Patients are eligible if they suffered from persistent active KJS (characterized by pain, tenderness, and effusion), which had proved resistant to surgical treatment or to repeated IA corticosteroid therapy, or unresponsive to a minimum of 6 months second-line drug therapy with DMARD-, and/or anti-TNFα biologic agent monotherapy and systemic oral corticosteroid treatment, or to a combination therapy (drug failure is defined as discontinuation because of intolerable adverse effects or lack of clinical efficacy).