Hand osteoarthritis and generalized osteoarthritis: a need for clarification.

A proportion of patients with osteoarthritis (OA) have polyarticular involvement and are categorized as having generalized OA (GOA). However, a widely accepted definition of GOA does not exist. The topography of affected joints as well as the threshold number of affected joints used in defining GOA remain unidentified. According to number, site and clustering of affected joints, various subtypes of GOA, possibly related to different genetic factors, may exist. Such subtypes have still to be clearly identified. Among them, the association of hand and knee OA emerges as a probable subtype. Polyarticular involvement of hand joints is common, but may include various subtypes of differing significance. Further studies are needed to clarify the definition of GOA.