Erratum to: Mod Rheumatol DOI 10.1007/s10165-012-0668-z

The correct affiliation of Taisuke Nitobe is Department of Orthopedics, Seihoku Chuoh Hospital, 41 Nunoyacho, Goshogawara, Aomori 037-0053, Japan. The authors apologize for any inconvenience this error may have caused.