Immediate clinical and neuromechanical effects of cervical spine manipulation compared to cervical spine mobilization among individuals with chronic neck pain: a randomized mechanistic cross-over trial

Background Spinal manipulation (SM) and spinal mobilization (Smob) are conservative therapies recommended by several clinical guidelines for the treatment of chronic neck pain (CNP). The purpose of this study was to investigate differences between clinical and neuromechanical effects of SM and Smob in patients with CNP. Methods This study was a randomized mechanistic cross-over trial. Eighty-nine individuals with mechanical neck pain participated in two sessions, 72 h apart, where they randomly received either SM or Smob during the first session and the other intervention during the second session. Recruitment took place in Zurich from August 2023 to January 2024, and in Trois-Rivières from March 2024 to June 2024. Cervical range of motion (ROM), pain intensity, grip-strength and pressure pain threshold (PPT) outcomes were assessed before and after each treatment, while muscular activity was recorded during the treatment using surface electromyographic electrodes (EMG). PPT and EMG activity were assessed for three muscles bilaterally: sternocleidomastoid (SCM), upper trapezius (UT) and tibialis anterior. Outcomes following SM and Smob were compared using linear mixed-effects model, Wilcoxon signed-rank test and McNemar test. Results All ROM increased significantly over time after SM and Smob with no difference between interventions. However, pain intensity analyses showed a significant time x intervention interaction indicating a greater improvement following SM (mean decrease: 0.786 NPRS points) compared with Smob (mean decrease: 0.373 NPRS points) ( β = 0.413, 95% CI [0.160; 0.665], p = 0.002). Muscular response was significantly higher after SM compared to Smob for both SCM (0.144 ± 0.121 vs. 0.023 ± 0.013) and UT (0.083 ± 0.100 vs. 0.024 ± 0.025) muscles, on both sides. A higher PPT was observed for SCM and UT after both interventions. No consistent change was observed for grip-strength. Overall, results showing statistical significance did not reach clinical significance. Conclusion Although SM and Smob both led to higher ROM, SM resulted in immediate lower subjective pain intensity and yielded higher muscular responses for participants with CNP. However, given the mechanistic nature of this study and the absence of clinically significant findings, caution is warranted when considering implications for clinical practice. Trial registration This trial was registered with Open Science Framework (OCF) on May 23, 2023. https://doi.org/ https://doi.org/10.17605/OSF.IO/UNBJ5 .