Objective: To evaluate, in a pilot, open clinical trial on 40 patients with knee osteoarthritis, the structural changes in the synovial membrane and cartilage following treatment with intra-articular hyaluronic acid (HA-Hyalgan).
Methods: The structural effects of HA given as 5 weekly injections (20 mg/2 ml once a week for 5 weeks), were evaluated by microarthroscopy and morphological analysis of biopsy samples taken at baseline and after 6 months, under blind conditions. Clinical efficacy was also evaluated using visual analogue scales for pain and functional parameters.
Results: At 6 months, the microarthroscopic evaluation indicated that the majority of the patients (60%) showed no changes compared to baseline, while 32.5% of the patients showed improvement in the grading and/or extension of cartilage lesions and 7.5% showed a worsened condition. These changes were accompanied by a statistically significant reduction in the synovial inflammation (p = 0.001). The results were confirmed by morphological examination of the cartilage and synovial membrane. At 6 months compared to baseline, a statistically significant reconstitution of the superficial amorphous layer of the cartilage (p = 0.0039), an improvement in the chondrocyte density (p = 0.0023) and vitality (p = 0.05), and a statistically significant reduction in synovial inflammation (p = 0.0001) accompanied by a significant increase in the synovial repair process (p = 0.0001) were observed. Significant and long lasting improvement in pain and joint mobility were also seen after HA treatment. Joint effusion, when present, was reduced. The treatment was well tolerated.
Conclusion: Hyalgan represents a useful therapy for knee OA, with long-lasting symptomatic efficacy and potential positive effects on joint tissues. Other studies, in particular placebo-controlled studies, are warranted to confirm these promising results observed on joint tissues.