Osteoarthritis (OA) is an amazing response of your body. Osteoarthritis as defined by the Arthritis Society as the most prevalent kind of arthritis, affecting more than three million Canadians. It occurs when cartilage (the tough elastic material that covers and protects the ends of bones) begins to wear away. Cartilage is an essential part of the joint - not only does it act as a shock absorber, it also enables the joint to move smoothly. With OA, the cartilage erodes, eventually resulting in pain, stiffness, swelling and bone-on-bone movement in the affected joint.
Lets look at the key point above, cartilage wearing out. One can assume that if you can protect and care for the cartilage in any joint, be it the knee or the spine, than you can delay the development of OA. So to explain why cartilage wears out lets imagine a carpet or rug in a home. If you care for the rug, use spill-guard protector, spot treatments on spills, regularly shift the furniture on the carpet to evenly distribute traffic and take care of small tears or fraying before they become a larger tear you can greatly prolong the life of a rug. If you focus the traffic over a small area, never shift furniture, let small rips and damage accumulate and ignore small spills until they sink in, the rug will not last very long.
Now lets look at a joint. If you maintain full mobility, strength of the muscles surrounding the joint, while properly managing small bumps or injuries you can allow the body to properly respond when a problem arises. The issue of OA develops when the joint is not allowed proper motion due to muscular or joint restriction/subluxation. Over time there will be abnormal forces rubbing, pulling and pressing on the cartilage. Cartilage within a human body is designed for very specific forces when these forces change the cartilage is unable to adapt. Think about a house that was built to withstand the forces of gravity (i.e not fall directly down into the ground). When an earthquake occurs, the house is likely unable to adapt to these different forces. If that earthquake were to happen over and over, the likelihood of the house standing decreases.