Feasibility and Preliminary Effects of Adding Percutaneous Electrical Nerve Stimulation to a Pain Education and Exercise Program in Patients with Knee Osteoarthritis: A Pilot Randomized Controlled Trial

Objectives: To estimate the preliminary effects of adding percutaneous electrical nerve stimulation (PENS) to a pain education and exercise program on pain sensitization, function, and psychological factors in patients with knee osteoarthritis (KOA), compared with adding a control transcutaneous electrical nerve stimulation (TENS) intervention or sham PENS. Feasibility, safety, and the success of participant blinding were also evaluated. Methods: Thirty patients with KOA were randomly assigned to one of three intervention groups: PENS, control TENS, or sham PENS. All interventions were delivered in addition to a program comprising four pain education sessions and a structured 12-week exercise plan. Primary outcomes included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Visual Analogue Scale (VAS), Chronic Pain Grading Scale (CPGS), Pressure Pain Threshold (PPT), Conditioned Pain Modulation (CPM), and Temporal Summation of Pain (TSP). Psychological variables were assessed as secondary outcomes. Feasibility outcomes included recruitment and retention rates, adherence, adverse events, and blinding success. Results: Significant and consistent improvements over time were observed across the full sample for VAS (Chi2 = 13.38; p = 0.004), CPGS (Chi2 = 15.22; p = 0.002), WOMAC (Chi2 = 31.44; p < 0.001), CPM (Chi2 = 8.77; p = 0.032) and TSP (Chi2 = 53.11; p < 0.001) with changes in potential clinical relevance at the within-group level. However, no statistically significant group–time interactions were found for any variable, suggesting no clear differential effects between interventions. Feasibility outcomes were favorable, with high retention and adherence, a low incidence of mild adverse events, and generally adequate participant blinding. Conclusions: Within the limits of this small exploratory trial, adding PENS to a pain education and exercise program did not appear to provide additional benefits in pain sensitization, function, or psychological factors beyond those achieved with the multimodal program and sham or control electrical stimulation. Feasibility, safety, and blinding outcomes support the viability of conducting a larger definitive trial.