Elastographic Changes in Cervical Muscle Following Combined Radial Extracorporeal Shockwave Therapy and Orthopedic Manual Therapy: A Randomized Controlled Trial

Background: Non-specific neck pain is associated with altered muscle mechanical properties, including increased stiffness. Radial extracorporeal shockwave therapy (rESWT) and orthopedic manual therapy (OMT) are commonly used interventions, although their combined effects on cervical muscle stiffness remain unclear. This study aimed to evaluate the short-term and within-session effects of adding rESWT to OMT on cervical muscle stiffness measured by means of shear wave elastography (SWE) in individuals with non-specific neck pain. Methods: A randomized controlled trial was conducted including 24 participants (mean age 34.36 years) allocated to an intervention group (IG, n = 12) or a control group (CG, n = 12). The IG received a combined protocol of rESWT (1500 impulses per point at 10 Hz, 2–4 bar) and OMT based on the Maitland concept, while the CG received OMT alone. Primary outcomes included cervical muscle stiffness assessed via SWE expressed in meters per second (m/s) and kilopascals (kPa). Secondary outcomes were pain intensity (VAS), pressure pain threshold (PPT), cervical range of motion (ROM), and shoulder elevation strength (SES). Treatment effects were estimated using ANCOVA adjusted for baseline values. Results: The combined intervention was associated with greater reductions in cervical muscle stiffness compared with the control group, with significant decreases in SWE values (m/s: β = −1.27, p < 0.001; kPa: β = −27.97, p < 0.001). Pain intensity was also reduced (β = −2.12, p = 0.012), while PPT increased (β = 18.84, p = 0.024). Improvements were observed in cervical extension ROM (β = 10.30, p = 0.014) and right SES (β = 3.85, p = 0.044). No significant differences were found for other ROM variables or left SES. Conclusions: The addition of rESWT to OMT was associated with greater short-term improvements in cervical muscle stiffness, pain intensity, and mechanical sensitivity compared with OMT alone in individuals with non-specific neck pain. However, these findings should be interpreted with caution due to the study limitations.