Combined effect of therapeutic ultrasound and exercise on pain and swelling in people with knee osteoarthritis: a systematic review

Background Knee osteoarthritis (KOA) is a chronic musculoskeletal disorder associated with pain, swelling, functional limitation, and reduced quality of life. Therapeutic ultrasound and exercise are frequently prescribed conservative interventions; however, evidence regarding their combined effectiveness remains unclear. Objective To systematically evaluate the combined effects of therapeutic ultrasound and any form of exercise on pain and swelling in individuals with knee osteoarthritis. Methods A systematic search of Web of Science, CINAHL, PubMed, AMED, and MEDLINE was conducted for studies published between 2004 and 2024. Randomized controlled trials involving adults aged ≥40 years with knee osteoarthritis were included. Methodological quality was assessed using the Joanna Briggs Institute (JBI) critical appraisal tools. The review was conducted in accordance with PRISMA 2020 guidelines and registered with PROSPERO (CRD42024579383). Results Six studies met the inclusion criteria. Overall, 75% of included studies were rated as moderate to high methodological quality. Evidence consistently supported improvements in pain and functional performance following combined therapeutic ultrasound and exercise interventions. Evidence for reduction in joint swelling was limited, with only one study reporting a significant effect. Conclusion Combined therapeutic ultrasound and exercise interventions appear effective for reducing pain and improving function in individuals with knee osteoarthritis. Evidence supporting effects on swelling is limited. High-quality randomized trials with longer follow-up are required to confirm long-term benefits.