Knee problems can be the result of disease or injury.
A number of diseases can affect the knee. The most common is arthritis. Although arthritis technically means "joint inflammation," the term is used loosely to describe many different diseases that can affect the joints. Some of the most common forms of arthritis and their effects on the knees are described a bit later in this publication.
Knee injuries can occur as the result of a direct blow or sudden movements that strain the knee beyond its normal range of motion.
Sometimes knees are injured slowly over time. Problems with the hips or feet, for example, can cause you to walk awkwardly, which throw off the alignment of the knees and leads to damage.
Knee problems can also be the result of a lifetime of normal wear and tear. Much like the treads on a tire, the joint simply wears out over time...Read more about knee problems NIH - National Institute of Arthritis and Musculoskeletal and Skin Diseases
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