Intra-articular Hyaluronic Acid Injections May Be Beneficial in Patients with Less Advanced Knee Osteoarthritis: A Systematic Review of Randomised Controlled Trials

Knee osteoarthritis is a degenerative joint disease that impairs quality of life. Hyaluronic acid (HA) injections are used to restore synovial fluid viscosity and improve joint function.

The present systematic review investigated the prognostic factors influencing the effect of intra-articular HA injections for knee osteoarthritis (OA). The endpoint of interest was whether patient characteristics and molecular weight of the HA influence patient-reported outcome measures (PROMs) at different follow-ups.

This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses: the 2020 PRISMA statement. All randomised controlled trials (RCTs) investigating the efficacy of intra-articular HA injections in the knee were accessed. Data concerning the visual analogue scale (VAS), Western Ontario and McMaster Universities Arthritis Index (WOMAC) and Lequesne scales were collected at baseline and the last follow-up. OA was scored using the Kellgren–Lawrence (KL) classification. The endpoint of interest was whether patient characteristics and the molecular weight of HA influence clinical outcomes.

The study included 71 RCTs and data from 10,590 patients; 67% (7082 of 10,570) were women. The mean age of the patients was 61.8 ± 5.1 years, and the mean body mass index (BMI) was 27.8 ± 2.3 kg/m².

HA injections lead to an initial worsening of symptoms; however, patients with early stage osteoarthritis, particularly older women, may experience significant long-term improvements. Further research should standardise treatment protocols and investigate the role of HA molecular weight in optimising outcomes.