Synthesis of Evidence on the Combination of High-Intensity Laser Therapy and Rehabilitation Exercise for Knee Osteoarthritis: An Umbrella Review of Systematic Reviews

Abstract

High-intensity laser therapy (HILT) is a promising adjunctive treatment for knee osteoarthritis (KOA) due to its deep tissue penetration and anti-inflammatory effects. However, inconsistent findings hinder clinical interpretation. This umbrella review synthesised current evidence on the effects, safety, and clinical applicability of HILT in KOA management. A systematic search of five electronic databases was conducted in accordance with PRISMA guidelines, covering studies up to December 2024. Eligible systematic reviews included adult populations with KOA receiving HILT, assessing outcomes such as pain, stiffness, physical function, and safety. Methodological quality was evaluated using AMSTAR-2 and PRISMA checklists. The Corrected Covered Area (CCA) was calculated to assess overlap among primary studies. Seven systematic reviews published between 2017 and 2024 were included, comprising 50 unique primary studies involving adults aged 40–70 years. The CCA score of 0.047 indicated minor overlap. Most studies applied HILT in combination with rehabilitation exercise rather than as a standalone therapy. HILT significantly reduced pain and improved physical function, often exceeding minimal clinically important differences. Treatment parameters ranged from 808–1064 nm and 0.51–120 J/cm², administered over 4–8 weeks. Compared to low-level laser therapy, HILT demonstrated greater effects in pain relief and functional outcomes, with a favourable safety profile. While HILT can be used independently, combining it with exercise is the most commonly applied and effective approach for KOA. Despite promising results, variability in protocols and limited long-term data highlight the need for standardised treatment guidelines and further research.