Arthritis comes is several forms,including osteoarthritis, rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, etc. In osteoarthritis, the degeneration of the joint is not simply wear and tear, as doctors already know, but a change in the cartilage cells themselves. They don’t know what causes the cells to change in the first place. But you would have to say that if capillary density was not sufficient (and cartilage already has a tendency for low capillary density), the change to the cells would be inevitable. Rheumatoid arthritis is classified as an autoimmune disorder that often affects not only affects the joints, but the blood vessels and lungs as well. Again, the cart is before the horse. Arthritis doesn’t cause blood vessel damage, the modern diet and lack of exercise cause blood vessel damage, which in turn leads to arthritis.