Thoracic Scoliosis: How a Mid-Back Curve Behaves, What It Does to the Ribs and Lungs, and When It Needs More Workup

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

Thoracic scoliosis is a curve with its apex in the thoracic spine, the mid-back segment that carries the ribs. It is the curve location that most affects the rib cage, because the ribs attach to the vertebrae that rotate. That is why thoracic curves are tied to the rib hump, to lung function as curves get larger, and to the highest rates of progression after growth stops.

I am Dr. Justin Dick, and thoracic curves are a large share of the patients I evaluate at Clear Life Scoliosis and Chiropractic Center in Charlotte, NC. This post covers how the pattern is classified, how it behaves over time, and the findings that make me look past the idiopathic label.

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How Thoracic Curves Are Classified

The Lenke classification, published by Lenke and colleagues in 2001, is the standard language for adolescent idiopathic curves. It sorts curves into six types by which regions are structural (proximal thoracic, main thoracic, thoracolumbar or lumbar), adds a lumbar modifier, and adds a sagittal modifier based on thoracic kyphosis from T5 to T12. A Lenke type 1 is a single main thoracic curve. Independent surgeons in the original reliability study reached kappa values of 0.74 for curve type and 0.94 for the sagittal modifier. Our Lenke classification page explains the system.

The sagittal modifier matters more than many families realize. Thoracic scoliosis commonly comes with a flattened upper back, called hypokyphosis. A flat thoracic spine reduces the front-to-back depth of the chest, which is part of how thoracic curves affect lung volume.

Right Versus Left Thoracic Curves

Curve direction matters. A left thoracic curve, meaning one that is convex to the left, is one of the findings associated with an underlying spinal cord abnormality. In Xu and colleagues' 2020 review of 714 adolescents with scoliosis who had whole-spine MRI, 9.5 percent had intramedullary abnormalities, and a left thoracic curve was an independent risk factor along with male sex, a sharp angular curve, abnormal abdominal reflexes, and ankle clonus. Zhang and colleagues found the same left thoracic association in 504 children under 10 with presumed idiopathic scoliosis, where 18.7 percent had a neural axis abnormality on MRI.

Those percentages come from hospital cohorts that may include more complex cases than a community practice sees, so they overstate the rate in an average patient. The pattern is still consistent: a left thoracic curve, especially in a boy or with neurological findings, warrants MRI and a medical referral before any conservative plan starts.

Progression During and After Growth

During growth, progression risk depends on curve size, skeletal maturity, and age, as covered in my post on the best age to treat scoliosis. After growth, thoracic curves stand out. Weinstein and Ponseti followed 133 curves in 102 patients for an average of 40.5 years. Sixty-eight percent progressed after skeletal maturity. Curves under 30° at maturity tended not to progress. Curves of 50° to 75° at maturity progressed the most, particularly thoracic curves. In thoracic curves, the Cobb angle, apical vertebral rotation, and the Mehta angle were the prognostic factors.

That is the strongest argument for keeping a thoracic curve under about 30° to 40° by the end of growth, and for monitoring larger thoracic curves in adulthood.

The Rib Hump and the Lungs

Thoracic rotation produces the posterior rib prominence most people recognize, covered in my post on rib prominence and scoliosis, and in my post on spinal rotation. Lung function falls gradually as thoracic curves grow. The 2022 meta-regression by Kempen and colleagues found roughly a 1 percent drop in predicted lung function for every 2.6° to 4.5° of thoracic curve. In Weinstein's 50-year natural history study, shortness of breath with daily activity was most strongly associated with thoracic curves above 80°.

Symptoms

Most thoracic curves in adolescents are painless, and that is the problem: they are found by appearance, screening, or chance. Visible signs include a shoulder blade that sticks out, uneven shoulders, a rib prominence on bending, and a trunk that shifts to one side. Significant pain in a young patient with a thoracic curve is not typical and is one more reason to look for another cause.

