Objective: To compare the two hyaluronan preparations with different molecular weights and a methyl prednisolone acetate preparation in terms of efficacy and adverse effects in knee osteoarthritis.

Materials and Methods: A total of 75 patients diagnosed with knee osteoarthritis according to the American College of Rheumatology (ACR) criteria were enrolled in this study. Sixty-nine patients completed the study. The patients were randomized into three groups: Group I (n=22) received 6-methylprednisolone acetate (6-MPA), Group II (n=24) low molecular weights hyaluronic acid (LMW HA), and Group III (n=23) received high molecular weight hyaluronic acid (HMW HA). All the three groups had three intraarticular injections at one-week intervals. The study was conducted with a prospective and single-blinded fashion. The patients were assessed in terms of radiological stage, functional stage, patient and physician satisfaction parameters, daily acetaminophen intake, physician’s and patient’s global assessment, pain, as well as SF-36, Lequesne’s algofunctional index and Womac osteoarthritis index scores. Assessments were done at pretreatment, posttreatment, and at three and six months posttreatment. Presence of effusion and local and systemic adverse events were recorded.

Results: There were no differences among groups at baseline except for the functional stage. Intra-group comparisons demonstrated significant improvements within six months of treatment in some of the subsections of SF-36, except for radiological stage and functional stage, as well as in other parameters. In inter-group comparisons, significant differences were noted in patient’s and physician’s global assessment of osteoarthritis at second month and in post-treatment SF-36 Social Functioning compared to pre-treatment (p<0.05) (p<0.05). No serious systemic adverse effects were noted except for transient local adverse effects.

Conclusion: As a result, with this first study comparing two hyaluronic acid preparations with different molecular weights and methylprednisolone acetate, significant improvements extending up to 24 weeks in all the three groups in all variables were determined except for some parts of SF-36. As for the comparisons between the groups, only at the second month, Group I (6-MPA) and II (LMW HA) were significantly superior to Group III (LMW HA) in terms of patient’s and physician‘s global assessment of osteoarthritis and, after the treatment, in SF-36 Social Functioning scores. No significant differences were observed in other parameters.