With advancing age plus wear and tear, cartilage tends to soften, deteriorate and develop cracks and holes. That's what osteoarthritis is all about. Cartilage that has been damaged by previous injuries may be vulnerable to osteoarthritis so it's important to get proper treatment for even minor injuries. Excess weight and genetics may also be factors.
That's why it's key to be in shape. So, you guys think it's safe to assume that all morbidly overweight people have some form of arthritis?