Comparison of Single- and Doublex-Coil rPMS Configurations in Physiotherapy: Perception and Field Distribution in Commonly Treated Areas

Background: Repetitive Peripheral Magnetic Stimulation (rPMS) is an established treatment for various musculoskeletal and neurological conditions. Despite its long-term use, rPMS technology in physiotherapy has seen little innovation, with the single-coil configuration remaining standard. Inspired by advances in transcranial stimulation, novel doublecoil setups allowing adjustable angulation are now being introduced in physiotherapy and may offer improved targeting of common treatment areas. Methods: A review of selected 5,390 treatment records identified the four most commonly treated body areas and standard rPMS protocols. Based on this, 28 healthy volunteers assessed perceived intensity, comfort, penetration depth, and field homogeneity of single- and double-coil configurations. These results were compared with COMSOL simulations evaluating magnetic field distribution across various double-coil angles and in comparison to the conventional single-coil setup. Results: Application of single- and double-coil configurations to commonly treated areas - knee, lower back, shoulder, and hip - revealed notable differences in subjective therapy perception. Patients consistently rated the double-coil setup as more homogeneous and comfortable. Perceived intensity and penetration depth varied with coil angle: at 90° (knee), the double-coil was rated ~30% higher, while at 160° (lower back), the singlecoil was perceived as more intense. COMSOL simulations confirmed that smaller coil angles in the double-coil configuration significantly enhance energy delivery, particularly at 4-5 cm depth. Conclusions: These experimental findings suggest that both the conventional single-coil and the novel double-coil configurations hold potential for physiotherapy applications. While the single-coil setup delivers higher intensity in superficial, anatomically flat regions, the angled dual-coil configuration generates a broader, more uniform field in planar areas and enables deeper, more focused stimulation in curved anatomical regions such as large joints.