How does secondary Osteoarthritis differ from the primary?
Secondary OA has the same clinical features as primary OA except that it has an identifiable etiologic factor and may have a different joint distribution. Atypical joint involvement (MCP joints, wrists, elbows, shoulders, ankles, and MTP joints) or early age onset of OA should prompt a search for an underlying disease process. A classic example is OA seen in the MCP joints of the hands in association with hemochromatosis (young patients) and CPP arthritis (older patients).
