, a high percentage of individuals who develop Knee Degenerative Arthritis causing a debilitating and progressive disorder, are middle-aged and elderly adults
  • Young athletes, who sustain traumatic joint injuries while participating in rough or high-impact sports, may develop Post-Traumatic Knee Arthritis

What are the Risk Factors for Arthritis of the Knee? (Predisposing Factors)

Risk factors associated with Arthritis of the Knee include:

  • Age: Degenerative Osteoarthritis of the Knee may develop in individuals of all ages, but is rarely diagnosed in individuals under the age of 40 years. However, since it is a gradually progressing disorder, the risk of developing this condition usually increases with age
  • Gender: Degenerative Osteoarthritis of the Knee and rheumatoid arthritis are more likely to develop in women. However, men have an increased risk of developing gouty arthritis
  • Athletics: Individuals who sustain a knee joint injury while participating in a rough or high-impact sports, such as football, basketball, soccer, wrestling, rugby, hockey, skiing, and snowboarding, are prone to developing Post-Traumatic Knee Arthritis
  • Obesity: Excess body weight associated with obesity may cause abnormally increased pressure on the joints. This increases the risk for degenerative osteoarthritis, affecting the knee
  • Family history: Some arthritic disorders, such as rheumatoid arthritis, have a genetic prevalence. Those having an immediate family member or a relative with a history of rheumatoid arthritis condition, may be at increased risk
  • Smoking: Various studies have found that smoking is one of the key contributing factors for the development of rheumatoid arthritis
  • Certain occupations: Individuals with certain occupations (like carpenters and painters), which require a set of repetitive physical movement/motion for prolonged periods, have an increased risk of developing Degenerative Osteoarthritis of the Knee

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Arthritis of the Knee? (Etiology)

Many different contributing factors exist, since there are several different types of arthritis. Some causes that may be associated with Arthritis of the Knee include:

  • Sports-related injury: Post-Traumatic Knee Arthritis may develop in individuals who sustain a joint injury, while participating in rough or high-impact sports, such as football, basketball, soccer, wrestling, rugby, hockey, skiing, and snowboarding
  • Certain occupations: Individuals with certain occupations that require a set of repetitive physical movement/motion for prolonged periods, such as carpenters and painters, may be affected by Degenerative Osteoarthritis of the Knee
  • Family history: Some arthritic disorders, such as rheumatoid arthritis, have a genetic prevalence. Those having an immediate family member or a relative with a history of this condition, may be at risk
  • Obesity: Excess body weight associated with obesity, may cause abnormally increased pressure on the joints

In all of the above cases, the cartilage tissue covering the joint is damaged, either due to inflammation (such as rheumatoid arthritis), or due to repeated stress/trauma (such as degenerative osteoarthritis). The thinning of cartilage causes bone-on-bone contact in the joints. Once the bones are rubbing on each other, it causes pain, stiffness, and abnormally restricted joint movement           

What are the Signs and Symptoms of Arthritis of the Knee?

Arthritis is a gradual and progressive disorder that usually worsens over time. Common signs and symptoms associated with Knee Arthritis include: 

  • Noticeable pain and tenderness (pain on touch)
  • Swelling of tissue (due to inflammation) around the knee joint
  • Stiffness, decreased range of motion of the knee joint
  • Knee joint deformity
  • Noticeable redness due to an inflammatory response of the body

How is Arthritis of the Knee Diagnosed?

Diagnostic methods that a physician may use to help diagnose Arthritis of the Knee include:

  • Physical examination: A thorough physical examination of the knee may be undertaken by the physician. In addition to this, a complete medical history will aid in arriving at the correct cause of Knee Arthritis
  • X-rays: X-rays are utilized to visualize images of the knee. It can also help the physician rule out other possible causes for knee discomfort
  • Blood Test: A blood sample is drawn from an artery or vein using a needle and taken to a laboratory for analysis. Blood tests such as Complete Blood Count (CBC), Rheumatoid Factor (RF) levels, cultures of the joint fluid, Lupus blood tests (SLE panel) help the provider arrive at a cause for knee arthritis
  • Fine needle aspiration (FNA) of joint fluid analysis: Occasionally, fluid may accumulate around a joint, which results in pain and disability. Analysis of this joint will provide clues regarding the cause of joint fluid accumulation
  • Ultrasound imaging: An ultrasound imaging equipment uses high-frequency sound waves to generate a more detailed image of the knee
  • MRI and CT scan of knee joint: This helps assess the damage to the joint and surrounding tissue.
  • Arthroscopy: During this procedure a surgeon inserts a thin tube attached to a camera (a fibro-optic camera) into the joint, via a small incision on the skin of the joint. Visualizing the joint via a camera helps the healthcare provider arrive at a cause of Knee Arthritis. Arthroscopy is considered to be a minimally invasive diagnostic tool

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Arthritis of the Knee?

Arthritis is a progressive condition that gradually worsens over a long period of time.  The complications from Knee Arthritis include:

  • Chronic pain and stiffness within the knee joint, which may prevent individuals from performing their routine daily activities
  • Some cases may cause permanent disability (frozen joints)

How is Arthritis of the Knee Treated?

