Although both corticosteroid and hyaluronic acid injections are widely used to palliate the symptoms of knee osteoarthritis, little research involving a comparison of the two interventions has been done. We tested the hypothesis that there are no significant differences between Hylan G-F 20 (Synvisc) and the corticosteroid betamethasone sodium phosphate-betamethasone acetate (Celestone Soluspan) in terms of pain relief or improvement in function, as determined by validated scoring instruments.
One hundred patients with knee osteoarthritis were randomized to receive intra-articular injection of either Hylan G-F 20 or the corticosteroid, and they were followed for six months. The patients treated with Hylan G-F 20 received one course of three weekly injections. The patients treated with the corticosteroid received one injection at the time of enrollment in the study, and they could request one more injection any time during the study. An independent, blinded evaluator assessed the patients with the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), a modification of the Knee Society rating system, and the visual analog pain scale.
Both the group treated with the corticosteroid and the group treated with Hylan G-F 20 demonstrated improvements from baseline WOMAC scores (a median decrease from 55 to 40 points and from 54 to 44 points, respectively; p < 0.01 for both). The scores according to the Knee Society system did not significantly improve for the patients who received the corticosteroid (median, 58 to 70 points; p = 0.06) or for those who received Hylan G-F 20 (median, 58 to 68 points; p = 0.15). The scores on the visual analog scale improved for patients receiving Hylan G-F 20 (median, 70 to 52 mm; p < 0.01) but not for the patients who received the corticosteroid (median, 64 to 52 mm; p = 0.28). However, no significant differences between the two treatment groups were found with respect to the WOMAC, Knee Society system, or visual analog scale results. Women demonstrated a significant improvement in only one of the six possible outcome-treatment combinations (the WOMAC scale), whereas men demonstrated significant improvements in five of the six outcomes (all measures except the Knee Society rating system).
No differences were detected between patients treated with intra-articular injections of Hylan G-F 20 and those treated with the corticosteroid with respect to pain relief or function at six months of follow-up. Women demonstrated significantly less response to treatment than men did for both treatments on all three outcome scales. Such significant gender-related differences warrant further investigation.