Comparison of the efficacy of lower and higher molecular weight viscosupplementation in the treatment of hip osteoarthritis

We aimed to compare the efficacy of intra-articular injections of a lower molecular weight hyaluronan (LMW HA) (Ostenil) with a higher molecular weight viscosupplement (hylan G-F 20, Synvisc) in hip osteoarthritis. For this purpose, 43 patients (56 hips) with hip osteoarthritis with a visual analogue scale (VAS) pain score higher than 50/100, a Lequesne index greater than 6, and persistence of the pain for longer than 3 months despite all conservative methods were enrolled in the study and randomly assigned to two groups: 25 (32 hips) received LMW HA and the remaining 18 patients (24 hips) received hylan G-F 20. Three injections were administered once weekly to each patient under fluoroscopic guidance. During the 6-month follow-up period, the primary outcomes were assessed at the 1st, 3rd, and 6th month by VAS, WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index), and Lequesne index. The intra-articular injections produced a significant reduction in VAS, WOMAC, and Lequesne index scores in both groups. After three injections, improvement was prominent at the 1st month and maintained for 6 months in both groups. The percentage reduction was 38 and 40% (p<0.001) in VAS pain score, 43 and 40% in WOMAC (p<0.001), and 47 and 49% in Lequesne index (p<0.001) in the LMW HA and hylan G-F groups at the 6th month, respectively. However, there were no significant differences in outcomes between any of the measurements at the 1st, 3rd, and 6th month between the two groups (p>0.05). No systemic adverse effect was recorded. Local adverse effects consisting of pain and/or swelling were noted in 3 of 32 hips (9%) injected with LMW HA and in 3 of 24 hips (12.5%) injected with hylan G-F 20. In conclusion, both types of viscosupplementation produced a significant clinical improvement during the 6-month follow-up period. However, no significant difference was found in outcomes between higher and lower molecular weight hyaluronan.