Primary osteoarthritis (OA) of peripheral joints is a common disease mainly occurring after the age of 50. It is important to distinguish primary from secondary OA. Younger age at disease onset, rapid progression, unusual disease manifestations and co-morbidities are signs of secondary OA. This review outlines an important group of secondary OA. Hereditary metabolic diseases can exhibit joint involvement. For some of these diseases, correct diagnosis is critical, since appropriate therapy influences not only joint function and quality of life, but can also prevent relevant end-organ damage.