Viscosupplementation has been widely used for the treatment of knee osteoarthritis (OA). There is no well controlled trial comparing one injection regimen of HA for the treatment of knee OA. The purpose of this study was to compare the efficacy and safety of one intraarticular injection of a novel crosslinked HA (HYAJOINT Plus) with Synvisc-One for the treatment of knee OA.

In a prospective, randomized controlled, double-blind trial with 6-month follow up, patients with knee OA (Kellgren-Lawrence grade 2 or 3) were randomized to receive one intraarticular injection of 3 ml HYAJOINT Plus (microbial fermented HA, 20 mg/ml) (N=66) or 6 ml Synvisc-One (avian derived HA, 8 mg/ml) (N=66). The primary outcome was change in the visual analog scale (VAS) pain (0-100mm) over 6 months. Secondary outcomes included The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Lequesne index, Timed Up-and-Go test (TUG), single leg stance test (SLS), use of rescue analgesics and patient satisfaction.

Inclusion Criteria:

• symptomatic knee OA with pain for at least 6 months, despite conservative treatment such as analgesics, NSAIDs and/or physical therapy

• average pain on knee movement of 30 mm or greater on a 100-mm VAS

  • grade 2 or 3 knee OA according to the Kellgren-Lawrence grading system based on radiographs taken within the previous 6 months
  • Radiological evidence of bilateral knee OA was accepted if global pain VAS in the contralateral knee was less than 30 mm.

Exclusion Criteria:

• previous orthopedic surgery on the spine or lower limbs
• disabling OA of either hip or foot
• knee instability, clinical apparent joint effusion or marked valgus/varus deformity
• known allergy to avian proteins or HA products
• women ascertained or suspected pregnancy or lactating
• intraarticular injections within the past 6 months
• infections or skin diseases around the target knee
• any specific medical conditions (rheumatoid arthritis, hemiparesis, neoplasm, etc.) that would interfere with the assessments