Joint mobilization combined with cervical resistance training for pediatric atlantoaxial rotatory subluxation: Protocol for a randomized controlled trial with musculoskeletal ultrasound assessment

Background Atlantoaxial rotatory subluxation (AARS) is a common cause of acquired painful torticollis in children. Conservative treatment is widely used, but high-quality randomized evidence for structured muscle-focused rehabilitation is limited. Musculoskeletal ultrasound, especially shear-wave elastography (SWE), can measure cervical muscle stiffness in a non-invasive way. This trial aims to test the efficacy and safety of joint mobilization combined with cervical resistance training in children with AARS. It will also examine whether ultrasound-based measures can detect treatment-related changes in cervical muscle stiffness. Methods This is a single-center, assessor- and analyst-blinded, randomized controlled superiority trial with two parallel groups. Seventy children aged 2–18 years with clinically and radiologically confirmed AARS will be randomly assigned in a 1:1 ratio to joint mobilization plus cervical resistance training or joint mobilization alone. Both groups will receive treatment 3 times per week for 4 weeks. The primary outcome is affected-side sternocleidomastoid stiffness at week 4 measured by SWE and adjusted for baseline stiffness. Secondary outcomes include bilateral sternocleidomastoid and upper trapezius SWE parameters, pain intensity, cervical disability, cervical rotation range of motion, overall clinical efficacy, and recurrence-related outcomes. SWE outcomes will be assessed at baseline, week 2, and week 4. Pain and disability outcomes will be assessed at baseline, week 2, week 4, and at 3 and 6 months after treatment. Cervical rotation range of motion will be assessed at baseline, week 2, and week 4. Recurrence-related outcomes will be recorded at the 3- and 6-month follow-up visits. Discussion This randomized controlled trial is designed to provide high-quality evidence regarding the effectiveness of joint mobilization combined with cervical resistance training for pediatric AARS. By incorporating musculoskeletal ultrasound as an objective assessment tool, the study aims to elucidate the relationship between cervical muscle mechanical properties and clinical outcomes. The findings may contribute to the development of standardized, muscle-focused conservative treatment strategies for children with AARS. Trial registration International Traditional Medicine Clinical Trial Registry ( ITMCTR2025002448 ), registered on 27 October 2025.