Short-term outcome of painful bone marrow oedema of the knee following oral treatment with iloprost or tramadol: results of an exploratory phase II study of 41 patients

Objectives. To compare the therapeutic effects of oral iloprost and tramadol on the outcome of bone marrow oedema (BME) of the knee by MR imaging and clinical assessment. Methods. Forty-one patients with painful ischemic or mechanical BME of the knee were enrolled in a double-blind, randomized controlled study. Patients were randomized either to iloprost (n=21, group 1) or tramadol (n=20, group 2). The treatment duration was 4 weeks. The Larson knee score was used to assess function before treatment and then 3 days, 1, 2, 3, 4 weeks and 3 months after the start of treatment. Short tau inversion recovery and T1-weighted MR images of the affected knees were obtained before and 3 months after the start of treatment. Bone marrow oedema was assessed visually and by computer-assisted quantification for baseline and follow-up MR examinations. Results. Thirty-three patients completed the study as scheduled. The mean Larson score improved from 58.6 points to 81.8 points in group 1, and from 59.6 points to 86.8 points in group 2, after 3 months (no significant difference between the treatment groups). On MR images, complete BME regression in at least one bone was observed in nine patients (52.9%) in group 1, as opposed to three patients (18.7%) in group 2, after 3 months (P= 0.034). Correspondingly, the median BME volume decreased by 58.0% in group 1, and by 47.5% in group 2. Conclusions. The analgesic effect of iloprost and tramadol was similar. BME regression on MR images was more pronounced under iloprost treatment.