The treatment measures depend on the cause of Knee Arthritis and these are grouped as non-surgical and surgical treatment methods. A healthcare provider may start with non-surgical treatment methods before adopting surgical procedures and techniques. However, in some cases, the healthcare provider may elect to use surgical treatment methods, if the symptoms or the condition, cannot be managed with conservative non-surgical methods.

Nonsurgical treatment measures that may help relieve pain and improve range of motion of the knee joint include:

  • Rest: Any activity that aggravates the knee condition further should be avoided. The physician usually advises to refrain from all such activities, until the symptoms stop
  • Heat and ice: Applying a damp heated towel or ice to the knee joint, can help reduce pain and swelling
  • Splint or brace: Some type of padded splint or cast may be used to help keep the knee joint in a stable position, especially while sleeping
  • Non-steroidal anti-inflammatory medication: Oral medications, such as ibuprofen and naproxen, can help decrease pain and swelling in the knee
  • Corticosteroids: Oral steroidal medications, such as prednisone, may help decrease inflammation and increase motion range of the knee
  • Viscosupplementation therapy: The normally present fluid (synovial fluid) within a joint contains a material called hyaluronic acid. When a joint is affected by osteoarthritis, there is a reduction of hyaluronic acid level within the joint. This decreased acid level reduces the fluid’s ability to lubricate the joint. Viscosupplementation is a common and minimally invasive technique that is used in treating osteoarthritis. During this procedure, small doses of hyaluronic acid are injected into the knee joint, to increase its lubrication and thereby relieve pain
  • Physical therapy: After the signs and symptoms have decreased, it is important to begin some light motion exercises. Physical therapy may help restore strength, as well as flexibility, in the muscles
  • Injection of steroids into the joints: Steroid injection into the joint helps in temporary relief of symptoms (such as pain), and in improving the range of motion. However, it is important to note that steroidal injections only provide a temporary relief and prolonged episodes of such injections, may injure the joints in the long run

Surgical treatment measures include:

  • Cartilage grafting: Cartilage grafting is a surgical intervention technique that involves replacing lost cartilage within the knee joint, which may be damaged due to an arthritic disorder or a traumatic injury
  • Arthroscopic chondroplasty: Arthroscopic chondroplasty is a surgical intervention technique that involves repairing damaged cartilage within the knee; thus allowing the growth of healthy tissue in its place. This surgical procedure is performed using an orthopedic device, called an arthroscope, and is useful in treating mild to moderate rheumatoid arthritis
  • Partial knee replacement: Partial knee replacement is a procedure that involves the removal of a part of the knee joint. The arthritic part of the knee is removed and replaced by a prosthetic implant. This is recommended if the arthritis is limited to a certain area of the knee
  • Total knee arthroplasty: In total knee arthroplasty, the knee joint cartilage is completely removed. It is then replaced by a metal and plastic prosthetic implant. This surgical procedure is recommended, if the entire knee joint is acutely affected by the inflammatory and degenerative joint disorder

How can Arthritis of the Knee be Prevented?

Common recommendations to help prevent Arthritis of the Knee include:

  • Healthy body weight: Maintaining a healthy body weight can help reduce abnormal pressure within the joints, which may decrease the risk of arthritis
  • Healthy diet: Individuals who consume a healthy diet regularly, may decrease their chances of developing Knee Arthritis 
  • Use protective gear: Individuals who participate in high-risk sports activities (like football), should wear appropriate safety equipment to help prevent the possibility of injuring their knees, or other joints
  • Regular stretching exercise helps decrease the incidence of development of Arthritis of the Knee

What is the Prognosis of Arthritis of the Knee? (Outcomes/Resolutions)

  • The long term prognosis with arthritis depends on the specific type of inflammatory and degenerative disorder an individual develops, and the severity of the condition
  • If the cause of Knee Arthritis is detected early, and proper, aggressive treatment provided; then, the quality of life can be substantially improved. This also helps avoid any serious complications from arising in the knee joint
  • Degenerative Osteoarthritis of the Knee is a debilitating disorder. A high percentage of patients who develop this disorder may experience a gradual degeneration of their knee joint, during their lifetime

Additional and Relevant Useful Information for Arthritis of the Knee:

Fine needle aspiration (FNA) of joint fluid analysis procedure:

  • A needle is inserted within the joint space and the accumulated fluid aspirated with a syringe, which is then sent to a laboratory for analysis
  • The tests a laboratory may perform would include:  Analysis of the type of cells present in the fluid, chemical composition of the fluid, and examination of the fluid under the microscope, for the presence of crystals
  • If an infection is suspected as the cause for fluid accumulation at the joint, then a joint fluid culture may be performed, to remove fluid from the joint

One must be careful while adopting unproven and non-evidence based claims, such as copper bracelets and magnets, for treating joint disorders. Your healthcare provider is the best source for advice, on new methods of treatment.

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: July 9, 2013
Last updated: April 18, 2018