Arthritis is a term that generally describes any condition where there is inflammation (and pain) of a joint.  This can be present at any joint, can present at various levels of severity, and can be caused by many different things.  The most common form of arthritis is osteoarthritis, also referred to by some as "wear and tear" arthritis.  It is the general breakdown of cartilage in a joint that occurs as we age. 

While it is true that arthritis cannot be reversed, there are treatments available that aim to slow the progression of joint degeneration and depending on the location, there are surgical treatment options to decrease pain from arthritis by replacement of joints or by fusing the joint.  Replacements of joints are available for hips, knees and finger joints.  In the foot, the joints across the ball of the foot have replacements available, and some physicians perform replacements of the ankle joint.  More conservative treatment includes custom orthotic inserts for the shoes.  This helps to hold the structure of the foot stable during gait (walking) and this decreases bone-on-bone grinding which is where pain typically stems from.  Spurring around a joint can occur with arthritis too, and if this is the primary source of pain, the spurs can be accommodated in different types of shoes or the spurs can be surgically removed.