Abstract: The present disclosure is directed to methods and compositions for treating osteoarthritis and preventing osteoarthritis, by administering a compound that modulates one or more components in the complement system. In one embodiment, a compound that inhibits a component in the complement system is administered to prevent, delay the progression of, or treat osteoarthritis. In other embodiments, compounds with specific inhibition of a component in a particular pathway in the complement system, such as the alternative, mannose binding lectin, and/or classical pathway, are administered to a subject having osteoarthritis or at risk of developing osteoarthritis.