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Research Article
Junjie Tong1,2, Jun Yu3, Zhiyang Zhao4, Junli Chang1,2, Peng Zhao1,2, Suxia Guo1,2, Chujie Zhou1,2, Binhan Yan1,2, Fulai Zhao1,2, Xinyu Zhang1,2, Xingyuan Sun1,2, Yanping Yang1,2
1Longhua Hospital,Shanghai University of Traditional Chinese Medicine, 2Key Laboratory of Theory and Therapy of Muscles and Bones,Ministry of Education, 3Rehabilitation Treatment Center,Wuxi Ninth People's Hospital Affiliated to Soochow University, 4ASPINE Health Group
Erratum Notice
Important: There has been an erratum issued for this article. View Erratum Notice
Retraction Notice
The article Assisted Selection of Biomarkers by Linear Discriminant Analysis Effect Size (LEfSe) in Microbiome Data (10.3791/61715) has been retracted by the journal upon the authors' request due to a conflict regarding the data and methodology. View Retraction Notice
This protocol reports a randomized clinical trial that uses the major-curve Cobb angle as the primary structural outcome to evaluate the efficacy of multidimensional traction combined with bracing and mirror-corrective exercises in moderate adolescent idiopathic scoliosis.
This protocol aims to determine whether a patient-specific, multidimensional traction (MDT regimen), delivered alongside standard bracing and mirror-corrective exercises, can improve structural correction in moderate adolescent idiopathic scoliosis (AIS). The study is a pilot randomized clinical trial (RCT) enrolling skeletally immature adolescents (Cobb 20 - 45°) and allocating them 1:1 to (i) brace plus mirror-corrective exercises or (ii) the same program augmented by MDT. Traction vectors are individualized to the curve pattern and flexibility. Interventions are provided over a 3-month period. The MDT arm receives supervised sessions 2x a week, and all participants complete standardized daily exercises and wear braces according to guideline-based prescriptions. The primary outcome is the change in the major-curve Cobb angle from baseline to post-treatment, measured on standardized standing radiographs using consistent end vertebrae and blinded dual reading. Safety, adherence, and adverse events are monitored throughout. In results, adding MDT to bracing and exercises yielded a greater reduction in the major-curve Cobb angle. This protocol operationalizes a reproducible, clinic-ready workflow for parameterized multi-vector traction as an adjunct to conventional nonoperative care, offering a framework to maximize immediate in-brace correction and promote follow-up curve regression. This trial provides methodology and preliminary evidence to support larger, longer follow-up studies through skeletal maturity.
AIS is a three-dimensional structural deformity of the spine with unknown etiology, characterized by axial rotation, coronal curvature, and sagittal imbalance (typically thoracic hypokyphosis or lumbar hyperlordosis)1 . AIS primarily occurs in skeletally immature children and adolescents who are otherwise healthy, most commonly during the adolescent growth spurt. In severe cases, it can lead to chronic back pain, limitation of cardiopulmonary function, and substantial psychological burden, thereby impairing growth, development, and quality of life2.
Currently, the diagnosis of scoliosis relies primarily on standing spine radiographs; the core criterion is the Cobb angle, measured as the angle between the endplate lines of the superior and inferior end vertebrae of the curve. A Cobb angle ≥ 10° defines scoliosis; curves of approximately 20° - 45° are classified as moderate AIS according to international grading3. In Chinese adolescents, epidemiologic data estimates suggest that roughly 19.5% of diagnosed cases are moderate, highlighting the clinical relevance of this cohort4. Management of moderate AIS is primarily non-operative, emphasizing prevention from development to severe deformity (and the attendant possibility of surgery) while striving for the greatest feasible three-dimensional correction and preservation of global spinal alignment5.
Brace therapy represents a standard, non-invasive treatment for moderate AIS. However, when evaluated from the perspectives of correction and stabilization, long-term follow-up shows that its primary effect is to prevent curve development, with only a limited proportion of patients achieving significant and sustained angle reduction6,7,8. Furthermore, delayed development may occur after discontinuation9. Therefore, under standardized bracing prescription and adherence, it is essential to integrate novel evidence-based non-operative strategies to strictly control development and maximize immediate/long-term curve improvement8,10.
