Arthroscopic evaluation of potential structure modifying activity of hyaluronan (Hyalgan(R)) in osteoarthritis of the knee

Objective: Several reported studies suggest that repeated intra-articular injections of hyaluronan result in sustained relief from pain and functional disability in patients with knee osteoarthritis. Several in vivo data suggest that hyaluronan might have a beneficial structural effect in osteoarthritis. The objective of the study was to evaluate the potential structure-modifying effects of Hyalgan (500-730 kDa molecular weight), a highly-purified sodium hyaluronate. Design: Patients with painful knee osteoarthritis (ACR criteria) were enrolled in a prospective, controlled study of 1-year duration. After randomization, either conventional therapy or three cycles (every 3 months) of three intra-articular injections of Hyalgan (once a week during 2 weeks) were given. Clinical outcome was added using pain visual analog score (VAS), functional impairment: Lequesne's index, quality of life: arthritis impact measurement scale (AIMS?) and structural outcome using X-rays: joint space narrowing and arthroscopy: global assessment using VAS, SFA scoring and grading systems. Results: Of the 39 recruited patients, 36 completed the 1-year trial (19 in the Hyalgan group and 17 in the control group). There was no difference between groups at entry. Between-group comparison for changes in clinical parameters reached statistical significance for the quality of life index (AIMS(2): -0.4 +/- 0.7 vs +0.2 +/- 0.9 in the Hyalgan and control groups respectively, P < 0.05). Deterioration in the structural parameters was less in the Hyalgan group, with a statistically significant difference for two of the three evaluated parameters (overall assessment of chondropathy: +5.1 +/- 12.7 vs 16.7 +/- 18.3, P = 0.016; SFA scoring system: +3.7 +/- 7.3 vs +9.0 +/- 11.5, P = 0.05) in the Hyalgan and control groups, respectively. Conclusions: This study supports existing data concerning the favorable symptomatic effect of intra-articular injections of Hyalgan in osteoarthritis of the knee and suggests that repeated intra-articular injections of Hyalgan might delay the structural progression of the disease. Other studies are required to confirm these results and to determine the long-term monitoring of osteoarthritic patients using such local therapy.