Hyaluronic acid in knee osteoarthritis: preliminary results using a four months administration schedule.

AIM: To evaluate the therapeutic trajectory of intra-articular injections of hyaluronic acid at high concentration (2%) performed at 4-month intervals. METHODS: Subjects with knee osteoarthritis received, after a weekly injection of 32 mg/2 mL hyaluronic acid for 3 weeks, a single injection of 50 mg/2.5 mL hyaluronic acid (not cross-linked, molecular weight 800-1200 kDa) at 4-month interval (4, 8 and 12 months). Clinical assessment (visual analogic scale [VAS] for pain at rest and during activities, Lequesne Index [LI], Knee Injury and Osteoarthritis Outcome Score (KOOS), and monthly non-steroidal anti-inflammatory drug consumption) was performed at baseline, and after 1, 4, 6, 8, 12 and 14 months. RESULTS: In the 15 knees treated, pain decreased (baseline vs. 14 months: VAS at rest, 3.7 ± 1.7 vs. 1 ± 0.7 [P < 0.000]; VAS activities, 6.2 ± 1.7 vs. 2.6 ± 1.3 [P < 0.000]) and function improved (baseline vs. 14 months: KOOS, 51.9 ± 15.3 vs. 70.2 ± 13.7 [P < 0.000]; LI, 10 ± 3.8 vs. 5.4 ± 2.4 [P < 0.000]) significantly. CONCLUSIONS: This schedule provides persistent positive results in terms of reduced pain and improved function, optimizing the protective properties of the hyaluronic acid used.