Traction therapy aims to improve the extensibility of the spine and surrounding soft tissues. Currently, halo-pelvic traction is commonly applied preoperatively in patients with severe scoliosis to reduce spinal deformity, improve pulmonary function, and lower surgical risk11,12. A 2022 systematic review including 24 studies and 694 patients reported that, compared with pre-traction values, mean coronal Cobb angle reduction was 27.66° after traction and 47.43° after surgery, while sagittal Cobb angle reduction was 27.23° after traction and 36.77° after surgery; forced vital capacity (FVC) increased by 8.44%13. In addition, a 2023 systematic review comprising 8 studies and 210 patients with severe scoliosis demonstrated that preoperative halo-pelvic traction significantly reduced both coronal and sagittal Cobb angles and improved FVC and forced expiratory volume in 1 s (FEV1)12.
However, such traction techniques are primarily used as preoperative adjuncts and have not been effectively applied as conservative treatments for patients with moderate scoliosis. Moreover, these approaches generally lack the ability to individualize traction strategies according to patient-specific curve characteristics11. Building upon the above concept, a multidimensional traction paradigm guided by the patient's curve pattern and flexibility is advocated. Instead of applying longitudinal distraction forces along the vertical axis, traction vectors are oriented according to curve morphology, integrating targeted coronal displacement and transverse anti-rotation torque14,15.
MDT is intended for adolescents with mild to moderate AIS (Cobb angle 10°-45°) and a Risser sign < 5, and is applied as an adjunct to brace treatment and scoliosis-specific corrective exercises to maximize curve correction within a nonoperative framework16. The procedure requires dedicated traction equipment and trained therapists, with individualized traction patterns evaluated before each session using mirror-corrective exercises and adjusted as needed. This approach is not suitable for patients with severe pulmonary impairment, prior spinal surgery, or secondary scoliosis, including neuromuscular scoliosis; during traction, patient tolerance must be continuously monitored, and traction force should be reduced or the procedure discontinued immediately if symptoms such as dyspnea or dizziness occur16.
This article presents a pilot study that provides a systematic and standardized description of a multidimensional traction protocol for moderate AIS. Using a small-sample exploratory design, the study aimed to preliminarily assess feasibility, safety, and potential therapeutic effects, thereby informing the design of future large-scale, systematic cohort studies. The protocol covers patient selection and management, preparation of equipment and materials, adjustment of traction device parameters, and the sequence of corrective maneuvers.
A three-tier methodological framework was implemented, comprising randomized allocation, clinician role segregation, and blinded outcome assessment. Randomization was conducted using a sequentially numbered, opaque, sealed envelope (SNOSE) method to balance baseline confounders, including age and skeletal maturity. In addition, strict functional separation between treating physicians and radiographic assessors minimized subjective bias and ensured the integrity of the primary outcome measure, the Cobb angle.
This protocol outlines a clinical trial employing multidimensional traction combined with bracing and mirror-corrective exercises for the correction of moderate scoliosis. The study protocol was approved by the Ethics Committee of Human Research at the Ninth People's Hospital of Wuxi, affiliated with Soochow University (approval number KS2025036). Before the trial commenced, written informed consent was secured from each participant. From February to May 2025, the Department of Rehabilitation at the Ninth People's Hospital of Wuxi recruited 24 adolescents with AIS who met the inclusion criteria.
1. Experimental setup
2. Recruitment of patients
3. Radiographic assessment
4. Exercise procedure
5. Traction procedure
6. Statistical analysis
A total of 12 patients in the control group and 12 patients in the treatment group were included in the final statistical analysis. The patient demographic is provided in Table 2.
In the treatment group, one participant reported mild lower-back soreness following traction therapy, had no further soreness, and no impact on daily activities or follow-up adherence after physician-guided adjustment of movement patterns. No significant adverse events occurred in the control group, and no participants in either group withdrew due to adverse effects.
