Topical Jitongzhi for low back myofascial pain syndrome: study protocol for a single- centre, randomised, double-blind, placebo- and active-controlled superiority trial

Abstract Background: Low back myofascial pain syndrome is a clinically important source of persistent low back pain and disability. Existing treatments may provide symptomatic relief, but treatment response is variable and some options are invasive or associated with systemic adverse effects. Evidence for formulation-specific topical traditional medicines remains limited. Methods: This single-centre, three-arm, parallel-group, randomised, double-blind, placebo- and active-controlled superiority trial will enrol 135 adults aged 18-65 years with low back myofascial pain syndrome. Participants will be allocated in a 1:1:1 ratio to topical Jitongzhi, matched placebo, or an active topical comparator, administered for 4 weeks alongside standardised education and exercise guidance. The primary outcome is change in average low back pain intensity on a 100-mm visual analogue scale from baseline to week 4. Secondary clinical outcomes include disability measured with the Oswestry Disability Index, pain and disability through week 12, rescue analgesic use, adherence, blinding credibility, and adverse events. Inflammatory markers, magnetic resonance imaging and infrared thermography are prespecified exploratory outcomes. The primary comparison is Jitongzhi versus placebo and will use analysis of covariance adjusted for baseline pain. Analyses will follow the intention-to-treat principle. Discussion: This trial is primarily designed to evaluate the treatment-specific clinical efficacy and short-term safety of topical Jitongzhi. No robust formulation-specific human evidence currently establishes a biological mechanism for Jitongzhi. The inflammatory, magnetic resonance imaging and thermographic assessments are hypothesis-generating correlates and will not be interpreted as evidence of causality or used as substitutes for patient-reported outcomes. The findings will inform the design of a future multicentre confirmatory trial. Trial registration: International Traditional Medicine Clinical Trial Registry (ITMCTR), registration number ITMCTR2026000179. Prospectively registered on 7 January 2026 before enrolment of the first participant.