Arthritisrefers to a group of diseases that cause inflammation and swelling of one or more joints. It can affect any joint of the body, but is especially common in the knees, which are large weight-bearing joints subject to increased loading and repetitive wear and tear.
The type of arthritis that results from wear and tear over time or overuse of joints isosteoarthritis, which is also called degenerative joint disease and affects more than 30 million Americans. In osteoarthritis of the knee, bones rub directly against bone when cartilage, a connective tissue that provides cushioning and shock absorption within joints, wears away.
Other common forms of arthritis that affect the knees arerheumatoid arthritisandpsoriatic arthritis, which are autoimmune conditions that cause widespread joint inflammation and other systemic symptoms throughout the body.
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Knee Symptoms
Symptoms ofknee arthritiscan be intermittent or chronic and progressive in nature, getting worse over time. Knee arthritis can vary in intensity, from mild or moderate symptoms to severe disability that makes everyday tasks and functional movements like standing, walking, squatting, andgoing up and down stairsvery difficult and painful.
Common symptoms of knee arthritis include:
Causes of Knee Pain and Treatment Options
Systemic Symptoms
Rheumatoid Arthritis
Rheumatoid arthritis (RA) is an autoimmune condition where the immune system attacks the joints, causing pain, inflammation, and swelling. Over time, cartilage within joints breaks down, narrowing the space between bones, and joints can become unstable or stiff. If left untreated, rheumatoid arthritis can cause permanent and irreversible joint damage.
Unlike osteoarthritis, which is more likely to develop on one side of the body, rheumatoid arthritis is usually symmetrical, affecting both sides of the body, and commonly affects the knees. RA is also more likely to affect multiple joints of the body, causing pain, stiffness, swelling, inflammation, warmth, and redness, and can also cause systemic symptoms like fatigue, fever, and weakness. Women are two to three times more likely to be diagnosed with RA than men.
Other systemic symptoms RA may cause include:
Rheumatoid Arthritis: Tests to Diagnose and Monitor RA
Psoriatic Arthritis
Alternatively, about 30% of patients withpsoriasis, an inflammatory condition of the skin, develop an autoimmune, inflammatory form of arthritis called psoriatic arthritis.Psoriatic arthritis can affect the joints of the entire body and result in permanent joint damage if left untreated. Psoriasis affects 7.4 million adults in the United States.
Systemic symptoms of psoriatic arthritis include:
What Is Psoriatic Arthritis of the Knee?
When to See a Doctor
If you have been experiencing significant knee pain, stiffness, decreased mobility, or swelling for more than three months that is interfering with your ability to perform everyday tasks, making it uncomfortable to sit, stand, or walk, you should schedule an appointment with a doctor to address your symptoms. Symptoms of arthritis can worsen over time if left untreated.
A Word From Verywell
3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Mease PJ, Gladman DD, Papp KA, Khraishi MM, Thaçi D, Behrens F, Northington R, Fuiman J, Bananis E, Boggs R, Alvarez D.Prevalence of rheumatologist-diagnosed psoriatic arthritis in patients with psoriasis in European/North American dermatology clinics.J Am Acad Dermatol. 2013;69(5):729-735. doi:10.1016/j.jaad.2013.07.023
Rachakonda TD, Schupp CW, Armstrong AW.Psoriasis prevalence among adults in the United States.J Am Acad Dermatol. 2014;70(3):512-6. doi:10.1016/j.jaad.2013.11.013
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