Spinal Rotation in Scoliosis: Why Dr. Justin Dick Measures the Third Dimension Before Calling a Curve Better or Worse

By Dr. Justin Dick, DC · Clear Life Scoliosis and Chiropractic Center, Charlotte, NC · Published October 14, 2026

Scoliosis is usually described by one number, the Cobb angle, which measures sideways bend on a front-to-back X-ray. The deformity is three-dimensional. The vertebrae in a structural curve also rotate around the long axis of the spine, and that rotation produces the rib hump, the uneven waist, and much of what patients see in the mirror.

I am Dr. Justin Dick, and at Clear Life Scoliosis and Chiropractic Center in Charlotte, NC, rotation is part of every scoliosis assessment. This post covers how rotation is measured, what the evidence says about its predictive value, and where the evidence is weaker than some providers claim.

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Why Rotation Is Part of the Definition

The 2016 SOSORT guidelines define scoliosis as a lateral curve of at least 10° with axial rotation. A sideways bend without rotation is a different problem, often functional, which I cover in my post on postural versus structural curves. In a thoracic curve the ribs attach to the rotating vertebrae, so the rib cage turns with them. On the convex side the ribs push backward. That is the rib prominence, discussed in my post on rib prominence and scoliosis.

How Rotation Is Measured

Clinically: angle of trunk rotation

A scoliometer laid across the back during forward bending gives the angle of trunk rotation, or ATR. Bunnell's 1984 study of 1,065 patients established 5° ATR as a criterion for identifying curves of 20° or more. ATR measures the surface, meaning ribs and soft tissue, not the vertebrae directly. It is quick, radiation-free, and useful for tracking, but it is a proxy.

Radiographically: axial vertebral rotation

On a standard PA film, rotation is estimated from where the pedicles sit relative to the vertebral body. These methods are workable but noisy. Logithasan and colleagues noted that manual axial vertebral rotation measurements are time-consuming and carry high inter-rater and intra-rater error. Their automated algorithm agreed with an experienced rater within ±5° on 81 percent of vertebrae, with a mean absolute difference of 4.3°. Any single radiographic rotation number should be read with that margin in mind.

3D reconstruction

Biplanar systems with 3D reconstruction measure rotation more directly. They are the research standard for rotation, but availability is limited and they are not required to manage most patients well.

What Rotation Predicts, and What It Does Not

This is where I see the most overstatement. Here is what the evidence I reviewed supports.

In untreated curves, rotation has not been a strong independent predictor. Lonstein and Carlson followed 727 growing patients with curves of 5° to 29°. Progression related to curve pattern and magnitude, age, Risser sign, and menarchal status. They found no correlation between progression and rotational prominence. That is a 1984 cohort using clinical rather than 3D measures, so it does not close the question, but it is the large natural-history study and it does not support rotation as a standalone predictor.

In braced curves, the change in rotation may matter. Fields and colleagues studied 75 patients in Rigo-Chêneau braces using 3D reconstructions. In-brace rotation by itself did not predict failure once initial curve size was accounted for. Patients whose rotation improved in the brace had an 85 percent lower risk of treatment failure, with a hazard ratio of 0.15. The confidence interval ran from 0.02 to 1.13 and the p value was 0.066, so by the usual threshold that result is not statistically significant, even though the paper's title presents it as a finding. I treat it as a signal worth following, not an established rule.

Coronal correction does not guarantee rotational correction. Wong and colleagues followed eight patients after vertebral body tethering surgery. Coronal Cobb angles improved, while apical axial rotation, after initially improving, worsened by two years. A family looking only at the Cobb angle would have missed that.

Why This Matters for Treatment Decisions

Every conservative approach claims to work in three dimensions. The claim should be checked against measurement. At our Charlotte office I track ATR on every scoliosis visit and read rotation on comparison films, with the measurement error above in mind. When I report a result to a family, I report the Cobb angle, the ATR, and what changed in the sagittal plane. A Cobb reduction with no change in rotation is a different result from one where rotation improved too, and families deserve to know which one they have.

