The human knee, a marvel of bone and joint development consisting of four major ligaments, and two menisci for both sides of the joint, along with muscle and tendons to protect it - even a bone is in the front to provide greater protection that the patella provides, in addition to strength. Arthritis of the knee is both debilitating and painful, leading to decreased pace in walking, inability to run, and in the most severe cases requiring a knee replacement to alleviate the pain and suffering involved with it. There are three major causes of arthritic knees and each one is different - but they all result in pain and inflammation.
Firstly, let's start with old reliable. Osteoarthritis is by far the most common form of arthritis out there today, and will most likely remain so for the entire lifespan of human beings. With more than half of all people over the age of sixty afflicted with osteoarthritis it is no surprise so many drugs are produced to alleviate pain. Osteoarthritis is a slow and progressive degeneration of the joint where the cartilage gradually wears away. Treatment options are to lose weight if the patient is overweight, change eating habits, use a mild pain reliever, or in the worst cases have a total knee replacement.
Secondly, we have the ever more virulent and painful disease caused by the body's own immune system - Rheumatoid Arthritis - in which the body attacks and destroys the joints cartilage, and usually afflicts both knees. There is no cure, and treatments involve dietary changes, exercise, preventative drugs, and in the end a knee replacement.
Thirdly, one of the most common for athletes and the overweight, Post-Traumatic arthritis. This form often occurs after an injury to the knee, such as a fracture, a ligament breaking, and a meniscus tear. Usually arthritic onset occurs a few to several years after the event that triggers it and slowly begins to act just as osteoarthritis does. Treatments include repair surgery, dietary changes, lifestyle changes, or total knee replacements. Although in both cases there is the option of cartilage grafting, total or partial knee arthroplasty and arthroscopic surgery to clean it of debris.