What is osteoarthritis?
Osteoarthritis is the most common cause of decreased function in the elderly, but occurs even in young and middle-aged people. Osteoarthritis is a disease that affects cartilage, ligaments, joint capsules, joint fluids and bone. A key feature is the loss of the articular cartilage which can be identified by x-ray. There are important consequences for the patient in the form of pain and decreased function. However not all joints that have osteoarthitic changes are painful. Approximately 5% of the population between 35 and 54 years of age has radiographic evidence of osteoarthritis, but this increases to 15-20 % over the age of 45 years. About one sixth of adults have knee pain that has lasted for more than three months [1, 2]. Even if symptomatic osteoarthritis isn’t as common as radiological changes, it is estimated that about 10% of men and 18% of women aged over 60 years have discomfort related to osteoarthritis [3].
The etiology is not entirely known, but several risk factors have been defined: age, overweight, gender, heredity, previous joint injury, occupations that put excess load on joints, athletics performed at the professional level and muscle weakness [4-10].
Osteoarthritis is characterized by an imbalance between the production and the breakdown of cartilage, which leads to failing function of the joint. The concept of the “worn out” joint, which previously used as a synonym for osteoarthritis, is misleading and can make one think of osteoarthritis as an incurable condition, that should be protected from further joint load. This is unfortunate since cartilage is dependant on moderate amounts of dynamic load to maintain the balance between production and breakdown. Recent findings indicate that osteoarthritis is not caused by wear and tear [11], and that moderate physical activity does not increase the risk of osteoarthritis [12].
Osteoarthritis is most often diagnosed using radiographic examination. However, radiographic changes develop slowly and most people with pain in hip or knee have no radiographic signs of osteoarthritis [13]. This lack of correlation between symptoms and radiographic examination at early stages of the disease might delay the diagnosis and treatment, and also cause anxiety to the patient.
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