Phenotype-guided myofascial treatment package versus a fixed massage-based manual therapy comparator for pain sensitivity and muscle stiffness in non-specific neck pain: a randomized controlled trial

To compare a phenotype-guided myofascial treatment package with a fixed massage-based manual therapy comparator, both delivered with the same exercise program, in adults with non-specific neck pain. Methods: This single-center, participant-blinded randomized trial, with outcome-assessor blinding for all measures except SWE, allocated 60 adults 1:1 to a phenotype-guided myofascial treatment package or a fixed massage-based manual therapy comparator. Both groups completed the same therapeutic exercise program and received six sessions over 3 weeks. SWE was acquired by the principal investigator, who had also performed the baseline clinical-elastographic assessment used for treatment-profile assignment. The experimental package combined clinician-assigned treatment profiles with profile-specific manual-therapy protocols. The trial was designed to evaluate the package as delivered and not to validate the phenotype classification system or isolate the effect of phenotype–treatment matching. The protocol prespecified pressure pain threshold (PPT) and shear-wave elastography (SWE) stiffness as two principal objective outcomes. Outcomes were assessed at baseline, post-treatment, and 2-week follow-up. Baseline-adjusted generalized estimating equation models estimated group differences, with Holm correction applied across the four planned PPT and SWE contrasts at post-treatment and follow-up. Results: All 60 participants completed follow-up. At post-treatment, stiffness favored the phenotype-guided treatment package by 0.87 kPa (95% CI, 0.74–1.01; P < 0.001), whereas pressure pain threshold did not differ (-0.03 N/cm²; 95% CI, -0.90 to 0.83; P = 0.938). At follow-up, differences favored the phenotype-guided treatment package for pressure pain threshold (5.06 N/cm²; 95% CI, 4.19–5.93; g = 0.75), stiffness (2.29 kPa; 95% CI, 2.12–2.45; g = 0.97), pain (1.29 points; 95% CI, 0.83–1.75), and disability (2.16 points; 95% CI, 1.68–2.65; all P < 0.001). Conclusions: The phenotype-guided treatment package reduced stiffness and showed better short-term maintenance of pressure pain threshold, pain, and disability at the 2-week post-treatment follow-up. These findings apply to the complete intervention package and do not establish the reliability, validity, or predictive utility of the phenotype classification system. The study does not establish whether these differences persist beyond 2 weeks after treatment cessation. Longer multicenter trials incorporating independent classification validation, extended follow-up, and designs that isolate phenotype–treatment matching are needed. Clinical registration : Registration: Prospectively registered in the ISRCTN registry (ISRCTN14934633) on 22 May 2026, before first participant enrolment on 29 May 2026.