The CLEAR protocol and 3D-designed bracing such as ScoliBrace are built around this three-dimensional model. Whether a given patient's rotation actually improves is something we measure, not assume.

Comparison

Research and Evidence

The rotation literature is mixed in quality. Lonstein and Carlson is a large but older cohort. Fields 2024 is a retrospective single-institution study of 75 patients whose key rotation result did not reach conventional significance. Wong 2024 is an eight-patient surgical series. Logithasan 2022 is a methods paper on 17 radiographs. None of this supports confident claims that a treatment derotates the spine in a predictable way.

In my own work, the Lenke 5C case report, A Non-surgical Multimodal Approach to Adolescent Idiopathic Scoliosis (Lenke 5C) Using an Intensive Two-Week CLEAR Institute Protocol: A Report of Two Cases (Cureus, 2026, PMID 41640942), tracked angle of trunk rotation alongside Cobb angle, chest expansion, and balance testing in two patients. That is case-level evidence. The cervical mechanics study, A Retrospective Cross-Sectional Analysis of Abnormal Cervical Mechanics in Patients With Scoliosis (Cureus, 2025, PMID 41018459), addresses a different plane of the same problem: how often scoliosis travels with sagittal cervical changes that a coronal-only assessment ignores.

References

1. Negrini S, Donzelli S, Aulisa AG, et al. 2016 SOSORT guidelines: orthopaedic and rehabilitation treatment of idiopathic scoliosis during growth. Scoliosis Spinal Disord. 2018;13:3. doi:10.1186/s13013-017-0145-8
2. Bunnell WP. An objective criterion for scoliosis screening. J Bone Joint Surg Am. 1984;66(9):1381-7. PMID 6501335
3. Logithasan V, Wong J, Reformat M, Lou E. Using machine learning to automatically measure axial vertebral rotation on radiographs in adolescents with idiopathic scoliosis. Med Eng Phys. 2022;107:103848. doi:10.1016/j.medengphy.2022.103848
4. Lonstein JE, Carlson JM. The prediction of curve progression in untreated idiopathic scoliosis during growth. J Bone Joint Surg Am. 1984;66(7):1061-71. PMID 6480635
5. Fields MW, Rymond CC, Malka MS, et al. Improvement in axial rotation with bracing reduces the risk of curve progression in patients with adolescent idiopathic scoliosis. Spine Deform. 2024;12(5):1345-1353. doi:10.1007/s43390-024-00888-x
6. Wong TKT, Kwan KYH, Cheung JPY, Cheung KMC. A case series in vertebral body tethering results in improvement in coronal Cobb angle but deterioration in axial rotation: a 3-dimensional analysis. J Spine Surg. 2024;10(4):687-696. doi:10.21037/jss-24-59
7. Whelan J, Paige P, Dick JM. A non-surgical multimodal approach to adolescent idiopathic scoliosis (Lenke 5C) using an intensive two-week CLEAR Institute protocol: a report of two cases. Cureus. 2026;18(1):e102006. doi:10.7759/cureus.102006
8. Dick JM. A retrospective cross-sectional analysis of abnormal cervical mechanics in patients with scoliosis. Cureus. 2025;17(8):e91098. doi:10.7759/cureus.91098

Frequently Asked Questions

Service Area

Clear Life Scoliosis and Chiropractic Center sees patients from Charlotte NC, Huntersville NC, Ballantyne NC, Matthews NC, Concord NC, Mooresville NC, Rock Hill SC, Fort Mill SC. Families from across the Charlotte region and the South Carolina border communities come to the Rachel Freeman Way office for radiographic scoliosis evaluation with Dr. Justin Dick.

Related Pages

• Scoliosis Curve Patterns
• Cobb Angle Explained
• Scoliosis Imaging and Measurement
• Rib Prominence and Scoliosis
• ScoliBrace in Charlotte
• CLEAR Scoliosis Protocol
• Bracing for Scoliosis
• Scoliosis Progression and Compensation
• Research and Evidence
• Dr. Justin Dick Research

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If your child's reports only list a Cobb angle, you are seeing one plane of a three-plane problem. Dr. Justin Dick measures all three at our Charlotte office.

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