Viscosupplementation for knee osteoarthritis: current evidence and recommendations.

Osteoarthritis (OA) is the most common joint disorder worldwide and is a leading cause of pain and disability. Appropriate management of younger patients with milder disease remains a challenging area of intense research. Viscosupplementation attempts to restore the biomechanical and biochemical functions of normal synovial fluid hyaluronic acid. Several preparations with varying characteristics are currently available. The literature suggests a small benefit and relative safety, but several recent large meta-analyses have reported conflicting results. Major clinical guidelines provide inconclusive recommendations. Viscosupplementation may be a viable option in younger patients with milder OA where other non-operative modalities are also only modestly successful, but further investigation is clearly warranted. Limitations due to study heterogeneity, outcome reporting, and bias can each be addressed with improved research methodology.