Inside a healthy joint, moving surfaces are covered by a layer of cartilage which stops two bone surfaces rubbing together and creating friction. Movement of the joint is made smoother still by the synovial fluid, which bathes the cartilage in lubricating molecules.
With osteoarthritis, the integrity of the joint is compromised.
The cartilage begins to wear thin, sometimes getting worn away completely, while the level of lubricating molecules in the synovial fluid and on the cartilage become depleted.
The degradation inside osteoarthritic joints contributes to inflammation, joint stiffness and pain upon movement. As the disease progresses, symptoms become more severe and debilitating, with pain sometimes becoming a permanent feature.