The Cobb angle of the major curve in the treatment group (18.42° ± 3.4°) was significantly lower than that in the control group (27.92° ± 3.06°; p < 0.001; Table 3). This pilot study demonstrated that, over the intervention period, MDT combined with bracing and scoliosis-specific corrective exercises produced a measurable corrective effect in patients with moderate adolescent idiopathic scoliosis, with outcomes superior to those achieved with bracing and corrective exercises alone.
Representative Cases
Patient 1 (12 years old) was assigned to the control group and received brace treatment combined with mirror-image correction therapy, whereas patient 2 (also 12 years old) was assigned to the treatment group and received brace treatment, mirror-image correction therapy, and MDT. At baseline, the Cobb angle of the major curve was 25.16° in patient 1 and 31.25° in patient 2 (Table 4, Figure 5). Following the intervention, patient 1 (control group) showed a slight reduction in the Cobb angle to 24.95° (Figure 6A), while patient 2 (treatment group) demonstrated substantial improvement, with a Cobb angle reduced to 14.83° (Figure 6B). These findings indicate that MDT combined with brace and mirror-image correction therapy can effectively improve spinal curvature in patients with moderate AIS.

Figure 1: Thoracic mirror-correction exercise. (A) Illustration of X/Y/Z axes in anatomical orientation (B) Left translation of the thorax in the coronal plane. (C) Right translation of the thorax in the coronal plane. (D) Left side-bending of the thorax in the coronal plane. (F) Left rotation of the thorax in the transverse plane. (G) Right rotation of the thorax in the transverse plane. Please click here to view a larger version of this figure.

Figure 2: Lumbar mirror-correction exercise demonstration. (A) Left translation of the lumbar spine in the coronal plane; (B) right translation of the lumbar spine in the coronal plane; (C) left side-bending of the lumbar spine in the coronal plane; (D) right side-bending of the lumbar spine in the coronal plane; (E) left rotation of the lumbar spine in the transverse plane; (F) right rotation of the lumbar spine in the transverse plane. Please click here to view a larger version of this figure.

Figure 3: Equipment for traction. (A) Traction frame. (B) Foam roller. (C) Fixation strap. (D) Pull strap. Please click here to view a larger version of this figure.

Figure 4: Thoracolumbar scoliosis traction demonstration. (A) Traction device setup; (B) Patient traction-mode introduction. Please click here to view a larger version of this figure.

Figure 5: Baseline standing radiographs of representative patients. (A) Patient 1 in the control group. (B) Patient 2 in the treatment group. Please click here to view a larger version of this figure.

Figure 6: Post-intervention standing radiographs of representative patients. (A) Patient 1 (control group) underwent brace therapy and mirror-corrective exercises without traction. (B) Patient 2 (treatment group) underwent brace therapy, mirror-corrective exercises, and multidimensional traction. Please click here to view a larger version of this figure.
Table 1: Abbreviations of mirror-corrective exercises and their corresponding movements. Please click here to download this Table.
Table 2: Basic information of all patients included. Please click here to download this Table.
Table 3: Scores collected between the treatment and control group. The Cobb angle curve was compared between the two groups. For significance calculation, the t-test was used, and the data were expressed as the mean ± SEM. Compared with the control group, ** p < 0.01, *** p < 0.001. Please click here to download this Table.
Table 4: Scores collected for the representative cases. The Cobb angle curve for the two representative cases. Please click here to download this Table.
In this randomized controlled trial, 24 adolescents (male and female, all fulfilling the inclusion criteria) were randomly assigned in a 1:1 ratio to two groups: (1) brace combined with corrective exercise; (2) brace combined with corrective exercise plus individualized multidimensional traction. The primary outcome was the change in Cobb angle (from baseline to endpoint), measured under standardized radiographic conditions and evaluated by blinded assessors. Results showed that, on the basis of bracing to suppress development, the addition of multidimensional traction produced a more pronounced curve regression trend compared with the control group, suggesting a potential adjunctive corrective effect of traction.
