Effects of extracorporeal shockwave therapy for mild knee osteoarthritis: A pilot study

Background: Extracorporeal shockwave therapy (ESWT) has been widely used for various musculoskeletal disorders, including knee osteoarthritis (OA), and has been shown in several studies to be a safe treatment. Although some studies have confirmed the pain-relieving effect of ESWT for knee OA, research on objectivity for structural changes in knee OA is lacking. The aim of this study was to evaluate the ESWT treatment mechanisms in patients with knee OA by means of clinical symptoms and ultrasound techniques as objective measures.Methods: Eighteen patients with mild knee OA were enrolled and randomized to 1 of 2 treatment groups: active or sham. Patients in the experimental group received 0.05 mJ/mm(2) total energy with 1000 pulses weekly for 3 weeks. We then assessed them before, immediately after, and 1-month after the last treatment using the following measurements: pain on a visual analog scale, Western Ontario and McMaster Universities Osteoarthritis Index, Lequesne index, knee joint range of motion, and ultrasonographic features (articular cartilage thickness, Doppler activity, and joint effusion height).Results: All 18 patients completed the 3 treatment sessions without any complication. Both the experimental and control groups improved in terms of OA symptoms, as measured by the visual analog scale, Western Ontario and McMaster Universities Osteoarthritis Index score, and Lequesne index (P < .05). The height of the suprapatellar effusion decreased with time course in the experimental group (P < .05) and showed significant differences with control group at 1-month follow-up (P < .05). The experimental group showed an increase in knee flexion range of motion and Doppler activity immediately following the last treatment session (P < .05), but the effect was not sustained at the 1-month follow-up.Conclusions: Although the therapeutic activity itself could improve OA symptoms, objective improvements were only observed after ESWT. Suprapatellar effusion height was reduced after ESWT and the effect was maintained after 1-month. Our results suggest that ESWT may be effective in reducing suprapatellar effusion and improving symptoms in mild knee OA. However, studies with a larger sample size are required.