Find information about common, infrequent and rare side effects of diclofenac oral This study compared the safety and effectiveness over a 26-week period of three weekly intra-articular injections of SYNVISC (hylan g-f 20) and of physiological saline in 29 subjects (29 knees) with osteoarthritis of the knee. The results of the study were similar to those in the German multicenter study, except that the significance levels in most comparisons were smaller (see Tables 3A and.