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Tidal Irrigation Outlasts Steroids in One OAStudy

C H I C A G O — Tidal irrigation leads to more sustained benefits than intraarticular corticosteroid injections in patients with knee osteoarthritis, particularly in those without an effusion, Nigel K. Arden, M.D., said at the 2004 World Congress on Osteoarthritis. Both treatments significantly improved pain and function at 2 weeks, according to results from a randomized, single-blinded, parallel group trial involving patients with symptomatic knee OA. But the benefits were maintained only in the irrigation group at 26 weeks. Tidal irrigation, which involves infusing saline into the knee under local anesthesia to repeatedly distend the capsule, is thought to provide benefit by disrupting intraarticular adhesions and by cleansing away debris and inflammatory cytokines, said Dr. Arden of Southampton (England) University Hospitals NHS Trust. The 150 study participants were randomized to intraarticular corticosteroid injections with 40 mg triamcinolone and 2 mL of 1% lidocaine or irrigation of the knee with 500-1,000 mL of normal saline. At 2 weeks, pain scores had improved significantly from baseline, and there were no significant differences between treatment groups. The mean pain score for both groups was 243 at baseline, on a 0-500 scale. At 2 weeks scores fell to 168 in the steroid group and 155 in the irrigation group. At 26 weeks, significant pain relief was maintained only in the irrigation group (mean 173 vs. 232 for the steroid group). A similar pattern was seen for function at 26 weeks. At baseline, 61% of patients had an effusion, and at 2 weeks’ follow-up, there was little difference between treatment groups in this subset of patients. By 26 weeks, however, only patients treated with tidal irrigation had significant improvement, and this was more marked in patients without an effusion. Among patients without an effusion, the mean pain score for those treated with irrigation was 164 vs. 262 for patients treated with injections. Among patients with an effusion, the mean pain score for those treated with irrigation was 180 vs. 214 for patients treated with injections. Patients’ overall assessment of treatment was similar at 2 weeks’ and 4 weeks’ follow-up. But patients’ self-assessments significantly favored tidal irrigation at 12 and 24 weeks, Dr. Arden said at the meeting, sponsored by the Osteoarthritis Research Society International. Such findings in no way account for the placebo effect of the interventions, John D. Bradley, M.D., told this newspaper. Generally, “the more elaborate the intervention, the more potent the placebo effect.” In their investigation, Dr. Bradley and colleagues at Indiana University, Indianapolis, tracked 180 randomized subjects with knee OA for up to 12 months following randomization to tidal irrigation or a sham procedure, which involved placement of a needle through the soft tissue and down to, but not through, the joint capsule. Both groups received intraarticular anesthesia with bupivacaine. The investigators concluded that after adjusting for baseline differences between groups, there were no differences between outcomes from the real and the sham procedures (Arthritis Rheum. 2002; 46:100-8). Dr. Bradley noted that psychological factors and the subjects’ guesses regarding the identity of their treatment correlated with their response to treatment. ■ The controversial procedure is thought to disrupt intraarticular adhesions, and clear away debris and inflammatory cytokines. C O U R T E S Y D R . N IG E L K . A R D E N