How Dr. Justin Dick Evaluates Thoracic Scoliosis at Clear Life

At our Charlotte office, a thoracic curve evaluation includes a standing PA and lateral radiograph, Cobb angle, apical rotation, thoracic kyphosis, angle of trunk rotation, and chest expansion, with a neurological screen that includes abdominal reflexes. Left thoracic curves and abnormal neurological findings go to MRI and a medical opinion first. For idiopathic curves, the plan depends on growth stage and magnitude: monitoring, scoliosis-specific rehabilitation through the CLEAR protocol, and bracing with ScoliBrace when indicated.

Comparison

Research and Evidence

Evidence tiering: Weinstein and Ponseti is a long-term cohort and the reference natural history study for adult progression, but it is a single-center series from the mid-twentieth century. The MRI studies are retrospective hospital cohorts with likely referral bias. Kempen is a meta-regression of summary data. The Lenke classification is a reliability study, not an outcome study.

My own published work touches thoracic curves in two places. The 13-month follow-up, Reduction of Adolescent Idiopathic Scoliosis: A 13-Month Follow-Up (Cureus, 2025, PMID 40062184), documents a 42.4° curve reduced to 23.8° with improved chest expansion, a single case. The cervical mechanics study, A Retrospective Cross-Sectional Analysis of Abnormal Cervical Mechanics in Patients With Scoliosis (Cureus, 2025, PMID 41018459), found cervical hypolordosis across 37 patients with scoliosis, which matters for thoracic curves because a flat thoracic spine and a flat cervical spine often travel together.

References

1. Lenke LG, Betz RR, Harms J, et al. Adolescent idiopathic scoliosis: a new classification to determine extent of spinal arthrodesis. J Bone Joint Surg Am. 2001;83(8):1169-81. PMID 11507125
2. Xu W, Zhang X, Zhu Y, et al. An analysis of clinical risk factors for adolescent scoliosis caused by spinal cord abnormalities in China: proposal for a selective whole-spine MRI examination scheme. BMC Musculoskelet Disord. 2020;21(1):187. doi:10.1186/s12891-020-3182-z
3. Zhang W, Sha S, Xu L, et al. The prevalence of intraspinal anomalies in infantile and juvenile patients with presumed idiopathic scoliosis: a MRI-based analysis of 504 patients. BMC Musculoskelet Disord. 2016;17:189. doi:10.1186/s12891-016-1026-7
4. Weinstein SL, Ponseti IV. Curve progression in idiopathic scoliosis. J Bone Joint Surg Am. 1983;65(4):447-55. PMID 6833318
5. Kempen DHR, Heemskerk JL, Kaçmaz G, et al. Pulmonary function in children and adolescents with untreated idiopathic scoliosis: a systematic review with meta-regression analysis. Spine J. 2022;22(7):1178-1190. doi:10.1016/j.spinee.2021.12.011
6. Weinstein SL, Dolan LA, Spratt KF, et al. Health and function of patients with untreated idiopathic scoliosis: a 50-year natural history study. JAMA. 2003;289(5):559-67. doi:10.1001/jama.289.5.559
7. Dick JM, Spurgeon S. Reduction of adolescent idiopathic scoliosis: a 13-month follow-up. Cureus. 2025;17(2):e78669. doi:10.7759/cureus.78669
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

• Lenke Classification
• Scoliosis Curve Patterns
• Rib Prominence and Scoliosis
• Spinal Rotation in Scoliosis
• Best Age to Treat Scoliosis
• When Scoliosis Progresses the Most
• Hyperkyphosis Treatment
• CLEAR Scoliosis Protocol
• ScoliBrace in Charlotte
• Dr. Justin Dick Research

Schedule an Evaluation in Charlotte

If you or your child has a thoracic curve, the direction, size, rotation, and neurological findings decide what comes next. Dr. Justin Dick evaluates all four at our Charlotte office.

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