Efficacy of Three Weekly Injections of a Bacterial-- Sourced Hyaluronate on Pain and Function in Patients With Knee Osteoarthritis (OA)

Background: Viscosupplementation with intra-articular hyaluronate injections is a safe and effective treatment of knee osteoarthritis. There are several forms of hyaluronate with different origin, method of production, molecular weight, dosing instructions and possibly clinical outcomes. Most current hyaluronate products are avian in origin, and only few are bioengineered via bacterial fermentation. The purpose of this study was to evaluate the efficacy and safety of 3 weekly injections of a bacterial-sourced hyaluronate (Hya-Joint) in patients with knee osteoarthritis.

Methods: As a prospective randomized observer-blind study done in a university-affiliated tertiary care medical center, patients with knee osteoarthritis for at least 6 months were enrolled. Eligible patients were randomized to receive three weekly intraarticular injections of either bacterial-sourced hyaluronate (Hya-Joint) or avian-derived hyaluronate (Hyalgan) into the target knee. The primary outcome was the visual analog scale (VAS) change from baseline for knee pain at 6-month follow-up. Secondary outcome measures included Lequesne index, timed up and go test (TUG), patients' global satisfaction and analgesics consumption.

Results: A total of 95 participants were randomly assigned and 89 participants completed the study. Both groups had significant improvements in pain as early as 1 and 2 weeks after the first injection, and the pain-reduction effects could last for 6 months, with no between-group differences. The Lequesne index scores and results of TUG tests improved significantly from baseline in both group at all follow-up visits (p<0.001 for each test compared with baseline), with no significant between-group differences at 1-month and 6-month follow-up. However, significantly greater improvements favoring the Hya-Joint group were noted at 3-month follow-up (p<0.05). No between-group differences were seen regarding the use of analgesics. Both groups reported high satisfaction at 6-month follow-up. No serious adverse events occurred.

Conclusions: Three weekly injections of hyaluronate (Hya-Joint) are safe and well tolerated, provide rapid pain relief as early as 1 and 2 weeks after the first injection, and improve function in patients with knee osteoarthritis. The treatment effects can last for 6 months.

Inclusion criteria

• (1) age 40 years or older, presence of a primary knee OA with knee pain for at least 6 months despite conservative treatment (rest, physical therapy, orthoses or pain medications etc.); (2) had average pain on knee movement of at least 3 cm on a 10-cm VAS; (3) had a current Lequesne index score (described below) >7 (possible range, 0-24); (4) were willing to discontinue all nonsteroidal anti-inflammatory drugs (NSAIDs) or other analgesic medication (except for rescue medication) for the duration of the study; and (5) were willing to not receive physical therapy or trial of shoe modifications or orthoses during the study period.

Exclusion criteria

Exclusion criteria included previous orthopedic surgery on the spine or lower limbs, knee instability or marked deformity on examination, clinically apparent tense effusion of the knee, intra-articular steroid or HA injection in any joint within the past 6 months, and concomitant inflammatory arthropathy or other rheumatologic, neurological, cardiovascular or psychiatric disorders that would interfere with the clinical assessment during the study period.

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