• Thompson articular index [ Time Frame: 2 weeks ] [ Designated as safety issue: No ]
  

• Knee Joint Articular Index [ Time Frame: 2 weeks ] [ Designated as safety issue: No ]
  

Drug: etanercept
etanercept 12.5mg, intraarticular injection administered once every two weeks for an eight week period
Drug: placebo
Placebo (NaCl) 0.5 ml intraarticular injection

The study is a single centre, placebo-controlled, single-blind, cross-over trial, with randomization of treatment sequence and open-label extension to be conducted in rheumatoid arthritis, psoriatic arthritis and spondyloarthropathies patients with resistant knee joint synovitis (KJS). 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).

Concomitant Treatments: stable, appropriate doses of DMARDs (methotrexate, sulfasalazine, hydroxychloroquine, cyclosporine), DMARD combinations or low dose oral corticosteroids (≤10 mg prednisone) with or without non-steroid anti-inflammatory agents will be continued throughout the study. Patients will be permitted stable doses (no greater than the maximum dose recommended by the manufacturer) of non-steroidal anti-inflammatory drugs (NSAIDs) but will be permitted to use only one NSAID at any given time. No analgesic could be taken before undergoing assessment on the day clinical evaluations will be performed. Treatment: Each dose of study drug will be administered as one intraarticular (IA)injection carried out in each single knee joint that will be randomly assigned to blind treatment with 0.5 ml of etanercept (E) (12.5mg) or placebo (P) (NaCl). The IA injection will be administered once every two weeks for an eight week period. After 2 weeks time the patients will be crossed-over and each arthritic knee joint will receive E (12.5 mg) for four times or P for three times, respectively, administered every two weeks for an eight week period. All the IA injections will be administered after synovial fluid aspiration by the same operator. The study, patients with KJS flare up after IA injection will be asked to enter the open-label IA extension treatment with IA-E injection once every two weeks, for eight weeks. Safety assessment: routine chemistry, haematology and urinalysis assessments will be performed at the screening, baseline and final examinations. Tuberculosis screening will be performed at the onset of the study. Patients will be evaluated clinically for adverse events at each examination. Local tolerance at the injection site(s) will be evaluated at all the controls. Assessment of the patients' response: will be performed at baseline (T0) and at 2 (T2), 4 (T4), 6 (T6), and 8 (T8) weeks, and at the end of the 10 week single-blind, cross-over study or at the end of the open-label IA extension-study (up to 14 weeks) (Tend). The primary efficacy endpoint is the Thompson articular index (THOMP) sum of scores for each knee joint, of pain on movement (0-3), soft tissue swelling (0-3) and warmth (0-3); (range 0-9). Secondary endpoints are: the Knee joint articular index (KJAI): the sum of the tenderness scores (0-3), joint swelling (0-3), the ballottement of patella or the "bulge sign" (0-2), and range of knee joint flexion (0-3) and extension (0-3) (KJAI, range 0-14). Standard joint evaluation comprise: the 66/68 swollen joint number (SJN) and tender joint number (TJN) (0-1); a modified Ritchie articular index (RAI), by assessment of 30 joints for tenderness (0-3) (range: 0-90), (including hand and foot distal interphalangeal joints (DIP) of each side as a group; the pain visual analogue scale (VAS) (0-100mm), the health assessment questionnaire (HAQ)- disability index (0-3) and the SF36 (range 0-24) at the above time points. The serum CRP, the ESR, and the maximal synovial thickness (measured by grey-scale ultrasonography and contrast-enhanced magnetic resonance imaging) will be assessed at baseline and at the end of the treatment.