Synovial fluid hydroxyproline fractions before and after osmic acid treatment in rheumatoid arthritis

Synovial fluid total, dialysable and non-dialysable hydroxyproline were determined in patients with Rheumatoid Arthritis before intra-articular osmic acid injection and on days 2 and 4 after this local treatment. On day 2 the increase in dialysable hydroxyproline paralleled the increase in non-dialysable hydroxyproline. Patients with the highest pre-treatment dialysable hydroxyproline levels also had the highest levels of this fraction on day 2 suggesting that articular damage proceeds after osmic acid injection. However, on day 4 dialysable hydroxyproline levels were consistently lower than before the treatment; the same pattern was observed with non-dialysable hydroxyproline, except for all the joints but one, where effusion recurred 6-12 months after osmic acid treatment. This study suggests that the determination of synovial fluid non-dialysable levels 4 days after osmic acid injection may provide a clue to the prediction of recurrent joint effusion and possibly justify a complementary injection either with osmic acid or with a beta-emitting isotope.