One of the most critical, success-determining steps of this technique is the identification of an optimal mirror-corrective posture, achieved through a combined application of translational and rotational corrective movements. This process requires an integrated interpretation of the patient's radiographic curve pattern, active communication with the patient, and direct visual assessment of the exposed posterior spinal contour in a natural seated position. By comparing the spinal alignment before correction and during the mirror-corrective posture, the therapist evaluates whether the curve appears more linear and balanced in the coronal plane. For operators newly adopting this technique, radiographic verification of the mirror-corrective posture is recommended to confirm corrective accuracy. In this protocol, a mirror-corrective posture achieving a Cobb angle reduction of at least 50% on radiographic assessment is considered appropriate for subsequent traction application. In addition, caregiver education is an essential component of successful implementation, as understanding the corrective principles enables parents to supervise home-based exercises and helps ensure consistent execution of the prescribed movements, thereby supporting optimal therapeutic outcomes.
The mirror-corrective posture also has inherent limitations. It is most effective in patients with a single structural curve; however, in individuals with multi-segment scoliosis, such as those with concurrent thoracic and lumbar curves, the complexity of corrective movement sequencing increases substantially. In these cases, successful implementation requires considerable clinical experience from the therapist and a high level of patient motor control and training accuracy, which may not always be achievable in routine practice. Consequently, corrective movements often need to be trained separately, with distinct mirror-corrective postures prescribed for the thoracic and lumbar regions rather than a single combined pattern. Further prospective cohort studies in patients with multi-segment scoliosis are therefore warranted to evaluate the comparative effectiveness of region-specific training versus combined corrective strategies.
During traction, the most critical procedural consideration is the control of traction intensity. In the current protocol, traction force is not determined by a precise quantitative calculation but is guided by a patient-reported subjective tension scale. A perceived tension level of approximately 8-9, following the initial treatment session, is considered to represent an optimal traction state. This approach requires continuous therapist supervision, with intermittent patient feedback used to increase or decrease the traction force via the adjustment wheel as needed. Although this subjective method allows individualized and tolerable force application, it also represents a methodological limitation. Future device refinements incorporating objective traction force monitoring may enable more precise force quantification, improve documentation of patient responses, and further optimize therapeutic outcomes.
This study also has limitations at the methodological and follow-up levels. Given the association between AIS and skeletal maturity, efficacy assessment should span the period until skeletal maturity. Due to limitations in manpower and resources, the follow-up did not extend to the end of growth, limiting the ability to fully capture long-term outcomes at the skeletal maturity endpoint19. Future studies should, in accordance with CONSORT principles, enlarge the sample size and extend follow-up to obtain more robust effect estimates.
Nevertheless, this study proposed and preliminarily validated a feasible optimization pathway in a real-world outpatient setting: based on the consensus that braces primarily suppress development with limited corrective capacity, and conventional corrective exercises often fail to reach an effective physiological activity threshold, parameterized multi-vector traction tailored to individual curve type and flexibility was implemented in parallel with bracing and corrective exercises. This approach shows promise in longitudinal curve reduction, offering a reproducible framework for evidence-based nonsurgical management of moderate AIS. Future investigations should also explore whether this technique can be adapted for selected patients with severe scoliosis through staged, cycle-based applications aimed at achieving gradual curve reduction, potentially reducing the need for invasive surgical interventions. These hypotheses warrant confirmation through well-designed multicenter prospective cohort studies and randomized trials.
The authors report no conflicts of interest.
This work was supported by grants from the National Nature Science Foundation (82174408, 82374477, and 82474535).
| Digital Radiography (DR) System | Philips Medical (Suzhou) Co., Ltd. | DigitalDiagnostC50 | Imaging Examination |
| Fixation strap | Aspine | Traction Device | Traction Device is used for the correction of scoliosis and restoration of physiological spinal curvatures. |
| Foam roller | Aspine | Foam roller | Traction Device is used for the correction of scoliosis and restoration of physiological spinal curvatures. |
| Pull strap | Aspine | Traction Device | Traction Device is used for the correction of scoliosis and restoration of physiological spinal curvatures. |
| Traction Device | Aspine | Traction Device | Traction Device is used for the correction of scoliosis and restoration of physiological spinal curvatures. |